Liquid-liquid extraction (LLE)

The authors proposed a simple, rapid and sensitive liquid chromatography / tandem mass spectrometry assay method for the determination of nateglinide in human plasma using carbamazepine as internal standard (IS). Analyte and the IS were extracted from the human plasma via liquid-liquid extraction using ethyl acetate. The chromatographic separation was achieved on a C18 column by using a mixture of 0.1% formic acid buffer –acetonitrile buffer (20:80, v/v) as the mobile phase at a flow rate of 0.8 mL/min. The calibration curve obtained was linear (r2 ³ 0.99) over the concentration range of 10.0–10005 ng/mL. Method validation was performed as per FDA guidelines and the results met the acceptance criteria. The proposed method was found to be applicable to pharmacokinetic studies.