Determination of monofluoroacetic acid in plasma and urine by stable isotope dilution ion chromatography-triple quadrupole mass spectrometry

Abstract

A method was developed for the determination of monofluoroacetic acid (MFA) in plasma and urine by ion chromatography-triple quadrupole mass spectrometry (IC-MS/MS). A plasma sample was extracted with 3% (v/v) perchloric acid aqueous solution, and the extract was centrifuged to remove the protein and lipids. A urine sample was acidulated with 3% (v/v) perchloric acid aqueous solution. The target analyte was extracted with methyl tert-butyl ether (MTBE) at a pH between 0.5 and 1.0. After the MTBE was removed by blowing with nitrogen, the MFA in the residues was dissolved into 0.1% (v/v) ammonia solution. The separation of MFA was carried out on a Dionex Ionpac AS 19 analytical column (250 mm×2 mm, 7.5 μm) with gradient elution using KOH solution electrolytically generated from an on-line eluent generation cartridge. Before the eluent flow entered the mass spectrometer, an in-line suppressor was used to remove potassium ions. The MFA was detected with a negative electrospray ionization source in the multiple reaction monitoring (MRM) mode, and quantified with the stable isotope internal standard method. The correlation coefficient of the linear calibration curve of MFA was greater than 0.999 at the corresponding ranges of 0.1-1000 μg/L. The average recoveries were 96.2%-120% of MFA in plasma and urine samples with relative standard deviations of 1.1%-13.1% (n=6). The limits of detection of MFA in plasma and urine samples were 0.03 μg/L and 0.1 μg/L, respectively. The method is simple, sensitive and accurate, and can be applied for the determination of MFA in plasma and urine samples.