Improved solid-phase microextraction extraction procedure to detect trace-level epichlorohydrin in municipal water systems by HS-SPME-GC/MS

Epichlorohydrin (ECH) is toxic to humans via multiple routes and is a potential carcinogen. The accurate measurement of ECH at trace level (< 0.1 mu g/L) is still an obstacle hindering the monitoring and regulation of municipal water systems. In this study, an improved headspace solid-phase microextraction (HS-SPME) procedure is developed and optimized to extract and enrich ECH with high sensitivity, accuracy, and precision. A total 17.4-time enhancement in extraction efficiency is achieved compared with the default condition. Specifically, the AC/PDMS/DVB fiber offered a 4.4-time enhancement comparing with the PDMS/DVB fiber. The effects of different mineral salts in SPME were studied and it was found that an addition of 3 g Na2SO4 in the SPME head achieved an additional 3.3-time increase. The pattern how sodium sulfate enhanced ECH extraction by salting out is discussed. The optimization of extraction conditions (pH = 7, 35 & DEG;C, and 20 min extraction duration) brought another 1.2 times further. Combined with gas chromatography with mass spectrometry, the optimized method exhibits curve linearity in the range of 0.02-1.00 mu g/L with an R-2 of 0.998. The limit of detection, precision, and accuracy of the method are 0.006 mu g/L, 2.6%-5.3%, and -3.5% to -2.0%, respectively. The recovery of ECH spiking in tap water and surface water was investigated, with recovery rates of 88.0%-116% and 72.5%-108%, respectively. Adhering to the requirements of existing water quality regulations, our method shows a high potential to be applied in drinking water quality monitoring and water treatment process assessment.

Automated summary

In this study, an improved headspace solid-phase microextraction (HS-SPME) procedure was developed to extract and enrich trace amounts of Epichlorohydrin (ECH) with high sensitivity and accuracy. The optimized method, combined with gas chromatography with mass spectrometry, showed excellent linearity and precision. The method has a high potential for application in drinking water quality monitoring and water treatment process assessment.