The Stability of 2-Chloroethanol in whole blood
Date Issued
2015
Date
2015
Author(s)
Chiang, Chia-Lien
Abstract
2-chloroethanol (2-CE, ethylene chlorohydrin, CAS 107-07-3) is a chemical once widely used in hastening grape vine sprouting among Taiwanese farmers. Due to its severe toxicity upon acute exposure, such use of 2-CE is now prohibited in Taiwan. However, because of its superior potency and cheaper price compared to 49% cyanamide, 2-CE is still being illegally used by some farmers, so cases of poisoning due to accidental ingestions or occupational exposures were reported from time to time. In 2011, a man murdered his ex-girlfriend with 2-CE due to an emotional entanglement in Nantou County; four persons died in this case, and the detection of 2-CE from the corpses was an important forensic evidence. To date, there are no standardized methods for the detection and quantification of 2-CE in human blood, because it is not a routinely-screened toxin. We developed a sensitive and specific method by employing static headspace gas chromatography with mass spectrometry (HS-GC/MS) for the quantitative determination of 2-CE in whole blood sample using 1-pentanol as internal standard. It was performed using selected ion monitoring (SIM) with quantitative ion (m/z 31) and qualitative ion (m/z 49, 80). We found that the method produced results with good linearity (r2=0.999, in the concentration range of 5-200 μg/mL), is sensitive (with the limit of detection and the limit of quantitation as 1 μg/mL and 5 μg/mL, respectively), and is easy to operate. To evaluate the stability of 2-CE, whole human blood samples were taken from 10 volunteers (with EDTA added as anticoagulant), and two different concentrations of 2-CE solutions (10 μg/mL and 100 μg/mL) were prepared from each sample. They were further divided into two groups, with one group stored at 4℃ and another stored at room temperature until analyzed in triplicate by headspace gas chromatography-mass spectrometry (HS-GC/MS). After twelve weeks, the result showed that there were no significant alterations in the concentrations of the 10 μg/mL 2-CE solutions, whether stored at 4℃ (average 10.6 μg/mL with SD 0.86) or room temperature (average 10.5 μg/mL with SD 0.62). In the 100 μg/mL 2-CE solutions, no significant alterations of the concentrations were noticed when stored at 4℃ (average 93.6 μg/mL with SD 5.37); however, when stored at room temperature, it decreased significantly to 78.3 μg/mL in the 9th week and to 83.4 μg/mL in the 12th week. 2-chloroethanol has been assumed to be metabolized to chloroacetaldehyde (CAA) via alcohol dehydrogenase, and then to chloroacetae (CA) by aldehyde dehydrogenase. Both 2-CE and its metabolites should be detected in order to prove that it’s indeed 2-CE poisoning. Looking to the method of determining CA concentration in water for inspiration, we developed a simple and quick way that combines simultaneous liquid-liquid microextraction/methylation and HS-GC/MS for quantification of CA and 2-CE concentrations. Methylation and derivatization were completed in 3 minutes by shaking at room temperature. The methyl ester derivatives and the organic phase were completely volatilized by static headspace technique, and then analyzed by GC/MS. It seems that the concentrations of CA and 2-CE could be simultaneously determined in water, but further evaluations of LOD, LOQ, linearity and yield rate of the method in blood samples are still needed.
Subjects
HS-GC/MS
2-chloroethanol
stability
human whole blood
chloroacetic acid
SDGs
Type
thesis
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