Szucs Sándor, Sárváry Attila, Cain Terry, Adány Róza
Department of Preventive Medicine, School of Public Health, Medical and Health Science Centre, University of Debrecen, H-4012 Debrecen, P.O. Box 9, Hungary.
J Chromatogr Sci. 2006 Feb;44(2):70-6. doi: 10.1093/chromsci/44.2.70.
Besides microbiological methods, fecal pollution of surface waters is estimated by gas chromatographic (GC) determination of sterols present in human and animal sewage effluents. The most frequently used biomarkers for the evaluation of contamination levels include coprostanol, cholesterol, dihydrocholesterol, stigmasterol, beta-sitosterol, and stigmastanol. Although several GC techniques are used to measure these compounds in aquatic systems, the analytical performance of GC-mass spectrometric (MS) determination of these sterols has not been systematically characterized. Therefore, the aim of this work is to validate a simple and rapid GC-MS method for the simultaneous analysis of six sterols, considering all parameters and requirements defined by Good Laboratory Practice. Following liquid-liquid extraction of spiked surface water samples, the extracts are silylated and analyzed by GC-MS. The method is evaluated for linearity and limits of detection and quantitation, as well as for precision, extraction efficiency, and stability. The assay is linear up to 160 ng; the limits of detection and quantitation are 5-10 ng and 20 ng, respectively. The within- and between-day precision ranged from 1% to 9% and 1% to 16%, respectively. The extraction efficiency was 65-80%. The stability studies indicate that the sterols in surface water samples begin to degrade after 24 h of refrigerated storage. However, three freeze/thaw cycles could be performed without their decomposition. The method is applied to the analysis of surface water and wastewater samples. The technical advantages make this GC-MS analysis suitable for routine environmental monitoring of fecal pollution in aquatic systems.
除了微生物学方法外，地表水的粪便污染还通过气相色谱（GC）测定人类和动物污水中存在的甾醇来估算。用于评估污染水平的最常用生物标志物包括粪甾醇、胆固醇、二氢胆固醇、豆甾醇、β-谷甾醇和豆甾烷醇。尽管有几种GC技术用于测量水生系统中的这些化合物，但GC-质谱（MS）测定这些甾醇的分析性能尚未得到系统表征。因此，本研究的目的是验证一种简单快速的GC-MS方法，用于同时分析六种甾醇，同时考虑良好实验室规范定义的所有参数和要求。对加标地表水样品进行液-液萃取后，将萃取物进行硅烷化处理并通过GC-MS进行分析。对该方法的线性、检测限和定量限以及精密度、萃取效率和稳定性进行了评估。该测定在高达160 ng时呈线性；检测限和定量限分别为5-10 ng和20 ng。日内和日间精密度分别为1%至9%和1%至16%。萃取效率为65-80%。稳定性研究表明，地表水样品中的甾醇在冷藏储存24小时后开始降解。然而，可以进行三个冻融循环而不发生分解。该方法应用于地表水和废水样品的分析。这些技术优势使得这种GC-MS分析适用于水生系统中粪便污染的常规环境监测。
