A new automated gas chromatography/solid phase microextraction procedure for determining α-fluoro-β-alanine in urine

In industrial hygiene, biomarkers maintain their promise to reveal the true extent of occupational exposure. The environmental limit values proposed by industrial hygienist associations are more than biological, health-based values indicating professional hazards to humans. High-throughput screening of samples is therefore the strategy of choice to detect occupational exposure biomarkers, yet it requires user-friendly apparatus that give relatively prompt results while ensuring high degrees of selectivity, precision, accuracy and automation, particularly in preparation processes. In light of the above, this contribution describes a novel gas chromatography/triple quadrupole mass spectrometry/positive chemical ionisation approach for determining urinary α-fluoro-β-alanine, a metabolite of 5-fluorouracil, the most widely employed antineoplastic drug. In this new procedure chromatography’s sensitivity is combined with the user-friendliness of alkyl chloroformate/trialkyloxonium on-sample derivatizations followed by solid-phase microextraction sampling, to which is added the quantitative accuracy afforded using a specific isotope-labelled internal standard. The quantification limit for α-fluoro-β-alanine was 25.4 µg/L. Intra- (3.8%) and inter-session (4.5%) repeatability was also evaluated. This method serves to identify suitable risk-control strategies for occupational hygiene conservation programs.