Rapid screening and confirmation of antidepressants in blood using automated solid phase extraction and liquid chromatography-time-of-flight mass spectrometry

Abstract

A high-throughput method was developed for screening antidepressants in blood by automated solid phase extraction and liquid chromatography with high resolution quadrupole-time-of-flight mass spectrometry (ASPE-LC-Q-TOF/MS). The samples were cleaned up by an HLB solid phase extraction cartridge and analyzed by LC-Q-TOF/MS under electrospray ionization (ESI) mode with scanning range of m/z 50-1 000 Da. The chromatographic separation was performed on an Agilent Eclipse Plus C18 column (50 mm x 2.1 mm, 1.8 microm) with gradient elution using methanol and 5 mmol/L ammonium formate aqueous solution (containing 0.2% formic acid) as mobile phases. Rapid screening and confirmation can be achieved using MS matching scores, deviation of retention time, measured mass, isotopic abundance matching scores, isotope space matching scores and MS/MS matching scores. The quantitative analysis was carried out by correlating the extracting peak area with accurate mass. Good linearities were observed in the range of 1 - 500 microg/L with the correlation coefficients from 0.997 6 to 0.999 7. The limits of detection were 0.01-0.5 microg/L. The spiked recoveries were 79.6%-96.4% with the relative standard deviations of 4.1% - 6.4%. The result screening database was built using Agilent MassHunter PCDL Manager software and then used for the analysis of spiked samples. MS matching scores, isotopic abundance matching scores, isotope space matching scores (all > 95 points) and MS/MS matching scores (> 70 points) were applied to identify the analytes. The results showed that all the spiked antidepressants could be correctly identified with low deviation of retention time (< 0.1 min) and mass (< 1 mDa). The developed method was further applied for the analysis of poisoning cases, and amitriptyline, carbamazepine, doxepin were detected. In brief, the method is rapid, sensitive, simple, reliable, and suitable for the screening and confirmation of antidepressants in forensic and clinical analytical toxicology.