3.1 Method evaluation
The separation of imatinib and IS was satisfactory and free of
interfering peaks in the biological matrix. The retention time of
imatinib and IS was 1.4 and 2.5 min, respectively (Figure 2). There was
a good linear relationship between the concentration of imatinib
(10-2000 ng/mL) in plasma and the ratio of peak area with
R2 greater than 0.99. The intra-batch and inter-batch
precision, expressed as RSD%, about 10, 30, 300 and 1800 ng/mL QC
samples were less than 4.72%. Accuracy for intra-batch and inter-batch
assays ranged from 105.07-108.60% (Table 1). The matrix effect for 30,
300 and 1800 ng/mL imatinib and IS were
106.36±3.98%、104.38±2.37%、102.22±3.39%、99.92±2.01%, along with
RSD% less than 3.8%. The recovery were 100.76±3.08%, 104.21±3.30%,
102.68±3.65% and 99.01±4.39%, respectively. The RSD values were less
than 3.6%. The stability of imatinib at different conditions conformed
to the verification guidelines of biological sample quantitative
analysis methods, and the RSD values were less than 5.83%. The accuracy
ranged from 92.17 to 105.96%. In addition, work-solution stability of
imatinib for 14 days was also assessed and the accuracy was within ±15%
(Table 2). The average accuracy was 107.36% for 10-fold dilutions with
RSD values less than 3.2%. The imatinib Cssmin would
not be affected as plasma samples processed with dilution pre-treatment.