Department of Chemical Engineering, Environmental Engineering Program, Yale University, New Haven, Connecticut 06520, USA.
Environ Sci Technol. 2010 May 1;44(9):3369-75. doi: 10.1021/es100361f.
Although N-nitrosodimethylamine (NDMA) has been the most prevalent N-nitrosamine detected in disinfected waters, it remains unclear whether NDMA is indeed the most significant N-nitrosamine or just one representative of a larger pool of N-nitrosamines. A widely used assay applied to quantify nitrite, S-nitrosothiols, and N-nitrosamines in biological samples involves their reduction to nitric oxide by acidic tri-iodide, followed by chemiluminescent detection of the evolved nitric oxide in the gas phase. We here describe an adaptation of this method for analyzing total N-nitrosamine (TONO) concentrations in disinfected pools. Optimal sensitivity for N-nitrosamines was obtained using a reduction solution containing 13.5 mL glacial acetic acid and 1 mL of an aqueous 540 g/L iodide and 114 g/L iodine solution held at 80 degrees C. The method detection limit for N-nitrosamines was 110 nM using 100 microL sample injections and NDMA as a standard. N-nitrosamines featuring a range of polarities were converted to nitric oxide with 75-103% efficiency compared to NDMA. Evaluation of potential interfering species indicated that only nitrite and S-nitrosothiols were a concern, but both interferences were effectively eliminated using group-specific sample pretreatments previously employed for biological samples. To evaluate the low TONO concentrations anticipated for pools, 1 L samples were extracted by continuous liquid-liquid extraction with ethyl acetate for 24 h, and concentrated to 1 mL. N-nitrosamine recovery during extraction ranged from 37-75%, and there was a potential for artifactual nitrosation of amines during solvent reflux in the presence of significant nitrite concentrations, but not at the low nitrite concentrations prevalent in most pools. Using the 1000-fold concentration factor and 56% average extraction efficiency, the method detection limit would be 62 pM (5 ng/L as NDMA). The TONO assay was applied to six pools and their common tap water source in conjunction with analysis for specific nitrosamines. Even accounting for the range of N-nitrosamine extraction recoveries, NDMA accounted for an average of only 13% (range 3-46%) of the total nitrosamine pool.
虽然 N-亚硝基二甲胺（NDMA）是已在消毒水中检测到的最普遍的 N-亚硝胺，但仍不清楚 NDMA 是否确实是最重要的 N-亚硝胺，还是只是更大 pool 中的一种代表。一种广泛用于定量生物样本中亚硝酸盐、S-亚硝基硫醇和 N-亚硝胺的测定方法涉及用酸性三碘化物将其还原为一氧化氮，然后在气相中通过化学发光检测衍生的一氧化氮。我们在此描述了一种适应该方法的方法，用于分析消毒池中的总 N-亚硝胺（TONO）浓度。使用包含 13.5 毫升冰醋酸和 1 毫升 540 克/升碘化物和 114 克/升碘水溶液的还原溶液可获得对 N-亚硝胺的最佳灵敏度，该溶液在 80 摄氏度下保持。使用 100 微升样品注射，以 NDMA 为标准，N-亚硝胺的方法检测限为 110 nM。与 NDMA 相比，具有不同极性的 N-亚硝胺的转化率为一氧化氮的 75-103%。对潜在干扰物质的评估表明，只有亚硝酸盐和 S-亚硝基硫醇是一个问题，但通过以前用于生物样品的特定于组的样品预处理可以有效消除这两种干扰。为了评估预期的池低 TONO 浓度，用乙酸乙酯连续液-液萃取 1 升样品 24 小时，浓缩至 1 毫升。萃取过程中 N-亚硝胺的回收率为 37-75%，在存在大量亚硝酸盐浓度的情况下，在溶剂回流过程中存在人为亚硝化胺的潜在风险，但在大多数池中的低亚硝酸盐浓度下不存在这种风险。使用 1000 倍的浓缩因子和 56%的平均萃取效率，方法检测限将为 62 pM（5 ng/L 为 NDMA）。TONO 测定法与特定的亚硝胺一起应用于六个池及其共同的自来水水源。即使考虑到 N-亚硝胺萃取回收率的范围，NDMA 平均仅占总亚硝胺池的 13%（范围为 3-46%）。
