title: Coupling desorption electrospray ionization with solid-phase microextraction for screening and quantitative analysis of drugs in urine.
abstract: Direct analysis of silica C(18)-coated solid-phase microextraction (SPME) fibers using desorption electrospray ionization mass spectrometry (DESI-MS) for the purpose of analyzing drugs from raw urine is presented. The method combines a simple, inexpensive, and solvent-less sample preparation technique with the specificity and speed of DESI-MS and MS/MS. Extraction of seven drugs from raw urine is performed using specially designed SPME fibers coated uniformly with silica-C(18) stationary phase. Each SPME device is inserted into unprocessed urine under gentle agitation and, then, removed, rinsed, and analyzed directly by DESI-MS (MS/MS). Rapid screening over a wide mass range is afforded by coupling the method with a time of flight (TOF) mass spectrometer while quantitative analysis is performed using selected reaction monitoring (SRM) using a triple quadrupole mass spectrometer. The performance of the SPME DESI-MS/MS method was evaluated by preparing calibration standards and quality control (QC) samples of the seven drug compounds from urine over a range from 20 to 1000 ng/mL, with the exception of meprobamate which was prepared from 200 to 10000 ng/mL. The calibration curves constructed for each analyte had an R(2) > 0.99. The range of precision (%CV) and accuracy values (% bias) for low QC samples was 1-11% and 3-38%, respectively. Precision and accuracy values for high QC samples range from 0.9 to 8% and -31 to -8%. Results from urine specimens of actual exposure to drugs screened using the SPME DESI-MS/MS method showed good agreement with the conventional immunoassays and GC/MS analysis. Liquid desorption of the SPME fiber followed by LC/MS/MS also showed good agreement with the SPME DESI-MS/MS method.
authors.affiliation: Prosolia, Inc., Indianapolis, Indiana, USA.
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Kennedy
authors.forename: Craig
authors.initials: C
authors.lastname: Aurand
authors.forename: Robert
authors.initials: R
authors.lastname: Shirey
authors.forename: Brian C
authors.initials: BC
authors.lastname: Laughlin
authors.forename: Justin M
authors.initials: JM
authors.lastname: Wiseman
mesh_terms: D044707:Forensic Sciences; D006801:Humans; D013287:Illicit Drugs / Q000302:isolation & purification / Q000652:urine*; D052617:Solid Phase Microextraction / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D013287:Illicit Drugs