摘要:
水体中正构烷烃的含量反映了研究区域有机物污染水平。痕量正构烷烃的测定常常需要结合分离富集方法才能保证灵敏度和选择性,液液萃取等常规分离富集方法存在耗时长、有机溶剂使用量大等缺点,而新型固相微萃取(SPME)分离富集技术相比而言具有高效简便、富集效率高的特点。本文采用溶胶-凝胶法自制稳定性和耐基质性能更优的有机-无机杂化SPME涂层,结合气相色谱-质谱(GC-MS)检测技术,对水样中26种正构烷烃进行同时测定。在优化的SPME-GC/MS条件下,采用浸入式萃取方式,萃取温度为25℃,萃取时间为30 min,26种正构烷烃的分析信号与浓度之间有良好的线性关系(线性相关系数为0.9935~0.9999),方法检出限为0.011~0.085 μg/L(k=3),相对标准偏差(RSD,n=5)为3.9%~10.0%。新型有机-无机杂化涂层与传统的分离富集技术相比,减少了有机溶剂的使用,提高了工作效率;与商用PDMS涂层相比,增加了正构烷烃同时检测的种类,提高了灵敏度,检出限低2~10倍。自制的有机-无机杂化SPME涂层体现出优异的分析性能和应用潜力。
Abstract:
Concentrations of n-alkanes in water often indicate the degree of organic pollution in a specific region. Trace n-alkanes analysis is often associated with the separation and enrichment process in order to improve the sensitivity and selectivity of the method. The conventional separation and enrichment methods, such as liquid-liquid extraction, are time-consuming and utilize a large quantity of organic solvents. Conversely, the Solid Phase Microextraction (SPME) technology has the characteristics of high efficiency and high sensitivity. A new method of determining 26 n-alkanes by using a homemade organic-inorganic hybrid solid phase microextraction coating combined with Gas Chromatography-Mass Spectrometry (GC-MS) has been established. The homemade SPME coating produced by the sol-gel method has good stability and is matrix resistant. The optimized analytical conditions were 30 min of extraction at 25℃ in immersion extraction mode. Under the optimized conditions of SPME-GC-MS, analysis signals of all 26 n-alkanes had good linear relationships with the concentration. The linear correlation coefficient r ranged from 0.9935 to 0.9999. The detection limits (k=3) were in the range of 0.011 to 0.085 (μg/L), and the relative standard deviations (RSD, n=5) ranged between 3.9% and 10.0%. The results show that the detection limits of 26 n-alkanes with homemade organic-inorganic hybrid coating were 2-10 times lower than the commercial PDMS coating, and more types of n-alkane were simultaneously determined with high sensitivity. The method is simple, fast, sensitive and easy to use in the determination of n-alkanes. The homemade organic-inorganic hybrid SPME coating shows excellent performance of n-alkanes analysis and potential applications.
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