Sensitive headspace gas chromatography analysis of free and conjugated 1-methoxy-2-propanol in urine

Abstract

Glycol ethers still continue to be a workplace hazard due to their important use on an industrial scale. Currently, chronic occupational exposures to low levels of xenobiotics become increasingly relevant. Thus, sensitive analytical methods for detecting biomarkers of exposure are of interest in the field of occupational exposure assessment. 1-Methoxy-2-propanol (1M2P) is one of the dominant glycol ethers and the unmetabolized urinary fraction has been identified to be a good biological indicator of exposure. An existing analytical method including a solid-phase extraction and derivatization before GC/FID analysis is available but presents some disadvantages. We present here an alternative method for the determination of urinary 1M2P based on the headspace gas chromatography technique. We determined the 1M2P values by the direct headspace method for 47 samples that had previously been assayed by the solid-phase extraction and derivatization gas chromatography procedure. An inter-method comparison based on a Bland-Altman analysis showed that both techniques can be used interchangeably. The alternative method showed a tenfold lower limit of detection (0.1 mg/L) as well as good accuracy and precision which were determined by several urinary 1M2P analyses carried out on a series of urine samples obtained from a human volunteer study. The within- and between-run precisions were generally about 10%, which corresponds to the usual injection variability. We observed that the differences between the results obtained with both methods are not clinically relevant in comparison to the current biological exposure index of urinary 1M2P. Accordingly, the headspace gas chromatography technique turned out to be a more sensitive, accurate, and simple method for the determination of urinary 1M2P.

Effect of age on toxicokinetics among human volunteers exposed to propylene glycol methyl ether (PGME)

“…linear elimination kinetics). In simulation runs with increasing inhalation exposures, the two models (one that allowed for saturation (our TK model) and one that did not (Tomicic et al, 2010) Regarding the toxicological profiles in young and aging volunteers, age was found to be significant and accounted for about 50% of the total variance in the increasing slope of free PGME (R 2 =0.66, p<0.0001). No difference was detected in total PGME (as the dependent variable) or elimination rates.…”

“…Urine analysis of PGME was performed according to the method of Tomicic and Berode (Tomicic and Berode, 2010). In brief, quantification of urinary PGME included a gas chromatograph (Agilent 6890, Agilent Technologies AG, Urdorf, Switzerland) equipped with a capillary column (CP-Sil 8 CB, 95% dimethylpolysiloxane polymer, 5% phenyl groups; 60 m×0.25 mm i.d., 1.00 µm film thickness Varian Chrompack Milian SA, Geneva, Switzerland), a multipurpose sampler (Gerstel AG, Sursee, Switzerland) operated in headspace mode, and a flame ionization detector.…”