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Reusable Solid-Phase Microextraction Coating for Direct Immersion Whole-Blood Analysis and Extracted Blood Spot Sampling Coupled with Liquid Chromatography–Tandem Mass Spectrometry and Direct Analysis in Real Time–Tandem Mass Spectrometry

2012; American Chemical Society; Volume: 84; Issue: 19 Linguagem: Inglês

10.1021/ac3018229

1520-6882

Fatemeh S. Mirnaghi, Janusz Pawliszyn,

Forensic Toxicology and Drug Analysis

Three different biocompatible polymers were tested and evaluated in order to improve the whole-blood biocompatibility of previously developed C18-polyacrylonitrile (C18-PAN) thin-film solid-phase microextraction (SPME) coating. Among all methods of modification, UV-dried thin PAN-over C18-PAN provided the best results. This coating presented reusable properties and reproducible extraction efficiency for at least 30 direct extractions of diazepam from whole blood [relative standard deviation (RSD) = 12% using external calibration and 4% using isotope dilution calibration]. The amount of absolute recovery for direct immersion analysis and based on the free concentration of diazepam in blood matrix was about 4.8% (desorption efficiency = 98%). The limit of quantitation (LOQ) for the developed solid-phase microextraction liquid chromatography-tandem mass spectrometry (SPME-LC-MS/MS) method for direct whole-blood analysis was 0.5 ng/mL. The optimized modification of the coating was then used for an extracted blood spot (EBS) sampling approach, a new sampling method which is introduced to address the limitations of dried blood spot sampling. EBS was evaluated using LC-MS/MS and direct analysis in real time (DART)-MS/MS, where, for a 5 μL blood spot, LOQs of 0.2 and 1 μg/mL, respectively, were achieved for extraction of diazepam.