Accurate determination of highly volatile chloroethylene by quantitative 1H-NMR

Abstract

In Japan, chloroethylene is a regulated substance under the soil contamination countermeasures act since 2017, due to the presence of chloroethylene in soil leachate and groundwater. As a consequence, chloroethylene concentrations must be accurately determined to ensure the safety of drinking water, chloroethylene standard solutions with reliable concentrations had not been available because chloroethylene is difficult to handle due to its boiling point of − 13 °C. Here, we developed a quantitative 1H nuclear magnetic resonance (1H-qNMR) method to measure chloroethylene concentration in a standard solution in CD3OD. Sampling temperature must be between − 80 °C and − 21 °C, and the NMR tube headspace volume ratio must be lower than 23% to reduce the volatilization of chloroethylene. We used the signal of CD2HOD present in the standard solution as an internal standard because chloroethylene was volatilized during the addition of another internal standard. The chloroethylene concentration in the standard solution was accurately determined as 117.7 ± 1.4 mg kg−1.