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MT Methods
The following is a list of descriptions for CIPAC’s MT Methods. For moreinformation, visit the CIPAC website.
International Pesticides Analytical Council (CIPAC) Website: MT 1 FREEZING POINT
OUTLINE OF METHOD:The sample is heated to a temperature above its melting point and then allowed to cool in atemperature controlled jacket. The freezing point is taken as that temperature of the materialwhich remains constant to within 0.5 °C for 4 min.
MT 2 MELTING POINT
OUTLINE OF METHOD.
The sample, in a capillary tube, is heated at a controlled rate in a stirred liquid bath, and thetemperature observed at which a meniscus is formed on the sample, and/or completeliquefaction of the sample occurs.
MT 3 SPECIFIC GRAVITY, DENSITY, AND WEIGHT PER MILLILITRE
3.1 Hydrometer method
OUTLINE OF METHODThe sample is brought to the prescribed temperature and transferred to a hydrometer cylinderat approximately the same temperature. The appropriate hydrometer is lowered into thesample and allowed to settle. The hydrometer is read and the temperature of the sample noted.
If required, the cylinder and its contents are placed in a constant temperature bath to avoidexcessive temperature variation during the test.
3.2 Pyknometer method
OUTLINE OF METHOD In this method the weights of equal volumes or the materialand water are compared.
3.2.1 Capillary stoppered pyknometer SCOPEThe method is suitable for the determination of the specific gravity or density of liquids or solids. Itis not suitable for these determinations on highly volatile liquids.
3.3 Density of suspension concentrates
3.3.1 Hydrometer method
OUTLINE OF METHODDirect determination of density by hydrometer, density bottle or liquid displacement methodhas been shown to be unsuccessful because of aeration and viscosity effects. The density at 20°C of a 1 : 1 aqueous dilution can be readily determined using a hydrometer and hence theactual density of the suspension concentrate can be calculated.
3.3.2 Density bottle method
A portion of the sample is weighed into a density bottle and diluted with water containing ananti-foam agent, using vacuum, if necessary to remove occluded air. The volume of sampletaken is then found by making up to capacity with the anti-foam solution and weighing.
MT 5 MATERIAL SOLUBLE IN ACETONE
SCOPE These methods are intended for materials which are freely soluble inacetone.
5.1 Hot solution
OUTLINE OF METHODThe sample is refluxed with acetone, the acetone is evaporated, and the residue is dried andweighed.
5.2 Solution at room temperature
OUTLINE OF METHOD The material is shaken with acetone, the insoluble material isfiltered off, dried and weighed.
MT 6 MATERIAL SOLUBLE IN HEXANE
SCOPE These methods are intended for materials which are freely soluble inhexane.
OUTLINE OF METHODThe sample is refluxed with hexane, the hexane is evaporated and the residue dried andweighed.
MT 7 MATERIAL SOLUBLE IN ETHANOL
SCOPE These methods are intended for materials which are freely soluble inethanol.
7.1 Hot solution
OUTLINE OF METHOD The sample is refluxed with ethanol, the insoluble material isfiltered off, dried and weighed.
7.2 Solution at room temperature
OUTLINE OF METHOD The material is shaken with ethanol, the insoluble material isfiltered off, dried and weighed.
MT 8 MATERIAL INSOLUBLE IN KEROSENE
OUTLINE OF METHODThe sample, dissolved in kerosene, is exposed to daylight at room temperature for 10 days. Itis examined at intervals for any turbidity and sediment.
MT 9 MATERIALS SOLUBLE IN WATER
SCOPEThe method is intended for materials containing up to 1% water-soluble material.
OUTLINE OF METHODThe sample is shaken in water until all the soluble material has dissolved. The insolublematter is filtered off, dried and weighed.
MT 10 MATERIAL INSOLUBLE IN WATER
SCOPEThe method is used for the determination of (i) impurities in water-soluble technicalpesticides or (ii) insoluble materials in water-soluble formulations which could causeblockage of sieves or jets in spray machinery.
10.1 Hot solution of the sample
OUTLINE OF METHODThe sample is dissolved in boiling water; any insoluble matter is filtered off, dried, andweighed.
10.2 Cold solution of the sample
OUTLINE OF METHODThe sample is dissolved in cold water; any insoluble material is filtered off, dried, andweighed.
10.3 Coarse material insoluble in water
OUTLINE OF METHODThe material is shaken with water for a given time, then the mixture is sieved, and any residueon the sieve is dried and weighed.
10.4 Materials insoluble in aqueous solutions of pesticides
OUTLINE OF METHODThe sample is filtered through a sintered glass crucible, the crucible is dried, weighed andhence the insoluble material content is determined.
MT 11 MATERIAL INSOLUBLE IN XYLENE
SCOPEThe method is intended for the determination of insoluble material in aldrin (HHDN) anddieldrin (HEOD).
MT 12 FLASH POINT
INTRODUCTIONFlash points are obtained by measuring the lowest temperature at which the vapour/air mixtureover a substance, usually an organic liquid, will ignite. Several tests are used, which do notnecessarily give the same measure for a given substance. Even with the strictest attention to detailboth with the apparatus and its use, variations between laboratories can amount to several degrees.
The tests are, however, very important because they are used in various ways to control theconditions under which substances, potentially dangerous as fire hazards, are stored, used andtransported. In the U.K. alone there are six different values which, according tocircumstances, categorise a substance and two test methods are required. Before determining aflash point, ensure that the correct method is used. In the U.K., the Abel Method, described inthe Petroleum (Consolidation) Act, 1928, is the legal method, where appropriate, fordetermining flash points. In the USA a flash point of 27 °C (80 °F) by the Tag Open CupMethod is used by the US Interstate Commerce Commission as the minimum value forclassifying liquids as non-flammable. The Tag Closed Tester is used by the NFPA (NationalFire Protection Association, USA) for their insurance code. The result reported should alwaysspecify the method used, e.g. 10 °C (50 °F) Abel Method.
12.1 Abel method
INTRODUCTIONThe Act makes no provision for liquids having a flash point below 19 °C (66 °F), consequently,additional methods are given for liquids flashing between 32 and 49 °C (90 and 120 °F) and forliquids flashing between 0 and 18 °C (65 °F).
12.2 Tag closed tester
SCOPEThis method determines the flash point of all mobile liquids flashing below 79 °C (175 °F)except products classified as Grade No 4 or heavier fuel oil (Note 10).
OUTLINE OF METHODThe sample is placed in the cup of the tester and, with the lid closed, heated at a slow constantrate. A small flame of specified size is directed into the cup at regular intervals. The flashpoint is taken as the lowest temperature at which application of the test flame causes thevapour above the sample to ignite.
12.3 Pensky-Martens closed tester
SCOPEThis method is intended for determining the closed flash point and the fire point of petroleumand other products having a flash point above 49 °C (120 °F), including fuel oils, viscousmaterials, and suspensions of solids.
OUTLINE OF METHODThe sample is heated at a slow constant rate with continual stirring. A small flame is directedinto the cup at regular intervals with simultaneous interruption of the stirring. The flash pointis the lowest temperature at which application of the test flame causes the vapour above thesample to ignite.
MT 14 FREEZING MIXTURES
14.1 At - 5 ± 1 °C
14.2 At - 10 ± 1 °C
MT 15 SUSPENSIBILITY OF WETTABLE POWDERS IN WATER
15.1 CIPAC method
DEFINITIONSuspensibility is defined as the amount of active ingredient suspended after a given time in acolumn of liquid, of stated height, expressed as a percentage of the amount of activeingredient in the original suspension.
OUTLINE OF METHODA suspension of known concentration in Standard Water or distilled water is prepared, placedin a prescribed measuring cylinder at a constant temperature, and allowed to remainundisturbed for the specified time. The top 9/10ths are drawn off and the content of activeingredient in the bottom 1/10th determined, so allowing the content of the top 9/10th to becalculated.
SCOPEThe method is suitable for suspensions containing up to 1% active ingredient but is notnecessarily suitable for suspensions of higher concentrations.
15.2 AID (Aid for International Development Programme) method
INTRODUCTIONThe suspensibility test is carried out on the material as received and/or after acceleratedstorage. When tested as received, the test is carried out with distilled water, but afteraccelerated storage, Standard Water is used.
SCOPEThis method has been successfully used with (i) 75% DDT wettable powders and (ii)malathion wettable powders, at a concentration of 5 g per 100 ml.
MT 16 MATERIAL INSOLUBLE IN DICHLORODIFLUOROMETHANE
OUTLINE OF METHODBased on WHO Method WHO/M/9 in 'Specifications for Pesticides used in Public Health',4th Ed. 1973.
MT 17 LOSS IN WEIGHT
17.1 Weight loss in an oven for 1 hour
OUTLINE OF METHOD The sample is heated in an oven at thespecified temperature for 1 h.
17.2 Weight loss under vacuum at temperatures above room temperature
OUTLINE OF METHODThe sample is heated to constant weight in a vacuum oven at a specified temperature andpressure.
17.3 Weight loss under vacuum at room temperature
OUTLINE OF METHODThe material is stored for a specified time under reduced pressure in the presence ofphosphorus(V) oxide as desiccant. The percentage loss is determined.
17.4 Weight loss at 100 °C for 4 hours
OUTLINE OF METHODThe material is heated at 100 °C for 4 h, and the loss in weight is determined.
MT 18 STANDARD WATERS
INTRODUCTIONInstructions for the preparation of Standard Waters and of waters of any desired hardness aregiven in CIPAC Monograph 1. For the Standard Waters A to G, stock solutions of Ca++ andMg++ are prepared; the working solutions are then made by dilution of these stock solutions.
18.1 Preparation of Standard Waters A to G (MT 18)
18.2 Preparation of salted waters H and J.
18.3 Non-CIPAC Standard Waters
18.3.1 WHO Standard Hard Water
18.3.2 GB Standard Water
18.3.3 AOAC Standard Water
18.3.4 US Navy Hard Water
18.3.5 Synthetic Nile Water
18.3.6 ASTM Hard Water
18.4 Preparation of Standard Waters of required hardness
18.5 Simplified method of preparing stock solutions
MT 19 PHOSPHATE BUFFER SOLUTIONS
MT 20 STABILITY OF DILUTE EMULSION
MT 21 SILICA FOR CHROMATOGRAPHY
21.1 Silica
21 2 Sorbisil® M 60
21.3 Florisil
MT 22 VISCOSITY
22.1 Viscosity of transparent and opaque liquids in CGS units
22.2 Redwood method
This method determines the viscosity of an oil as a time of flow in seconds through a Redwood viscometer; it does not measure viscosity in absolute units.
22.3 Viscosity of mineral oil
This method describes a procedure for the determination of the kinematic viscosity of liquidpetroleum products, either transparent or opaque, by measuring the time for a volume of theliquid to flow under gravity through a calibrated glass capillary viscometer. The method isintended for liquids which exhibit Newtonian flow MT 23 MISCIBILITY WITH HYDROCARBON OIL
OUTLINE OF METHODThe sample is mixed with a suitable oil and is then allowed to stand at 30 °C for 1 h. Thesolution is examined for layering or separation of solid material.
The test is intended to determine whether a pesticide solution is suitable for application afterdilution with oil instead of water.
MT 24 PHOSPHORUS(V) OXIDE
MT 25 SAND FOR GERMINATION TESTS
MT 26 JOHN INNES COMPOST
26.1 Seeding Compost - with fertilizer
26.2 Seeding Compost - without fertilizer
MT 27 MATERIAL INSOLUBLE IN ACETONE
MT 28 DIMEDONE DERIVATIVE
OUTLINE OF METHODThe aldehyde is heated with dimedone, the condensation product filtered off, and re-crystallized from ethanol. The aldehyde is characterized by the melting point of thisderivative.
MT 29 SULPHATED ASH
MT 30 Water
30.1 Karl Fischer method
OUTLINE OF METHODThe sample is dispersed in methanol, and titrated with standard Karl Fischer reagent of knownwater equivalent.
30.2 Dean and Stark method
OUTLINE OF METHODThe water in the sample is determined by forming an azeotropic binary mixture with toluene, orsolvent naphtha, and then distilling.
30.3 Free water - 'Speedy' method
30.4 Water in acetone solutions.
30.5 Karl Fischer method using pyridine-free reagents
MT 31 FREE ACIDITY OR ALKALINITY
SCOPEThe method is suitable for determining free acidity or alkalinity in technical or formulatedpesticides. It does not allow the determination of acids or alkalis which are insoluble in acetone-water mixtures.
OUTLINE OF METHODThe acidity or alkalinity is determined by titration with standard acid or alkali, in the presenceof methyl red. Where this is impracticable, the end point is determined electrometrically.
31.1 Methyl red indicator method
31.2 Electrometric procedure
31.3 Acidity of petroleum products
MT 32 DETERMINATION OF CONDUCTIVITY
MT 33 TAP DENSITY
OUTLINE OF METHODThe powder is put into a glass measuring cylinder of known mass which is then raised andallowed to fall vertically through a distance of 2.5 cm on to a rubber pad. The operation isrepeated 50 times and the final volume of the powder is measured.
MT 34 DUSTABILITY TESTS AFTER TROPICAL STORAGE
MT 35 OIL INSOLUBLE MATERIAL
MT 36 EMULSION CHARACTERISTICS OF EMULSIFIABLE CONCENTRATES
The (existing) methods are not always suitable for emulsifiable concentrates containing solid active ingredients. For these and for products used in very low concentrations alternativemethods are under consideration.
36.1 Five per cent v/v oil phase
36.2 1 per cent v/v oil phase
36.3 Emulsion characteristics and re-emulsification properties
SCOPEThe method is suitable for determining the emulsification stability of emulsion formed by thedispersion of emulsifiable concentrates (EC), or emulsions, oil in water (EW) at dilution ratesof 0.1 % to 5 % (Note 1).
OUTLINE OF METHODAn emulsion of known concentration in standard water is prepared. The stability of thisemulsion is then assessed in terms of amounts of free 'oil' and/or 'cream', which separateswhile the emulsion is allowed to stand undisturbed for 24 h. The ability of the system to re-emulsify at the end of the 24 h period is also determined.
MT 37 ISOLATION OF ACTIVE INGREDIENT
37.1 Extraction with acetone
37.2 Extraction with petroleum spirit
37.3 Removal of solvents by distillation
MT 38 ORGANIC CHLORINE
38.1 Potassium - xylene method
OUTLINE OF METHODThe organic chlorine is converted by potassium in xylene to the chloride ion which is thentitrated by the silver nitrate/ammonium thiocyanate procedure, or determinedelectrometrically.
38.2 Stepanov method
38.3 Oxygen flask method
MT 39 STABILITY OF LIQUID FORMULATIONS AT 0°C
39.1 Emulsifiable concentrates and solutions
OUTLINE OF METHODA sample is maintained at 0°C for 1 h and the volume of any separated solid or oily matter isthen recorded. Storage at 0°C is continued for 7 days, any solid matter is settled bycentrifuging and its volume recorded.
39.2 Aqueous solutions
39.3 Low temperature stability of liquid formulations
MT 40 WATER CONTENT AND SUSPENDED SOLIDS IN TECHNICAL ESTERS
OF PHENOXYALKANOIC ACIDS
OUTLINE OF METHOD The ester is dissolved in toluene. Any insoluble matter isfiltered off, dried and weighed.
MT 41 DILUTION STABILITY OF HERBICIDE AQUEOUS SOLUTIONS
MT 42 PARTICLE SIZE OF COPPER AND SULPHUR PRODUCTS
SCOPEThe method is intended for determining the particle size of water insoluble copper compoundsand 'micronized' sulphur products.
OUTLINE OF METHODThe method is based on the rate of settling of particles in suspension in a liquid of knownviscosity. A suspension of the sample is successively decanted into a series of beakers. Acumulative curve of particle size is constructed.
42.1 Formulations without carriers
OUTLINE OF METHODThe sample is made into a suspension of unit particles. This is then successively decanted intoa series of beakers.
42.2 Formulations containing carriers
OUTLINE OF METHOD.
A suspension is successively decanted as in MT 42.1. Separate determinations of the totalweight (active ingredient plus carrier) and the active ingredient for each successive deposit aremade. These determinations give the particle size of the active ingredient and also that of thecarrier.
MT 43 PARTICLE SIZE DISTRIBUTION OF DDT WETTABLE POWDERS
OUTLINE OF METHOD.
A modified Andreason method is described in which a uniformly dispersed suspension of theDDT in standard water settles under stable conditions. Samples are withdrawn from a fixedpoint in the suspension, after given times, and the DDT content of each is then determined(Note 1).
It is assumed that the suspension is sufficiently dilute to allow settling without mutual particleinterference and, also, that Stokes' Law is obeyed.
MT 44 'FLOW NUMBER'
The method has not been collaboratively tested, although it has been shown to be useful: SCOPEThe method is suitable for the determination of flowability (flowing properties) of powders,i.e. mineral carriers, formulated dusts and wettable powders containing pesticides. Themethod is not suitable for:(i) seed treatment powders or other powders to which oils have been added to suppressdustiness, or(ii) powders which do not form homogeneous mixtures with sand (Note 2). The products to betested should pass a 250 µm test sieve; products of larger particle size are examined for freeflow by visual inspection.
MT 45 REMOVAL OF DYES
OUTLINE OF METHODThe sample, dissolved in petroleum spirit, is chromatographed on a column of alumina,Brockmann activity III.
MT 46 ACCELERATED STORAGE PROCEDURE
SCOPEThe objective is to accelerate the ageing of a product by heating.
No evidence is available to indicate that a product which has failed this test has a satisfactoryshelf life (of at least 2 years) either in the tropics or in temperate zones. The test thus providesa useful guide on performance after storage in hot or temperate climates. However, a productmay pass the test and yet be unsatisfactory in the field.
General method
As this is intended as a model procedure, temperature and times specified are examples only since the parameters will normally be given for individual pesticide formulations. However,
as the factors involved in storage are numerous, several accelerated storage procedures are
described.
46.2 AID methods
46.3 Accelerated storage procedure (combined method)
SCOPEThe objective is to simulate the normal long-term ageing of a formulation by heating.
Although actual data from a product in sales packs and stored in e.g. warehouses is preferable,the accelerated storage test provides useful guidance on performance after storage since manyformulations that perform poorly in the accelerated test do not have satisfactory shelf lives (ofat least 2 years) in hot or temperate climates.
OUTLINE OF METHODA sample is placed in a glass bottle (or another suitable container), which is subsequentlyclosed and placed in an oven at a specified temperature for a defined period of time.
MT 47 PERSISTENT FOAMING
MT 48 STABILITY OF TAR OIL PRODUCTS
48.1 Undiluted miscible type
OUTLINE OF METHODThe product is stored at -10°C for 16 h and is examined for the presence of cloudiness anddeposits. It is then warmed to 0°C and rapidly poured into ice-cold, distilled water. Themixture is allowed to stand at room temperature for 4 h and is examined for the separation ofoil, then poured through a sieve and the sieve examined for any material retained e.g.
crystalline or slimy deposits.
48.2 Stock emulsion type
OUTLINE OF PROCEDUREA sample is cooled to -5°C for 48 h and is then examined for traces of separated oil andsediment. It is then heated to 20°C for 1 h, poured into distilled water at the same temperature,and allowed to stand for 4 h. The amount of oil that has separated is noted. The mixture is thenpoured through a sieve which is examined for any material retained e.g. crystalline or slimydeposit.
MT 49 STABILITY OF TAR AND PETROLEUM PRODUCTS - DILUTED
49.1 Tar oils - miscible and stock emulsion type
OUTLINE OF METHODThe sample is added to GB Standard Water, stirred, allowed to stand for 4 h and, after gentlestirring, poured through a sieve which is then examined for traces of separated oil.
49.2 Petroleum oil - miscible type
MT 50 ALUMINA
MT 51 STABILITY OF UNDILUTED PETROLEUM - TAR AND PETROLEUM OIL
PRODUCTS
51.1 Miscible type
OUTLINE OF METHODA sample is cooled to -5 ± 1°C and is then examined for cloudiness. It is warmed to 0°C, pouredrapidly into ice-cold, distilled water and stirred vigorously. After standing at room temperaturefor 4 h, it is then examined for oil.
MT 52 STABILITY OF DILUTED PETROLEUM - TAR AND PETROLEUM OIL
PRODUCTS
52.1 Miscible type
The product is added to vigorously stirred GB Standard Water and allowed to stand for 4 h. It isthen examined for traces of oil.
MT 53 WETTABILITY
53.1 Wetting time of a standard tape
OUTLINE OF METHODA weighted length of cotton tape is dropped into a tall cylinder containing an aqueoussolution of a wetting agent. The time required for the thread connecting the weight and thetape to relax is recorded as the sinking time. Concentrations of wetters requiring a sinking time of 15 sec are compared. The test may be used on formulated pesticides but it does notnecessarily apply to cationic wetters.
53.2 Wetting of leaf surfaces
A freshly picked leaf is immersed in a solution of wetting agent under standardized conditionsand a visual examination of the area wetted is made.
53.3 Wetting of wettable powders
SCOPEThe method describes a procedure for the determination of the time of complete wetting ofwettable powders.
OUTLINE OF METHODA weighed amount of the powder is dropped on water in a beaker from a specified height. Thetime for complete wetting is determined.
MT 54 STABILITY OF UNDILUTED PETROLEUM OIL FORMULATIONS,
INCLUDING THOSE CONTAINING DNOC AND TAR PRODUCTS
OUTLINE OF METHODThe product is cooled, examined for separation of free oil, heated and then poured intodistilled water. After standing, it is examined for traces of free oil.
MT 55 STABILITY OF AQUEOUS DILUTIONS OF PETROLEUM OIL
FORMULATIONS, INCLUDING THOSE CONTAINING DNOC AND TAR
PRODUCTS
55.1 Petroleum oil and tar products
OUTLINE OF METHODThe sample is added to GB Standard Water, mixed thoroughly, and allowed to stand for 4 h;the amount of free oil is noted.
55.2 Petroleum Oil Formulations, including those containing DNOC.
55.3 Petroleum oils for orchard use.
55.4 Petroleum oils for glasshouse use.
MT 56 VOLATILITY OF NEUTRAL OIL
56.1 Preliminary examination
56.2 Full method.
MT 57 UNSULPHONATED RESIDUE OF NEUTRAL OIL
MT 58 DUST CONTENT AND APPARENT DENSITY OF GRANULAR PESTICIDE
FORMULATIONS
58.1 Sampling
58.2 Preparation of sample.
58.3 Sieve analysis
58.4 Apparent Density after compaction without pressure
MT 59 SIEVE ANALYSIS
OUTLINE OF METHOD
Sieve analysis consists of the quantitative separation of a powder into fractions with different
ranges of particle size by use of an appropriate sieve or sieves.
Sieving is carried out either (i) dry, by a process of shaking, tapping and brushing; or (ii) wet,
by washing the material on the sieve with a stream of water. Treatment of the sample with a
wetting agent is used, where necessary, to assist the sieving process. The specification or the
method of analysis for the material under test gives directions as to whether dry or wet sieving
is to be applied.
Where more than one nominal aperture size is specified, the sample is first sieved on the
smallest aperture sieve. This removes most of the very fine particles which tend to clog the
sieves and may interfere with quantitative separation of the larger particles. The sieves are
stacked in order of aperture size with the largest at the top; the retained material is transferred
to the largest aperture sieve, and sieving continued until passage of undersize material through
each sieve is substantially complete.
The residue on each sieve is finally transferred to a dish, dried if wet sieving has been used,
and weighed.
59.1 Dry sieving - dusts
59.2 Granular products. See MT 58
59.3 Wet sieving
MT 60 SOLUBILITY OF THE ALKALI METAL SALTS OF PHENOXYALKANOIC
ACID HERBICIDES AND THEIR SOLID FORMULATIONS
MT 61 DISTILLATION RANGE OF NEUTRAL OIL
MT 64 HYDROLYSABLE ORGANIC CHLORINE
64.1 HCH technical
64.2 HCH dusts and dispersible powders
64.3 HCH emulsifiable concentrates and solutions
64.4 DDT technical
64.5 DDT dusts and wettable powders
64.6 DDT emulsifiable concentrates and solutions
MT 65 ORGANIC CHLORINE IN PESTICIDES IN AQUEOUS EMULSIONS
OUTLINE OF METHODThe pesticide is absorbed on granulated carbon, which is then extracted with hydrocarbon-alcohol solvent mixture. The extracted material is reacted with sodium and the chloride ionproduced is determined by potentiometric titration with standard silver nitrate solution.
SCOPEThe method is suitable for aqueous emulsions produced from emulsion concentrates of HCH,lindane, DDT, endrin, HEOD, and HHDN. It is probably suitable for other organochlorinepesticides.
MT 66 FREE ACIDITY OF PHENOXYALKANOIC ESTERS
OUTLINE OF METHODThe material is dissolved in ethanol, cooled and the free acid titrated with standard sodiumhydroxide.
MT 67 FAT EXTRACTION APPARATUS
MT 68 TOTAL CHLORIDES
68.1 Chlorides in phenoxyalkanoic acids
OUTLINE OF METHODThe material is dissolved in ethanol, diluted with water, and the chloride determined bytitration with silver nitrate.
68.2 Chlorides in technical mercurial compounds
OUTLINE OF METHODHeat the sample with sodium hydroxide and zinc metal, filter off the liberated mercury as azinc amalgam, and determine the chloride in the filtrate by the Volhard method.
SCOPEThe method is suitable for the determination of the total chloride in technical mercurialchlorides, e.g., mercury(II) chloride, phenylmercury(II) chloride, etc.
MT 69 FREE PHENOLS
69.1 2,4-D
OUTLINE OF METHODThe absorbance of an ethanolic-ammonia solution of the sample is determined, after adding 4-aminophenazone and potassium hexacyanoferrate(III) solutions 69.2 MCPA
69.3 2,4-DB
69.4 Dichlorprop
69.5 MCPB
69.6 Mecoprop
MT 71 SOLUBILITY IN SODIUM HYDROXIDE
71.1 Phenoxyalkanoic acids
71.2 Cresols
71.3 Bromoxynil and Ioxynil
OUTLINE OF METHODThe material is dissolved in sodium hydroxide and the insoluble material is determined bysieving.
MT 73 HARDNESS OF WATER
MT 74 NEUTRALITY
OUTLINE OF METHODThe sample is shaken with distilled water to which an acid-base indicator has been added. Thecolour of the aqueous layer is compared with that of a neutral solution of the indicator.
MT 75 DETERMINATION OF pH VALUES
75.1 General method
OUTLINE OF METHODThe pH value of a liquid is determined by means of a pH meter and a glass electrode.
75.2 pH of aqueous dispersions
75.3 Determination of pH values (revised method)
OUTLINE OF METHODThe pH value of a mixture of a sample with water or of an undiluted aqueous formulation isdetermined by means of a pH meter and an electrode system.
MT 76 SOLUBILITY IN AQUEOUS TRIETHANOLAMINE
MT 77 DETERMINATION OF 1-CHLORO-2,3-EPOXYPROPANE
OUTLINE OF METHODThe 1-chloro-2,3-epoxypropane is reacted with trimethylamine hydrochloride, and theliberated trimethylamine is titrated with perchloric acid.
MT 78 HYDROGEN SULPHIDE AND THIOLS
MT 79 ACID WASH
Equal volumes of the sample and sulphuric acid (95% m/m) are shaken together. The colour ofthe acid is compared with solutions of standard colour MT 80 RESIDUE ON EVAPORATION
80.1 Low boiling products
OUTLINE OF METHODSeventy five per cent of the sample is distilled. The residue in the flask is transferred to aweighed dish, and the evaporation completed on a water bath; the residue remaining oncompletion of the test is determined by weighing.
80.2 Cresols
OUTLINE OF METHODThe weight of residue is determined after evaporation of the sample, first on a boiling waterbath and then in an oven at 105°C.
MT 81 SOLUBLE ALKALINITY
OUTLINE OF METHODThe sample is boiled with water, the mixture is filtered, and the filtrate is titrated with sulphuricacid to a methyl red end point.
MT 82 SOLUBLE CHLORIDES
OUTLINE OF METHODThe solution retained from MT 81 is titrated with silver nitrate, using potassium chromate asindicator.
MT 83 SEED ADHESION TEST FOR POWDERS FOR SEED TREATMENT
83.1 Cereal seeds
OUTLINE OF METHODThe seed is shaken with the powder under standard conditions. The amount of pesticide on theseed is determined.
83.2 Pea seeds
OUTLINE OF METHODThe seed is treated with the specified amount of powder at a specified application rate understandardized conditions similar to those in a simple tumbler seed treatment machine. Theamount of pesticide is then determined.
MT 84 IGNITION TESTS
Assessment of the spontaneous ignition potential of dithiocarbamates
OUTLINE OF METHODHot air is passed over the sample until ignition takes place. The temperature of the air streamon either side of the sample is noted, and also the time taken for ignition to occur. The nature ofburning is noted.
MT 86 KIESELGUHR
86.1 For GLC
OUTLINE OF METHODNeutral kieselguhr is prepared by treatment first with acid and then with alkali. The material isthen dried and sieved to size. 86.2 For Partition Chromatography
MT 87 MATERIALS SOLUBLE IN CHLOROFORM
OUTLINE OF METHODThe sample is extracted with hot chloroform, the chloroform is evaporated and the residue isdried and weighed. Alternatively the sample is shaken with cold chloroform, filtered, and theresidue is dried to constant weight.
SCOPEThe methods are suitable for samples which are freely soluble in chloroform.
87.1 Hot solution
87.2 Cold solution
MT 90 MATERIALS SOLUBLE IN TOLUENE
SCOPEThe method is suitable for samples which are freely soluble in toluene.
OUTLINE OF METHODThe sample is shaken with toluene, the suspension is centrifuged and the residue, after removalof the solution, is dried and weighed.
MT 92 DETERMINATION OF LEAD
92.1 Dithizone general method
After destruction of organic matter and separation from interfering substances, lead is extractedwith a solution of 1,5-diphenyl-3-thiocarbazone (dithizone) at pH 9.0 to 9.5, and determinedabsorptiometrically as the pink complex.
MT 93 DETERMINATION OF MANGANESE
INTRODUCTIONTwo methods for determining manganese are given. The first, the bismuthate method, ispreferred and can be applied to all samples. The second, an EDTA titration, is quicker andsuitable for technical materials. It can give erroneous results for certain formulations due to thepresence of interfering substances.
93.1 Bismuthate Method
OUTLINE OF METHODThe sample is dispersed in nitric acid, the mixture is boiled, and insoluble material is filtered off.
Sodium bismuthate is added, the excess is filtered off, and the filtrate is treated with a measuredexcess of diammonium iron(II) sulphate solution. The residual iron(II) sulphate is titrated withpotassium permanganate.
93.2 EDTA Method
OUTLINE OF METHODThe material is dissolved in a known excess of EDTA solution. The mixture is gently boiled,cooled, and ascorbic acid and ammonia buffer solution are added. The excess EDTA is titratedwith magnesium sulphate using mordant black 11.
MT 94 DETERMINATION OF ZINC
94.1 Zinc dithiocarbamates
OUTLINE OF PROCEDUREThe dithiocarbamate is decomposed with sulphuric acid and nitric acid, disodium disulphite isadded to reduce any iron, and then mercury(II) thiocyanate solution is added. The resultingcomplex is filtered off, dried and weighed.
MT 95 DETERMINATION OF IRON
95.1 Total iron
The iron present is reduced to divalent iron with a silver reductor, and divalent iron is titratedwith cerium(IV) sulphate using ferroin sulphate as indicator.
95.1.2 Reduction of trivalent iron. OUTLINE OF METHODThe divalent iron present is oxidized with an excess of potassium permanganate and the solutionis boiled to destroy the excess. The solution is then titrated with titanium(III) sulphate usingammonium thiocyanate as indicator.
The iron is titrated with EDTA using salicylic acid in acetone as indicator.
95.2 Divalent iron
The divalent iron is titrated with cerium(IV) sulphate solution using ferroin sulphate as indicator.
95.3 Trivalent iron
As for 95.1.2 except that the oxidation of the divalent iron with potassium permanganate isomitted.
MT 97 SEPARATION AND IDENTIFICATION OF HERBICIDES
SCOPEThe method is suitable for the separation and identification of the following herbicides: MCPA,MCPB, 2,4-D, 2,4-DB, 2,4,5-T, DNOC, dinoseb, dalapon either alone or in mixtures of technicaland formulated materials.
MT 98 WATER-SOLUBLE COPPER
98.1 Colorimetric method
OUTLINE OF METHODThe water soluble copper is extracted and reduced to the Cu+ state. Bathocurproine is addedand the absorbance of the coloured copper complex formed is measured at 465 nm.
SCOPEThe method is suitable for the determination of water-soluble copper in copper oxychloride andother water-insoluble copper fungicides.
98.2 Atomic absorption spectrophotometric method
OUTLINE OF METHODThe sample is dispersed in de-ionized water. The mixture is centrifuged, filtered and the copperdetermined by means of an atomic absorption spectrophotometer.
MT 99 DETERMINATION OF ARSENIC
OUTLINE OF METHODThe arsenic is reduced with zinc in hydrochloric acid to yield arsine, which is absorbed in asolution of silver diethyldithiocarbamate in quinoline. The purplish-red colour produced ismeasured by the colloidally dispersed silver photometrically at 540 nm.
MT 100 TOTAL CHLORIDES
100.1 In mercurials
SCOPEThe method is suitable for the determination of chloride in technical mercurial chlorides, e.g.
phenylmercury(II) chloride.
OUTLINE OF METHODThe sample is heated with sodium hydroxide and excess of zinc, the liberated mercury is filteredoff as a zinc amalgam, and the sodium chloride in the filtrate is determined by the Volhardmethod.
MT 101 HEPTANE-INSOLUBLE MATERIALS IN ALDRIN
OUTLINE OF METHODA prescribed amount of sample is dissolved in heptane. Any residue is filtered off, dried andweighed.
MT 104 IDENTIFICATION OF MERCURIAL COMPOUNDS
104.1 Organomercury compounds
OUTLINE OF METHODPortions of the material are dissolved in (i) acetone, and (ii) acetone/aqueous sodium chloride,and spotted onto a silica gel thin layer plate, which is then developed withcyclohexane/acetone mixture. The plate is prayed with copper(II) sulphate and potassiumiodide/sodium sulphite solutions. The spots produced are compared with those produced in asimilar manner from a mixed solution of standard mercury compounds in acetone.
MT 105 PREPARATION OF NITROGEN COMPLEXES OF NITRO COMPOUNDS
105.1 Technical compounds
The nitron complex of the compound is prepared and its melting point is determined by a 105.2 Esters
The ester is converted to the corresponding phenol with butylamine and hydrochloric acid.
The phenol is extracted with petroleum spirit, the solvent is evaporated, and the nitroncomplex is prepared.
MT 107 AMMONIA-AMMONIUM CHLORIDE BUFFER SOLUTION-pH 10
MT 108 DINITRO COMPOUNDS - SOLUBILITY OF SALTS AND MATERIALS
INSOLUBLE IN ALKALI
108.1 Ammonium salt
The technical material is dissolved in methanol, the appropriate base is added and, thesolution is diluted with Standard Water. Any insoluble matter is filtered off and weighed.
108.2 Sodium salt
108.3 Triethanolamine salt.
MT 109 ACID CONTENT OF DINITRO COMPOUNDS
OUTLINE OF METHODThe material is extracted with a known amount of standard hydrochloric acid. The extract istitrated with standard sodium hydroxide solution and the free acidity is calculated.
MT 110 MERCULRIAL IMPURITIES IN TECHNICAL AND FORMULATED
MERCURIALS
INTRODUCTIONThe methods are intended for the determination of mercurial impurities which are pesticidally inactive,phytotoxic, or are present in large amounts in the named compound thus giving a poor qualityproduct.
General TLC method for samples containing more than 1% of inorganic
mercury
SCOPEThe method is suitable for the determination of 1 to 14% inorganic mercury salts in technicaland formulated organomercury(II) compounds.
OUTLINE OF METHODThe sample is dissolved in acetone/aqueous sodium chloride or dioxane/ aqueous sodiumchloride. The solution is spotted on to a silica gel TLC plate, developed with carbontetrachloride/acetone, and sprayed with copper(II) sulphate and potassium iodide/sodiumsulphite solutions. The resulting spots are compared with standard spots from puremercury(II) chloride to give the inorganic mercury content of the sample.
Gravimetric method
SCOPEThe method is suitable for the determination of inorganic mercury, in phenylmercury(II)acetate, chloride and nitrate.
OUTLINE OF METHODInorganic and any organic mercury compounds soluble in acetic acid are extracted from thesample by stirring it with hot acetic acid. The mixture is filtered, the filtrate is neutralizedwith ammonia, and potassium iodide is added to precipitate phenylmercury(II) compound asphenylmercury(II) iodide which is filtered off. The filtrate is heated with bis(ethylenediamine)copper(II) sulphate solution to form an insoluble mercury complex [bis(ethylene-diamine)mercury(II) sulphate] which is then filtered off, and weighed.
Sulphide colorimetric method
2-Ethoxyethylmercury(II) and 2-methoxyethyl(II) chlorides - Determination of
the mercury content of materials insoluble in sodium hydrogen carbonate solution
Mercurial seed treatments containing mercury(II) chloride and/or iodide -
Determination of free mercury and mercury from mercury(I) salts
Phenyl mercury(II) chloride - Determination of water-soluble inorganic and/or
organic mercury compounds
MT 113 SILANIZATION OF GAS CHROMATOGRAPHIC COLUMNS
113.1 Off column
113.2 On column
MT 114 CORRECTIONS FOR INTERFERING PEAKS
INTRODUCTIONThis is a correction for peaks from the active ingredients which interfere with peaks from theinternal standards or vice versa. It is applicable to gas liquid and high performance liquidchromatography methods. It is not applicable where both the active ingredient peak and theinternal standard peak mutually interfere. This should be avoided if at all possible by carefulselection of the internal standard. MT 116 MERCURY(II) SALTS - CHARCTERISTIC REACTIONS
116.1 Precipitation of sulphide
116.2 Deposition of mercury on copper
116.3 Reduction with tin(II) chloride
116.4 Precipitation of mercury(II) iodide
116.5 Precipitation of mercury(II) oxide with sodium hydroxide
116.6 Precipitation of ammonium mercury(II) chloride with ammonia solution
MT 117 TEST FOR CHLORIDE
117.1 Liberation of chlorine
117.2 Precipitation of silver chloride
117.3 Formation of chromyl dichloride (CrOCl2)
MT 118 TESTS FOR IODIDES
118.1 Liberation of iodine
118.2 Precipitation of silver iodide
118.3 Liberation of iodine
118.4 Precipitation of mercury(II) iodide
118.5 Precipitation of copper(I) iodide
MT 120 TESTS FOR PHOSPHATES
MT 121 TESTS FOR SILICATES
121.1 Preparation of sample
121.2 Precipitation of silicic acid and evaluation of ammonia
121.3 Formation of silicic acid gel
121.4 Precipitation of silver silicate
MT 126 EXTRACTABLE ACIDS
OUTLINE OF METHODA solution of the formulation as specified in the appropriate monograph is prepared, andacidified with hydrochloric acid. The precipitated acids are extracted with diethyl ether. Theether is removed by evaporation and the residue is dissolved in neutral ethanol. This solutionof the acids is titrated with sodium hydroxide, using the specified indicator MT 127 MELTING POINT OF EXTRACTABLE ACIDS
OUTLINE OF METHODThe solution is acidified and the liberated acids are extracted with diethyl ether. The ethersolution is dried with anhydrous sodium sulphate and evaporated to dryness. The melting andmixed melting points of the acids are then determined.
MT 129 GAS LIQUID CHROMATOGRAPHY OF PHENOXYALKANOIC AND
OTHER HERBICIDES
SCOPEThe method provides a suitable basis for the determination of the active ingredient(s) in thetechnical material and in most formulations containing the ionic salts of bromoxynil, 2,4-D,2,4-DB, dichlorprop, fenoprop, MCPA, MCPB, mecoprop, 2,4,5-T and 2,3,6-TBA.
OUTLINE OF METHODThe herbicides are precipitated from alkaline solution with hydrochloric acid, extracted withdiethyl ether and converted to their methyl esters or ethers with either diazomethane ormethanol + sulphuric acid. The esters of ethers are separated by gas liquid chromatography ona column of Chromosorb G (AW, DMCS) or Chromosorb W (AW, DMCS) coated withApiezon L, and the active ingredient determined, preferably by flame-ionization detection,using an internal standard. Duplicate sample solutions are prepared by the method given in themonograph for the active ingredient. Two portions of each solution are methylated andduplicate chromatograms are prepared for each, i.e. a total of eight chromatograms from thesample.
For schematic flow sheet of methods of analysis see Fig. 38. For routine purposes only oneportion of each solution need be used, i.e. a total of four chromatograms from the sample.
129.1 Preparation of solutions for methylation
129.2 Methylation of acids
129.3 Gas chromatography
MT 130 COLORIMETRIC TESTS FOR IDENTIFYING CERTAIN ALKYLENE-
BIS(DITHIOCARBAMATES) IN TECHNICAL MATERIAL AND FORMULATED
PRODUCTS
OUTLINE OF METHOD AND PRINCIPLES INVOLVEDAqueous dispersions of the unknown sample and the standard reference dithiocarbamates arespotted systematically on to the filter paper and allowed to dry. Different spots from sampleand standards are treated with (i) acid dithizone (ii) sodium hydroxide and (iii) sodiumhydroxide and acid dithizone. The colours produced due to the metallic moieties present inthe central powder spot and annulus are compared with those from the standards and thisenables the sample to be categorised and sometimes positively identified. Supplementary testsare used to indicate the presence of water soluble or insoluble zinc salts such as sulphate orcarbonate.
Following the step-wise procedure, elimination of the various possible dithiocarbamates fromthe sample is progressively achieved until finally, spots derived from a chloroform dispersionof the sample and mancozeb standard, and to which neutral dithizone is added, distinguishbetween mancozeb, and a mixture of maneb and zinc sulphate or other water soluble zincsalts. These are indistinguishable in aqueous suspension, and the non-aqueous neutralconditions are deliberately chosen to suppress ionization of the zinc salts or zinc oxide.
Mancozeb therefore gives a noticeably different colour response, and this is believed to bedue to the co-ordinately bound zinc having sufficient ionic character in chloroform to formrapidly the zinc dithizone complex. Test 7 (see p. 324) briefly describes the response frommancozeb as a bright pink "flash" and that from the other products as being slower, duller and more feeble. It is important to note that the 'flash' collectively describes three processesoccurring in rapid sequence at the powder spot on adding the dithizone reagent, i.e. (i) Theappearance of a bright pink colour.
(ii) The transient existence of the colour due to migration of the material on the filter paperwhich is quickly transferred to the outer edge of the powder spot, forming a halo. Traces ofethanol in the chloroform are responsible for the effect.
(iii) The re-appearance of the background colour of the powder spot as process (ii) takes place.
This gives the illusion of the spot emerging from the surface of the paper. These processes arerepeatable by over-spotting with reagent.
MT 133 DETERMINATION OF NITROPHENOLS - TITANIUM(III) CHLORIDE
OUTLINE OF METHODThe nitro groups are reduced with a known excess of titanium(III) chloride and the excess istitrated with standard iron(III) chloride solution.
MT 134 PREPARATION OF 2-PYRIDYLAMINE (2-AMINOPYRIDINE)
COMPLEXES OF NITRO COMPOUNDS
134.1 Technical nitrophenols
134.2 Technical nitrophenol esters
OUTLINE OF METHODThe ester is converted with butylamine and hydrochloric acid to the phenol. The phenol isextracted with hexane and the 2-pyridylamine complex prepared as in MT 134.1.
MT 137 IDENTIFICATION OF UREA HERBICIDES
OUTLINE OF METHODThe urea herbicides present in both technical materials and dispersible powders aredistinguished and identified by reverse phase TLC separation of the active ingredient, usingparaffin impregnated silica gel plates and developing with ethanol + water. Alternatively, or forconfirmation of identity, the separation may be performed on silica gel plates with chloroform +acetone or chloroform + ethyl acetate as developing solvents.
MT 139 POUR POINT OF MINERAL OIL
SCOPEThe test for pour point is intended for use on any petroleum oil (Note 1).
OUTLINE OF METHODAfter preliminary heating the sample is cooled at a specified rate and examined at intervals of3°C for flow characteristics. The lowest temperature at which movement of the oil is observed isrecorded as the pour point.
MT 141 DETERMINATION OF FREE AMINES IN UREA HERBICIDES
OUTLINE OF METHODThe herbicide is dispersed in hydrochloric acid and extracted with chloroform, the free aminesbeing retained in the acid layer. The free aromatic amines are determined by bromination andthe free aliphatic by distillation into hydrochloric acid, which is back titrated with standardsodium hydroxide.
MT 142 DETECTION AND IDENTIFICATION OF IMPURITIES IN SUBSTITUTED
PHENYLUREA HERBICIDES
OUTLINE OF METHODThe phenylurea herbicides are separated from impurities by thin layer chromatography andthe impurities are estimated by visual comparison with standards on the same plate.
MT 145 ACTIVE INGREDIENTS CONTAINING PHOSPHORUS
Spectrophotometric determination as molybdovanadophosphate after TLC separation OUTLINE OF METHODThe method is applicable only if the substance to be determined can be separated from othercomponents of the sample by TLC in such an amount that the area of the silica gel layer usedfor the determination contains approximately 200-400 µg of phosphorus. The substance to bedetermined is separated from manufacturing impurities and added modifying agents by TLCon aluminium foils coated with silica gel. The area containing the active ingredient is cut outand the active ingredient is converted to inorganic phosphate with sulphuric acid andhydrogen peroxide. The phosphate formed is determined colorimetrically as themolybdovanado complex.
MT 146 'OIL CONTENT' OF EMULSIFIABLE PESTICIDE CONCENTRATES
OUTLINE OF METHODThe weighed sample is eluted through a mixed bed of macro reticular anion and cationexchange resins with pentane as solvent. The eluate is evaporated free of solvent, and theresidue is expressed as a percentage of the original sample.
MT 147 RETENTION TEST FOR SEED TREATMENT POWDERS USED ON
CEREAL SEEDS
OUTLINE OF METHODThe seeds are treated with the seed treatment powder by the adhesion test (MT 83). Thetreated seeds are then dropped down a cylinder of specified height on to a sieve. This isrepeated five times and the active ingredient remaining on the seeds is determined.
MT 148 POURABILITY OF SUSPENSION CONCENTRATES
OUTLINE OF METHODThe suspension concentrate is allowed to stand for a definite time and the amount remainingin the container after a standardized pouring procedure is determined. The container is rinsedand the amount then remaining is determined.
148.1 Pourability of suspension concentrates (revised method)
MT 149 PACKING COLUMNS FOR GAS CHROMATOGRAPHY
MT 151 DETERMINATION OF TCDD IN 2,4,5-T
2,3,7,8-Tetrachlorodibenzo-p-dioxin
151.1 TCDD in 2,4,5-T technical
OUTLINE OF METHODTCDD is extracted from 2,4,5-T constituents with hexane and cleaned up by liquidchromatography. It is subsequently separated by capillary gas chromatography with detectionby low resolution mass spectrometry.
151.2 TCDD in 2,4,5-T technical esters
The TCDD is separated from 2,4,5-T ester constituents by liquid chromatography and issubsequently determined by capillary gas chromatography with detection by low resolutionmass spectrometry.
MT 152 IDENTIFICATION OF AMINES
OUTLINE OF METHODSodium hydroxide is added to the acidic residue in the flask, after determination of thedithiocarbamate content, and the mixture is distilled. The first fraction is collected for colourtests for the presence of dimethylamine. Similar tests are applied to the alkaline residue in theflask for the presence of ethylenediamine and propylenediamine.
MT 153 QUALITATIVE PROCEDURE FOR CONFIRMATION OF THE PRESENCE
OF A DITHIOCARBAMATE OR THIURAM
DISULPHIDE
OUTLINE OF METHODThe presence of a dithiocarbamate and/or a thiuram disulphide, e.g. thiram, is confirmed bythe evolution of carbon disulphide when the sample is decomposed with sulphuric acid.
153.1 Liquids
153.2 Solids
MT 154 IDENTIFICATION OF DITHIOCARBAMATE ANIONS
154.1 Zinc dithiocarbamates - Identification by TLC
The dithiocarbamate is decomposed by alkaline EDTA. The anions are separated on silica geland visualized as their copper complexes.
MT 155 ANALYTICAL HPLC METHOD FOR DETERMINATION OF PHENOLIC
IMPURITIES IN PHENOXYALKANOIC HERBICIDES
155.1 Ultraviolet Detector Method
OUTLINE OF METHODThe phenolic impurities are separated on a reverse phase (µ Bondapak C18) column usingmethanol/acetate buffer solution 45 + 55 as mobile phase. Detection is performed byultraviolet absorption at 280 nm. The determination is carried out by an external standardtechnique. The identification of the chlorinated phenols is verified by separating samples andspiked samples with eluant(s) of varying pHs.
155.2 Electrochemical Detector Method
OUTLINE OF METHODThe phenolic impurities (and the active ingredients) are separated on a reverse phase columnusing methanol/acetonitrile/buffer as mobile phase. Phenolic impurities are detected with anelectrochemical detector at +0.9 V. Determination is carried out by using 4-bromo-2-chlorophenol as internal standard. Identification of the impurities is confirmed by spiking,and/or analyzing samples and spiked samples with eluant(s) of alternative pH value(s) (SeeCIPAC 1C pp. 2091 and 2160). Determination of active ingredients can also be done by UV-detection at 280nm using 2-(2,4-dibromo-phenoxy)propionic acid as internal standard.
MT 157 WATER SOLUBILITY
At the test temperature a saturated aqueous solution of the test substance is prepared, and themass concentration is determined using a suitable analytical method.
157.1 Preliminary Test
157.2 Column Elution Method (Solubility less than 10-2 g/l)
OUTLINE OF METHODThis method is based on the elution of the test substance with water at constant temperaturefrom a column charged with the substance which is finely distributed on an inert supportmaterial. The flow rate of the water should be adjusted so that a saturated solution leaves thecolumn. Saturation is achieved when, in consecutive fractions of the eluate at different flowrates, the mass concentration - determined by a suitable method - is constant. This is shownby a plateau when the concentration is plotted against time or eluted volume.
157.3 Flask Method (Solubility above 10-2 g/l)
OUTLINE OF METHODThe test substance is thoroughly distributed in water at 20°C. In a fraction of the suspension,any suspended particles are separated and the concentration of the test substance in the clearsolution is determined, using a suitable analytical procedure. Saturation is attained when nosignificant difference in concentration is found in consecutive tests, and after doubling thetime intervals used for the adjustment of equilibrium.
MT 158 DETERMINATION OF MERCURY ON TREATED SEEDS
OUTLINE OF METHODThe organic matter is destroyed by wet oxidation and the mercury is determinedcolorimetrically with dithizone.
MT 159 POUR AND TAP BULK DENSITY OF GRANULAR
MATERIALS
OUTLINE OF METHODA known weight of sample is put into a glass measuring cylinder and its volume measured.
The cylinder is then raised and allowed to fall vertically through a distance of 25 mm on to arubber pad. The volume is measured again after 100 'taps'.
MT 160 SPONTANEITY OF DISPERSION OF SUSPENSION CONCENTRATES
OUTLINE OF METHODThe method is broadly similar to that used to determine the suspensibility of concentrates(MT 161), except that it employs only one inversion and a 5 min standing time. It involvespreparing 250 ml of a mixture of formulation and water, mixed with only one inversion of themeasuring cylinder. After standing under defined conditions the top nine-tenths is removed,and the remaining tenth assayed chemically, gravimetrically or by solvent extraction. Thespontaneity of dispersion is readily calculated.
MT 161 SUSPENSIBILITY OF AQUEOUS SUSPENSION CONCENTRATES
OUTLINE OF METHODThe method is broadly similar to previously published methods for determining thesuspensibility of wettable powders (e.g. MT 15.1). It involves preparing 250 ml of dilutedsuspension, allowing it to stand in a measuring cylinder under defined conditions, andremoving the top nine-tenths. The remaining tenth is then assayed essayed either chemically,gravimetrically or by solvent extraction, and the suspensibility calculated.
MT 162 DETERMINATION OF ETHYLENETHIOUREA (ETU)
(IMIDAZOLIDINE-2-THIONE)
162.1 HPLC method (Referee method)
OUTLINE OF METHODThe ETU is extracted from the sample with methanol. An aliquot of the methanolic solution isevaporated to dryness and the residue is dissolved in water. The solution is filtered anddiluted, if necessary, and injected on to a column of Nucleosil C18 or Spherisorb ODS. TheETU is eluted with water containing tetrahydrofuran and detected at 233 nm (Note 1).
162.2 Paper chromatographic method
OUTLINE OF METHODThe ETU is extracted from the sample with methanol. Portions of the sample and standardsolutions are spotted on to filter paper and developed with butan-1-ol + ethanol + water. Thechromatogram is sprayed with pentacyanoaminoferroate [PCAF] reagent which produces ablue spot with ETU. The ETU content of the sample is determined by comparing the spotwith those from the standards.
MT 163 IDENTITY TESTS FOR PERMETHRIN, CYPERMETHRIN AND
FENVALERATE
OUTLINE OF METHODThe identity of the active ingredient is established by comparison with the equivalent authenticstandard (Note 1) using at least two of the following techniques, one of which is must bespectroscopic: GLC, HPLC, IR, 13C-NMR, 1H-NMR or MS.
MT 164 IDENTITY TESTS FOR PIRIMICARB, BUPIRIMATE, ETHIRIMOL,
PIRIMIPHOS-METHYL AND PIRIMIPHOS-ETHYL
OUTLINE OF METHODThe identity of the active ingredient is established by a comparison with the equivalent authenticstandard by at least two of the following techniques, one of which must be spectroscopic: GLC,TLC, IR, 1H-NMR.
MT 165 ULTRAVIOLET ABSORPTION TEST FOR EVALUATION OF
ETHYLENEBIS(DITHIOCARBAMATE)
The ultraviolet spectrum is recorded in the range of 200-400 nm on the filtrate of anethylenebis(dithiocarbamate) water dispersion. Absorbance values are measured at 280-285 nmfor the EBDC anion, using a linear baseline procedure.
Zineb, mancozeb, and mixtures of maneb and water-soluble zinc salts give an absorbance notexceeding 0.05 absorbance units, whereas maneb, and mixtures of maneb with zineb or insolublezinc salts give an absorbance higher than 0.05 absorbance units (typically in the range of 0.1 to0.7 absorbance units).
MT 166 SAMPLING OF WATER DISPERSIBLE GRANULES
OUTLINE OF METHODWater dispersible granules (WG) may have a relatively broad particle spectrum so thatsegregation into different particle sizes may occur during transportation or handling of theproducts.
It is, therefore, essential to divide samples with great care. This may be achieved by using adividing apparatus or by standardized manual dividing.
MT 167 WET SIEVING AFTER DISPERSION OF WATER
DISPERSIBLE GRANULES
(See CIPAC MT 59.3)
A sample of water dispersible granules is dispersed in water and the suspension is transferredto a sieve and washed. Determination of the weight of the residue on the sieve is doneaccording to MT 59.3 which has been adapted to the requirements of testing water dispersiblegranules.
MT 169 TAP DENSITY OF WATER DISPERSIBLE GRANULES
1 Standard-method (See CIPAC MT 58.4 and MT 33)
OUTLINE OF METHODThe granules are put into a glass measuring cylinder of known weight which is then raised andallowed to fall vertically through a distance of 2.5 cm on to a rubber pad; the operation isrepeated 50 times and the final volume of powder is measured.
2 Method with dry substance jolting volumeter
OUTLINE OF METHODThe tap density is determined with a Dry Substance Jolting Volumeter according to DIN 53194(Note 1).
MT 170 DRY SIEVE ANALYSIS OF WATER DISPERSIBLE GRANULES
OUTLINE OF METHODSieve analysis consists of the quantitative separation of water dispersible granules into fractionsof different particle size ranges by use of the modified method MT 58.3 (machine sievingdescribed under A). If the apparatus required is not available, a simple method (hand sievingdescribed under B) can be used.
MT 171 DUSTINESS OF GRANULAR PRODUCTS
DEFINITIONDustiness in this method is defined as the property of a granular product to liberate dust into theair when handled under specified conditions. These conditions are related to typical handling inagricultural practice (i.e. measuring out and pouring the product into the spray tank).
OUTLINE OF METHODThe determination of the dustiness of a granular product involves two operations. Firstly, aweighed amount of a granular product is allowed to fall under standard conditions in a testchamber, thus releasing dislodgeable dust. The second operation is the collection and/orassessment of the amount of airborne dust. This can be achieved by a gravimetric method, inwhich the generated dust is removed by an airflow, collected on a filter and weighed, or by anoptical method in which the obscuration of a light-beam by the airborne dust is measured.
MT 172 FLOWABILITY OF WATER DISPERSIBLE GRANULES AFTER HEAT
TEST UNDER PRESSURE
OUTLINE OF METHODAfter the accelerated storage test according to MT 46.1, the amount of granules remaining on asieve is determined without any mechanical disturbance, and afterwards with a standardizedtapping.
MT 173 COLORIMETRIC METHOD FOR DETERMINATION OF THE STABILITY
OF DILUTE EMULSIONS
OUTLINE OF METHODA dye is dissolved in the emulsifiable concentrate formulation (EC). A sample of the dyed ECis added to a standard water to obtain an aqueous emulsion. At the end of a specified time analiquot is withdrawn from the emulsion, and transferred to a flask to which propan-2-ol isadded to clarify the emulsion. Then the absorbance of the dyed solution is measured in aspectrophotometer and compared to the absorbance of a similar aliquot taken under the sameconditions but at t0 (initial emulsion).
MT 174 DISPERSIBILITY OF WATER DISPERSIBLE GRANULES
OUTLINE OF METHODA known amount of a water dispersible granule (WG) is added to a defined volume of waterand mixed by stirring to form a suspension. After standing for a short period, the top nine-tenths are drawn off and the remaining tenth dried and determined gravimetrically. Themethod is virtually a shortened test of suspensibility and is appropriate for establishing theease with which a WG dispersed uniformly in water.
MT 175 DETERMINATION OF SEED-TO-SEED UNIFORMITY OF
DISTRIBUTION FOR LIQUID SEED-TREATMENT FORMULATIONS.
OUTLINE OF THE METHODHigh quality seed (certified seed) of cereals is treated with liquid seed treatment formulationsin a laboratory seed treatment machine which utilises a rotary atomiser to atomise theformulation. The uniformity of the distribution of the formulation from seed to seed isdetermined colorimetrically. The dye present in the formulation being extracted individuallyfrom 100 seeds.
MT 176 DISSOLUTION RATE OF WATER SOLUBLE BAGS
OUTLINE OF METHODAn aqueous suspension of the test powder is prepared. A piece of the bag is immersed in thesuspension for a certain period of time and finally stirred together with the suspension. Thesuspension is then passed through a filter and the flow time is measured or any blockage ofthe filter is observed.
MT 177 SUSPENSIBILITY OF WATER DISPERSIBLE POWDERS
(Simplified method)
OUTLINE OF METHODA suspension of known concentration in standard water or distilled water is prepared, placedin a prescribed measuring cylinder at a constant temperature, and allowed to remainundisturbed for a specified time. The top 9/10ths are removed and the content of activeingredient in the top 9/10ths is determined.
MT 178 ATTRITION RESISTANCE OF GRANULES
OUTLINE OF METHOD Prior to the test the granule is sieved on a 125 µm sieve in order toremove fine particles. A known amount of this dust free granule is transferred to a glass bottleand is then subjected to a rolling movement with an equal amount of glass beads. After rollingfor a specified period of time the attrition resistance is determined by sieving again on a 125µm sieve and weighing the material remaining on the sieve.
178.2 Attrition resistance of dispersible granules
OUTLINE OF METHOD Prior to the test the granules are sieved on a 125 µm sieve in order toremove fine particles. A known amount of this dust free granules is transferred to a glass bottleand is then subjected to a rolling movement. After rolling for a specified period of time theattrition resistance is determined by sieving again on a 125 µm sieve and weighing the materialremaining on the sieve.
MT 179 DISSOLUTION DEGREE AND SOLUTION STABILITY
SCOPE The method is intended for the determination of the degree of dissolution and thestability of solution of water soluble granules.
OUTLINE OF METHOD The SG formulation is dissolved in Standard water in a graduated 250 mlcylinder at 25 °C. After 15 inversions and a standing time of 5 minutes, the contents are poured overa 75 µm sieve. The residue on the sieve is quantified. The stability of the solution is checked byallowing the filtrate to stand for a period of 18 hours and filtering it again through a 75 µm sieve.
MT 180 DISPERSION STABILITY OF SUSPO-EMULSIONS
OUTLINE OF METHODA dispersion of prescribed concentration in Standard Water is prepared and aliquots areplaced in two graduated emulsion tubes, which are then allowed to remain undisturbed forspecified time in a upright and inverted positions at a constant temperature. The dispersioncharacteristics are observed immediately after the preparation of the dispersion, after aspecified time, and after re-dispersion.
MT 181 SOLUBILITY IN ORGANIC SOLVENTS
OUTLINE OF METHODThe solubility - within predefined ranges - of a test substance in organic solvents isdetermined by adding measured volumes of solvent to a known mass of test substance untilcomplete dissolution is observed.
A preliminary test is employed to determine the approximate solubility of the test substance.
The results of the preliminary test are used to select the most appropriate mass of testsubstance for the test.
MT 182 WET SIEVING USING RECYCLED WATER
This procedure is applicable for determining the amount of non-dispersible material in waterdispersible granules.
OUTLINE OF METHODAn aqueous dispersion of the test sample is prepared, poured through a 75 µm sieve, andrinsed using a low volume of water from a re-circulation reservoir. The residue remaining onthe sieve is quantified.
MT 183 THE USE OF THE AGROCHEMICAL EMULSION TESTER (AET)
FOR THE DETERMINATION OF THE STABILITY OF
DILUTE EMULSIONS
SCOPEThe method is suitable for determining the emulsion stability of dilute emulsions at a dilutionrate of 1 %.
OUTLINE OF METHODAn appropriate aliquot amount of the agrochemical emulsion or emulsifiable concentrate isdispersed in CIPAC Standard Hard Water, to provide 250 ml of dilute emulsion. The diluteemulsion is then allowed to flow under gravity through the instrument cell, under controlledconditions, and instrument readings are taken initially and over a 30 minute period.
Instrument readings are dependent on variations in droplet size as the dilute emulsion flowsthrough the cell. Low readings, (typically <1) and stable over time, are indicative of fineuniform droplets, and good emulsion stability. Higher initial readings, (typically >1), whichchange with time, are indicative of coarse, non-uniform droplets and poor emulsion stability.
MT 184 SUSPENSIBILITY OF FORMULATIONS FORMING SUSPENSIONS ON
DILUTION WITH WATER
A suspension of known concentration in CIPAC Standard Water is prepared, placed in aprescribed measuring cylinder at a constant temperature, and allowed to remain undisturbedfor a specified time. The top 9/10ths are drawn off and the remaining 1/10th is then assayedeither chemically, gravimetrically, or by solvent extraction, and the suspensibility calculated.
If the formulation (e.g. WP) is packed in water soluble bags, the suspensibility tests should beperformed in presence of dissolved water soluble bag material.
MT 185 WET SIEVE TEST
SCOPE The method is suitable for the determination of the amount of non-dispersiblematerial in formulations, that are applied as dispersions in water.
OUTLINE OF METHOD A sample of the formulation is dispersed in water and thesuspension formed is transferred to a sieve and washed. The amount of the material retainedon the sieve is determined by drying and weighing.
MT 186 BULK DENSITY
OUTLINE OF METHOD A known weight of a solid material is placed in a glass measuringcylinder and its volume measured (to determine the 'pour density'). The cylinder is then raisedand allowed to fall vertically through a distance of 25 mm on to a rubber pad (50 times) orthis is carried out using a Dry Substance Jolting Volumeter ISO 787 (Note 1). The volume ismeasured again (to determine the 'tap density').
MT 187 PARTICLE SIZE ANALYSIS BY LASER DIFFRACTION
SCOPEThis method provides guidance on the measurement of particle size distributions of cropprotection formulations, for example granules, powders, suspensions and emulsions, throughanalysis of their angular light scattering patterns. Detailed descriptions for the use of laserdiffraction methods are given in ISO 13320-1.
OUTLINE OF THE METHODA representative sample, dispersed at an adequate concentration in a suitable liquid or gas, ispassed through the beam of a monochromatic light source, usually a laser. The light scatteredby the particles at various angles is measured by a multi-element detector and numericalvalues relating to the scattering pattern are then recorded for subsequent analysis. Thesenumerical scattering values are then transformed, using an appropriate optical model andmathematical procedure, to yield the proportion of total volume to a discrete number of sizeclasses forming a volumetric particle size distribution.
MT 188 DETERMINATION OF FREE PARATHION-METHYL IN CS
FORMULATIONS
The method is suitable for determining free parathion-methyl (up to 100 % free activeingredient relative to the total active ingredient content) in CS formulations up to 400 g/kg.
OUTLINE OF METHODA known amount of capsule suspension is mixed with a defined volume of an aqueoussolution containing a non-ionic surfactant. The mixture is stirred for a defined period at adefined temperature. After two centrifugation steps the active ingredient content is determinedin the supernatant.
MT 189 DETERMINATION OF FREE LAMBDA-CYHALOTHRININ CS
FORMULATIONS
SCOPEThis method is intended for use only with lambda-cyhalothrin CS formulations for publichealth applications.
OUTLINE OF METHOD A known quantity of the capsule suspension is transferred to a glassbottle and is then subjected to a rolling movement with a specified amount of hexane with aninternal standard. After rolling for a specified period the concentration of lambda-cyhalothrinin the hexane layer is determined.
MT 190 DETERMINATION OF RELEASE PROPERTIES OF LAMBDA-
CYHALOTHRIN CS FORMULATIONS
SCOPEThis method is intended for use only with lambda-cyhalothrin CS formulations for publichealth applications.
OUTLINE OF METHOD A known quantity of the capsule suspension is transferred to a glassbottle and is then subjected to a rolling movement with a specified amount of a hexane-ethanol mixture with an internal standard. After rolling for three specified periods theconcentrations of lambda-cyhalothrin in the hexane-ethanol layer are determined.
MT 191 ACIDITY OR ALKALINITY OF FORMULATIONS
SCOPEThe method is suitable for determining the acidity or alkalinity of formulated pesticides.
OUTLINE OF METHODThe acidity or alkalinity is determined by titration with standard acid or alkali usingelectrometric end point determination. The titration is carried out in water.
MT 192 VISCOSITY OF LIQUIDS BY ROTATIONAL VISCOMETRY
SCOPEThis method is intended for characterising the flow behaviour of liquid crop protectionformulations. The measurement of non-Newtonian liquids is best carried out by rotationalviscosimeters.
OUTLINE OF METHOD A sample is transferred to a standard measuring system. Themeasurement is carried out under different shear conditions and the apparent viscosities aredetermined. During the test the temperature of the liquid is kept constant.
MT 193 FRIABILITY OF TABLETS
SCOPEThe method is suitable for determined the friability of non-coated tablets under definedconditions. Friability is defined as change of the tablet surface and the refraction by jarringimpact.
OUTLINE OF METHOD The tablets are circulated/turned around in a rotating dish with abuild-in, bow-shaped baffle.

Source: http://www.astm.info/COMMIT/E35_MTMethodsOverview.pdf