稳定性同位素稀释吹扫捕集-气质联用法测定水中典型臭味物质

摘要

A stable isotope dilution technique based on purge-and-trap coupled to gas chromatography with mass spectrometric detection was developed and optimized for the trace determination of the typical odorous compounds, geosmin (GSM) and 2-methylisoborneol (MIB). The selection of quantitation ions and the factors of temperature program, the sample purge temperature, salt content on the extraction of odorous compounds were studied. Under the experimental conditions, the optimal operating conditions were the addition of 20％ (m/V) NaC1, purging at 60 ℃ on the temperature program of 5 ℃/min. D5-Geosmin and d3-MIB as the isotopes internal standards were added to improve the stability of recovery. Using this method, both the calibration curves of MIB and GSM were good linear correlation in the range of 5-500 ng/L. Recoveries were 82 ％-95 ％ for GSM and 99％-101％ for MIB, and precision was 5.2％ for GSM and 0.8％ for MIB. The limits of detection for GSM and MIB were 3.6 and 4.1 ng/L, respectively.%采用稳定性同位素稀释吹扫捕集-气相色谱/质谱联用法测定水中典型臭味物质土臭素(GSM)和2-甲基异莰醇(MIB).研究了特征离子、升温程序、样品吹扫温度及盐浓度等因素对臭味物质萃取过程的影响.本实验测定臭味物质的最佳条件为:盐浓度20%(m/V),样品吹扫温度60℃,程序升温速率5℃/min.通过加人同位素内标d5-GSM和d3-MIB,可以提高样品回收率的稳定性.土臭素(GSM)和2-甲基异莰醇(MIB)浓度在5～500 ng/L,范围内线性良好;在100 ng/L加标浓度水平下,GSM和MIB回收率范围分别为82%～95%和99%～101%;相对标准偏差为5.20%和0.78%.方法检出限分别为3.60和4.12 ng/L.本方法操作简单、快速、准确,用于实际水样的检测效果良好.