GC-MS method for determining faecal sterols as biomarkers of human and pastoral animal presence in freshwater sediments
GC-MS method for determining faecal sterols as biomarkers of human and pastoral animal presence in freshwater sediments
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DOI：
10.1007/s00216-015-8998-2
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发表时间：
2015-11-01
影响因子：
4.3
通讯作者：
Barbante, Carlo
中科院分区：
文献类型：
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作者：
Battistel, Dario;Piazza, Rossano;Barbante, Carlo
为了测定淡水沉积物中的甾醇和甾烷醇，以重建人类和畜牧动物过去的存在，我们开发了一种基于加压液体萃取 (PLE)、固相萃取 (SPE) 净化和气相色谱-质谱 (GCMS) 分析测定甾醇的分析方法。使用二氯甲烷 (DCM) 和 DCM/甲醇混合物优化 PLE 提取条件。使用 2 g 硅胶 SPE 柱进行净化，并使用 70 mL DCM 洗脱浓缩的提取物。使用添加了 C-13 标记胆固醇并陈化 10 天的内部参考材料来评估提取率。与预提取（提取沉积物然后添加已知分析物浓度）相比，这种方法保留了沉积物的原始成分。 DCM 和 DCM/甲醇混合物的提取率高达 86% 至 92%，且重现性良好（相对标准偏差 (RSD) 5-8%）。使用 DCM 作为提取溶剂获得的 PLE 提取率比使用超声波浴的提取率高约 1.5 倍。溶剂萃取混合物和基质组成强烈影响溶剂萃取组成，其中使用 DCM 获得每种化合物更高的总体回收率 (70-80%)。萃取混合物和基质组成也会影响分析物浓度，导致方法精度范围为 1% 至 18%。添加 10 至 100 ng 甾醇的硅藻土以及添加适量甾醇的环境样品提供了 90% 至 110% 的表观回收率。我们将该方法应用于污水排放区附近和上游的环境样本，导致污水附近的粪便甾醇（FeSt）浓度显着升高。此外，我们还将该方法应用于37cm淡水沉积物岩心，以评估其获取垂直甾醇剖面的适用性。
In order to determine sterols and stanols in freshwater sediments to reconstruct the past presence of humans and pastoral animals, we developed an analytical method based on pressurised liquid extraction (PLE), clean-up performed using solid phase extraction (SPE) and sterol determination using gas chromatography-mass spectrometry (GCMS) analysis. PLE extraction conditions were optimised using dichloromethane (DCM) and DCM/methanol mixtures. Clean-up was performed with 2 g silica SPE cartridges, and the concentrated extracts were eluted with 70 mL DCM. Extraction yield was evaluated using an in-house reference material spiked with C-13-labelled cholesterol and aged for 10 days. In comparison with pre-extraction, where the sediment is extracted and then spiked with a known analyte concentration, this approach preserves the original composition of the sediment. DCM and DCM/methanol mixtures resulted in high extraction yields ranging from 86 to 92 % with good reproducibility (relative standard deviation (RSD) 5-8 %). PLE extraction yields obtained with DCM as the extracting solvent were about 1.5 times higher than extractions using an ultrasonic bath. The solvent extraction mixture and matrix composition strongly affected the solvent extraction composition where higher overall recoveries (70-80 %) for each compound were obtained with DCM. The extraction mixture and matrix composition also affected the analyte concentrations, resulting in a method precision ranging from 1 to 18 %. Diatomaceous earth spiked with 10 to 100 ng of sterols, and environmental samples fortified with suitable amounts of sterols provided apparent recovery values ranging from 90 to 110 %. We applied the method to environmental samples both close to and upstream from sewage discharge zones, resulting in substantially higher faecal sterol (FeSt) concentrations near the sewage. In addition, we also applied the method to a 37cm freshwater sediment core in order to evaluate its applicability for obtaining vertical sterol profiles.