Development of a headspace gas chromatographic test for the quantification of 1- and 2-bromopropane in human urine

Development and validation of determination of genotoxic impurity Bromoethane in Vigabatrin drug substance using head space gas chromatographic method [HS-GC]

A specific HS-GC method has been developed, optimized, and validated for the determination of genotoxic impurity Bromoethane in Vigabatrin (VGB) drug substance. Chromatographic separation of genotoxic Bromoethane impurity was achieved on DB-1 column (30 m × 0.53 mm, 5.0 μm), consists of 100% dimethyl polysiloxane as stationary phase and passing nitrogen carrier gas. The performance of the method was assessed by evaluating the specificity, linearity, sensitivity, precision, and accuracy experiments. The established limit of detection and limit of quantification values for the genotoxic impurity was in the range of 3.57–10.80 μg/mL. The correlation coefficient value of the linearity experiment was 0.9880. The average recoveries for the accuracy were in the range of 95.3–106.8%. The results proved that the method is suitable for the determination of Bromoethane content in Vigabatrin.

Biomarkers of exposure and effect in the serum and urine of rats or workers exposed to 1-bromopropane

Extensively used in several industries in China as a cleaning agent, 1-bromopropane (1-BP) has significant adverse effects on the central nervous system. However, neither its mechanism of action nor sensitive biomarkers related to it have been determined thus far. In this study, animal experiments and occupational surveys were performed to explore the typical exposure and effect biomarkers of neurotoxicity induced by 1-BP. Male Wistar rats were exposed to 0, 500, or 1000 ppm of 1-BP followed by pathological and biomarker analyses. An epidemiological survey was conducted on 71 workers each from 1-BP exposed and control groups. Serum and urine samples were collected for biomarker testing. cNSE represents neuron-specific enolase (NSE) in the cerebral cortex, where as sNSE represents NSE in the serum; similar terminology applies to S-100β, and cyclooxygenase-2 (COX-2). In rats exposed to 1000 ppm 1-BP, pathological changes were observed in Purkinje cells, lumbar gray matter, and tibiofibular nerve, while levels of cNSE, cS-100β, cCOX-2, sS-100β, and sCOX-2 were significantly elevated at different time checkpoints. In the 500 ppm group, cCOX-2, sNSE, and sCOX-2 levels were significantly elevated at different time checkpoints. 1-BP and N-acetyl-S-(n-propyl)-L-cysteine (AcPrCys) were detected in rat urine, and there was a correlation between the level of sNSE or sCOX-2 and AcPrCys in the 500 ppm group. In the occupational epidemiological study, a significant correlation between AcPrCys and exposure concentration was also detected. The findings of this study indicated that AcPrCys was a sensitive exposure biomarker of 1-BP in rats as well as occupational populations.

N-acetyl-S-(n-propyl)-l-cysteine in urine from workers exposed to 1-bromopropane in foam cushion spray adhesives

1-Bromopropane (1-BP) has been marketed as an alternative for ozone depleting and other solvents; it is used in aerosol products, adhesives, metal, precision, and electronics cleaning solvents. Mechanisms of toxicity of 1-BP are not fully understood, but it may be a neurological and reproductive toxicant. Sparse exposure information prompted this study using 1-BP air sampling and urinary metabolites. Mercapturic acid conjugates are excreted in urine from 1-BP metabolism involving debromination. Research objectives were to evaluate the utility of urinary N-acetyl-S-(n-propyl)-L-cysteine (AcPrCys) for assessing exposure to 1-BP and compare it to urinary bromide [Br((-))] previously reported for these workers. Forty-eight-hour urine specimens were obtained from 30 workers at two factories where 1-BP spray adhesives were used to construct polyurethane foam seat cushions. Urine specimens were also obtained from 21 unexposed control subjects. All the workers' urine was collected into composite samples representing three time intervals: at work, after work but before bedtime, and upon awakening. Time-weighted average (TWA) geometric mean breathing zone concentrations were 92.4 and 10.5 p.p.m. for spraying and non-spraying jobs, respectively. Urinary AcPrCys showed the same trend as TWA exposures to 1-BP: higher levels were observed for sprayers. Associations of AcPrCys concentrations, adjusted for creatinine, with 1-BP TWA exposure were statistically significant for both sprayers (P < 0.05) and non-sprayers (P < 0.01). Spearman correlation coefficients for AcPrCys and Br((-)) analyses determined from the same urine specimens were highly correlated (P < 0.0001). This study confirms that urinary AcPrCys is an important 1-BP metabolite and an effective biomarker for highly exposed foam cushion workers.