Application of On-Line Electrochemical Derivatization Coupled with High-Performance Liquid Chromatography Electrospray Ionization Mass Spectrometry for Detection and Quantitation of (p-Chlorophenyl)aniline in Biological Samples

摘要

A rapid, sensitive, and specific assay for detection and quantitation of (p-chlorophenyl)aniline (CPA) in biological samples was developed. The assay was established based on rapid electrochemical oxidation of CPA to a dimerized product (1.0 V vs Pd) with the enhanced detection sensitivity of electrospray mass spectrometer (ES/MS). A "head-to-tail" dimer ([M + H]~(+) at m/z 217) was exhibited as the predominant species after electrochemical conversion of CPA. Optimal detection sensitivity and specificity for the dimer of CPA that was present in the biological matrix (e.g., rat urine) were achieved through on-line electrochemistry (EC) coupled with high-performance liquid chromatography tandem mass spectrometry. No matrix-associated ion suppression was observed. The limit of detection (S/N approx6) was 20 ng/mL, and the limit of quantitation was 50 ng/mL. The calibration curve was exhibited to be quadratic over the range of 50-2000 ng/mL with r~(2) > 0.99 in various biological matrixes. The assay was validated and used to study the biotransformation of p-chlorophenyl isocyanate (CPIC) to CPA in rats administered intraperitoneally with CPIC (50 mg/kg). The present LC/EC/MS/MS assay of CPA brings important technical advantages to assist in the risk assessment of new chemical entities, which have the potential to produce anilines via biotransformation.