Internal Standards for Quantitative LC-MS Bioanalysis - LC-MS in Drug Bioanalysis - page 21

a

4

3

2

1

0

0 30 60 90 120

Sample Sequence No.

System Suitability Sample CS and QC Incurred Sample

b

c

Fig. 12 ( a , top ): High internal standard responses were observed for incurred samples only.
Analyte: repaglinide; extraction: automatic liquid-liquid extraction. ( b , middle ): Postelution infu-
sion results show that ion suppression existed near the retention time of the analyte (1.57 min) from
the pooled control blank used for the preparation of calibration standards and quality controls.
( c , bottom ): Absence of ion suppression near the retention time of the analyte in subject predose
sample. Reproduced from ref. [ 36 ] with permission from Elsevier