Determination of alcohol concentration in a single drop blood obtained via fingertip using gas chromatography/mass spectrometry coupled with solid-phase microextraction

Abstract

This study investigated headspace solid-phase microextraction (HS–SPME)–gas chromatography (GS)/mass spectrometry as a low-complexity method for accurate measurement of blood alcohol concentration (BAC) changes in humans over time following alcohol consumption. The aim was to develop an analytical method that would require as small blood samples as possible—smaller than that required for the conventional method—thereby reducing the burden on the subject. Polyethylene glycol (PEG) was used as the fiber material for SPME, and a DB-WAX capillary column was used for GC. For sample extraction via SPME, 50 µL of blood sample obtained via fingertip puncture was added to a vial already containing 3 mL of 20 % aqueous sodium chloride solution, following which an SPME fiber was inserted into the vapor phase (headspace) of the vial and heated at 70 ℃ for 20 min to sorb ethanol onto the fiber. The experiment for ethanol recovery in whole blood yielded recoveries of 71.1 % when spiked at 100 µg/mL and 95.1 % when spiked at 1000 µg/mL. Blood samples were obtained periodically with consent from a human volunteer who had actually consumed alcohol, and the BAC was shown to decrease with a peak 1.5 h after drinking, confirming the applicability of this method in BAC assessment when compared with the conventional Widmark method. Furthermore, the applicability of this method was also investigated in the case of saliva, which can be collected more easily and non-invasively than blood.