Abstract: A method for the determination of deuterium content in drinking water labeled low deuterium by thermal conversion/elemental analysis-isotope ratio mass spectrometry (TC/EA-IRMS) was established. The water sample was filtered through a 0.22 μm filter membrane, and 2 mL of the sample was transferred to a vial. The sample volume was 0.1 μL. The reactor temperature was 1 380 ℃, the column temperature was 85 ℃, and the carrier gas flow rate was 100 mL/min. Each sample was analyzed 4 to 6 times. The accuracy of the calculated deuterium content was improved by eliminating the first data point and the top space of the sample vial to avoid the influence of the void space and memory effect on the measurement of δ2H. This method was suitable for the determination of deuterium content in drinking water within the range of 12.624–155.760 μg/g, and the relative standard deviation (RSD) between the measured and theoretical values was less than 0.6%. The relative deviation (SD) of deuterium content in one deuterium-depleted water sample was 0.08 μg/g for 8 consecutive measurements, and 0.086 μg/g for 3 measurements within 30 days, indicating good repeatability and reproducibility. The RSD for the determination of water samples with low deuterium content by different instrumental methods was lower than 1 μg/g. The deuterium contents of 8 deuterium-depleted packaged drinking waters were tested. Generally, the measured and labeled values were not consistent with each other. Determination of deuterium content in deuterium-depleted water by TC/EA-IRMS can provide technical support and a theoretical basis for supervision and testing of deuterium content in packaged drinking water labeled low deuterium.

Key words: deuterium content; deuterium-depleted packaged drinking water; thermal conversion/elemental analsis-isotopic ratio mass spectrometry; testing and supervision