采用SPE-HPLC-MS/MS(APCI源)检测水中纳克级二甲基亚硝胺

Determination of N-dimethylnitrosamine at nanogram level in water by SPE-HPLC-MS/MS(APCI source)method

建立了以固相萃取(SPE)为前处理手段,超高效液相色谱串联结合大气压化学离子源(APCI源)及三重四级杆质谱(HPLC-MS/MS)检测水中痕量级二甲基亚硝胺(NDMA)的方法。试验结果表明,APCI源可以很好地将NDMA离子化,在MRM全扫描模式下,母离子质荷比m/z为75.1,其中m/z为43.3的子离子视为定量离子,m/z为58.2的视为定性离子。以超纯水为定容溶剂,在1~50μg/L的线性范围内的相关性系数为0.996。以椰壳活性炭为吸附剂,在浓缩400倍的条件下对水样进行富集,回收率超过80%,方法检测限为1.12~3.11ng/L。使用该方法对水源水以及出厂水的NDMA进行检测,测得水源水的NDMA浓度低于检测限,出厂水NDMA浓度水平随季节变化不大,浓度为10.65~12.02ng/L,可能与水厂PAM投加有关。

A method, using solid-phase extraction （SPE） as pretreatment and ultra-high-performance-liquid chromatography coupled to a triple quadrupole mass spectrometer （HPLC-MS/MS） equipped with APCI source, was established for trace level determination of N-dimethynitrasamine （NDMA） in water. The experiment results showed that APCI could achieve the ionization of NDMA very well. In MRM acquisition mode, ion with m/z of 75.1 was determined as the precursor ion, in which product ions with m/z of 58.2 and 43.3 were determined as qualitative and quantitative ions respectively. The correlation coefficient of the standard curve （1-50 μg/L） was 0. 996 with ultra-pure water as solvent. The recovery rate was more than 80 % and the limit of detection （LOD） was 1.12-3.11 ng/L, when the water samples were concentrated for 400 times with coconut active charcoal as adsorbent. This method was applied to determine the concentration of NDMA in source water and treated water. The concentration of NDMA in the source water was lower than the LOD. The average NDMA concentration in the treated water was 10. 65-12.02 ng/L without significant seasonal change, which was probably related to PAM dosage.