顶空固相微萃取谱-气相色谱-质谱联用测定饮用水中6种致嗅化合物

Determination of six earthy-m/usty odorous compounds in drinking water by headspace solid-phase microextraction coupled with gas chromatography-mass spectroscopy

采用顶空固相微萃取谱-气相色谱-质谱联用法对饮用水中2-甲基异茨醇、土味素、2-甲氧基-3-异丙基吡嗪、2-甲氧基-3-异丁基吡嗪、2,4,6-三氯苯甲醚和2,3,6-三氯苯甲醚共6种致嗅化合物进行了分析。通过对固相微萃取纤维的类型、解吸附时间、NaCl溶液浓度、溶液pH、顶空温度、转速、顶空时间等顶空条件及GC-MS条件的优化,建立了一次性顶空固相微萃取快速测定饮用水中6种致嗅化合物的方法。采用0.10 mol/L的NaOH溶液将水样调至pH 6.0。以DVB/Carboxen/PDMS涂层的固相微萃取纤维头对20 mL添加了NaCl溶液浓度为0.3 g/mL的水样于70℃水浴顶空萃取25 min。被萃取的致嗅化合物于250℃解吸附4 min供GC-MS分析。6种致嗅化合物在0.25～100 ng/L范围内线性关系良好(R>0.986),检出限低于0.1 ng/L。对实际水样进行分析,低、中、高3种不同浓度的加标回收率为93.0%～106.6%,相对标准偏差为3.0%～6.6%(n=6)。该分析方法可对饮用水中6种致嗅化合物进行同时监测。

A new method for the determination of earthy-musty odorous compounds, 2-methylisoborneol （ MIB）, 2-isobutyl - 3-methoxy pyrazine （ IBMP）, 2-isopropyl - 3-methoxy pyrazine （ IPMP）, 2,4,6-trichloroanisole （ 2,4,6-TCA ）, 2,3,6-trichloroanisole （ 2,3,6-TCA ） and geosmin （ GSM ） in drinking water by headspace solid- phase microextraction （HS-SPME） combined with gas chromatography-mass spectrometry （GC-MS） was described. The conditions for the analysis of earth-musty odorous compounds were optimized by investigating the type of extraction fiber, desorption time, NaCl concentration, solution pH, headspace temperature, stirring speed, headspace time and GC-MS conditions. The DVB/Carboxen/PDMS coating extraction fiber was selected for HS-SPME. The pH of the sample solution was adjusted to 6.0 by 0. 10 mol/L sodium hydroxide solution. Twenty microliter of sample solution with 0. 30 g/mL NaCl was equilibrated at 70 ℃ for 25 min. The extraction fiber was injected into GC-MS at 250 ℃ for 4 min. The earthy-musty odorous compounds were then qualified by selected ion monitoring mode. The earth-musty odorous compounds showed good correlation coefficient （R 〉 0. 986） in the range of 0. 25 ～ 100 ng/L. The limits of detection were lower than 0. 1 ng/L. The method was successfully applied to analysis of earthy and musty odors in real drinking water samples. The relative standard deviations were 3.0% ～ 6.6% （n = 6） and the recoveries of the spiked samples were 93.0% ～ 106. 6%. The new method was simple, convenient, sensitive, and accurate and was suitable for the determination of earthy musty odorous compounds in drinking water.