Gas chromatographic method for the sensitive determination of 2,5-hexanedione using electron capture and mass-selective detection

2,5-Hexanedione (2,5HD) is the principle metabolite of n-hexane and methyl ethyl ketone in human urine. In this paper, a rapid and highly sensitive me thod for the determination of urinary 2,5HD by gas chromatography-electron capture detection and gas chromatography-mass selective detection is descri bed. The method comprises, optionally, acid hydrolysis before the analyte i s being derivitized with 2,4,6-trichlorophenyl hydrazine (TCPH) towards the formation of a chlorinated hydrazone derivative for 2,5HD analysis. The re action conditions such as temperature, time, reagent concentration and pH w ere optimized properly. The detection limit of the method - defined as sign al to noise ratio = 3 - is as low as 0.4 and 1.5 muM using the ECD and MSD (SIM mode), respectively. The linearity of the detection systems extends up to 50 muM of 2,5HD with correlation coefficients better than 0.9995. The w ithin-day and between-day reproducibility for a urine sample of 10 muM in 2 ,5HD were 2.6 and 3.2%, respectively. Spiked pooled samples with various co ncentrations in the range 5-10 muM were processed following the proposed pr ocedure. The recovery was satisfactory enough ranging from 92 to 104%. The method was applied to the analysis of urine samples received from people wo rking in a chemical laboratory and the results revealed variable, yet low c oncentrations of 2,5HD in the hydrolyzed samples. (C) 2001 Elsevier Science B.V. All rights reserved.