Quantitative determination of peptide drug in human plasma samples at low pg/ml levels using coupled column liquid chromatography–tandem mass spectrometry

Abstract

Plasma concentrations after administration of peptide drugs are often low due to the high potency often seen with this class of compounds. In this work a bioanalytical method based on coupled column liquid chromatography–tandem mass spectrometry (LC–MS/MS) is presented for quantification of a peptide drug, FE 202158, under clinical development. A volume of 0.5 ml human plasma is solid phase extracted on a weak cationic exchanger. After evaporation of the solvent to dryness, the reconstituted sample is injected into a coupled column liquid chromatography system. A heart-cut from the initial column, a cyano column, is trapped on a C 4 column and thereafter injected into a microbore C 18 column. For the detection a triple quadrupole mass spectrometer, equipped with a TurboIonSpray interface working in positive ion mode, is used. The design of the system is described and the gain in sensitivity and selectivity, compared to a conventional system, is discussed. Data from validation of the bioanalytical method are presented. For human plasma samples a lower limit of quantification (LLOQ) of 5.00 pg/ml (=4.77 pmol/l) was achieved. The inter-assay precision was less than 11% and bias was within ±4% over the whole validated range of 5.00–860 pg/ml.