Simultaneous Determination of Rosuvastatin and N-Desmethylrosuvastatin in Human Plasma using Negative Ion ESI-LC/MS/MS Linge Li, William Mylott, Bruce Hidy, and Rand Jenkins • PPD, Richmond, Virginia INTRODUCTION SUMMARY OF BIOANALYTICAL METHOD Calculations Figure 2. Plasma Blank with Internal Standard
A bioanalytical method was developed for the
Validation Samples
Calibration curves were constructed using the
analysis of rosuvastatin, N-desmethylrosuvastatin,
chromatographic peak area ratios of the analyte and
and their respective isotope-labeled internal
Calibration standards were prepared in human plasma
internal standard from the calibration standards by applying
at eight concentration levels spanning the quantitation
a quadratic, 1/concentration squared (1/c2) weighted
dipotassium EDTA. Samples were processed
ranges. Quality control (QC) pools containing the
regression algorithm. Analyte concentrations in unknown
through mixed-mode solid phase extraction using
analytes were prepared in human plasma at the lower
samples were then calculated from their peak area ratios
a Waters Oasis MAX SPE 10-mg, 96-well plate.
limit of quantitation and five concentrations spanning
Analysis was performed with a Sciex API4000, triple
the quantitation range for the evaluation of assay
performance, stability, and recovery.
TurboIonSpray source. Negative ions, formed by
Table 1. Regression Equations
deprotonation of the analyte molecules, were measured using multiple reaction monitoring (MRM)
Extraction Method
mode. The mass transitions monitored were m/z 480Æ340 (rosuvastatin) and m/z 466Æ362 (N-
Sample aliquots (250 µL) were diluted with 75 µL of
water and 350 µL of 2% ammonium hydroxide and
approximately 6.0 minutes. The assay was validated
fortified with 25 µL of working internal standard
solution. Analytes were isolated through mixed-mode
solid phase extraction using a Waters Oasis MAX SPE
0.0500 to 25.0 ng/mL for N-desmethylrosuvastatin
10-mg, 96-well plate and eluted with 500 µL of 2:98
and requires a 250-µL sample aliquot. Samples are
formic acid/acetonitrile, v/v. The eluate was
kept frozen at -70 °C prior to analysis.
Figure 3. Lower Limit of Quantitation Standard
evaporated under a nitrogen stream at 45 °C, and the
A validation was performed to evaluate the
remaining residue was reconstituted with 250 µL of
specificity, precision, accuracy, recovery, and
stability characteristics of the assay. The validation
Table 2. Inter-assay Precision and Accuracy
data presented demonstrate that the assay meets the performance requirements needed to support its
Chromatographic and Mass Spectrometric Conditions Figure 1. Chemical Structures
Sample extracts (25 µL) were injected onto a Waters
ACQUITY UPLC BEH HILIC analytical column
(2.1 mm x 50 mm, 1.7 µm) connected to an
LC/MS/MS system. Mobile Phase A was 2.5 mM ammonium bicarbonate in 98:2:0.01
water/acetonitrile/ammonium hydroxide, v/v/v. Mobile
Phase B was 2.5 mM ammonium bicarbonate in
2:98:0.01 water/acetonitrile/ ammonium hydroxide,
v/v/v. Mobile phase composition was controlled
The analytes were detected by multiple reaction
CONCLUSIONS
monitoring on a Sciex API 4000 triple quadrupole
mass spectrometer using negative ion TurboIonSpray.
Table 3. Stability Summary
An LC/MS/MS assay has been successfully developed and validated for the
Retention times for the analytes and their labeled
determination of rosuvastatin and N-desmethylrosuvastatin in human plasma
internal standards were approximately 2 min.
containing dipotassium EDTA. The assay is suitable for the analysis of
clinical study samples as demonstrated by its specificity, precision, accuracy,
recovery, and stability characteristics.
The assay was validated over three separate
ACKNOWLEDGMENTS
validation runs. Representative results of the
validation are summarized in the following tables.
Margaret L. Ware’s contribution to the poster
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