Abstract

In water system, odorous compounds are often associated with the metabolites of microorganisms as fungi and blue-green algae, and the related compounds have been commonly found in lakes and reservoirs. Among those compounds, geosmin (GSM) and 2-methylisoborneol (2-MIB) have been treated as main odor compounds, which cause the off-flavor issues in natural sources such as freshwater, water reservoirs, marine water ecosystems and even in drinking water. Since of the strong smell of GSM and 2-MIB with earthy flavor and odor, they can be simply detected by human nose. Although those compounds are harmless to human health at certain level, high accumulation in natural water and drinking water led to an undesirable odor. Thus, the detection of the presence of those off-flavor compounds is first step to address above problem. To analysis the undesirable odorous compounds in water and aquaculture products, a concise and sensitive method has been developed by using stir bar sorptive extraction-thermal desorption coupled with gas chromatography-mass spectrometry (SBSE-TD-GC-MS) in the study. SBSE-TD-GC-MS has been optimized and validated through analyzing 2-MIB and GSM in aquatic samples. The calibration curves of 2-MIB and GSM were linear in the range of 0.5–100 ng/L (r² > 0.995, RSDs < 3.5%). The limit of detection (LOD, S/N = 3) and limit of quantification (LOQ, S/N = 10) of 2-MIB and GSM were both ~0.2 and 0.5 ng/L, respectively. The recoveries of 2-MIB and GSM were 86–113% with good precision (RSDs < 8%) by spike in 2.5 and 25 ng/L standard compounds. This method was successfully applied to monitor and determinate the amount of 2-MIB and GSM in four types of water samples. Thus, SBSE-TD-GC-MS, a developed technique with high sensitivity and good recoveries, can be applied to detect odorous compounds at very low concentration, by using significantly smaller amounts of water samples, without any pre-concentration.

中文翻译：

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搅拌棒吸附萃取-热解吸-GC-MS联用测定2-甲基异冰片和土臭素水

摘要

在水系统中，臭味化合物常与真菌和蓝藻等微生物的代谢产物相关联，相关化合物已普遍存在于湖泊和水库中。在这些化合物中，土臭素 (GSM) 和 2-甲基异冰片 (2-MIB) 已被视为主要气味化合物，它们会在淡水、水库、海水生态系统甚至饮用水等自然资源中引起异味问题. 由于 GSM 和 2-MIB 的强烈气味带有泥土的味道和气味，它们可以很容易地被人的鼻子察觉。尽管这些化合物在一定程度上对人体健康无害，但在天然水和饮用水中的大量积累会导致难闻的气味。因此，检测这些异味化合物的存在是解决上述问题的第一步。为了分析水和水产养殖产品中的不良气味化合物，本研究采用搅拌棒吸附萃取-热解吸-气相色谱-质谱联用（SBSE-TD-GC-MS）开发了一种简洁灵敏的方法。SBSE-TD-GC-MS 已通过分析水生样品中的 2-MIB 和 GSM 进行了优化和验证。2-MIB 和 GSM 的校准曲线在 0.5–100 ng/L 范围内呈线性（r ² > 0.995，RSD < 3.5%）。2-MIB 和 GSM 的检测限 (LOD, S/N = 3) 和定量限 (LOQ, S/N = 10) 分别为 ~0.2 和 0.5 ng/L。通过加标 2.5 和 25 ng/L 标准化合物，2-MIB 和 GSM 的回收率为 86-113%，具有良好的精密度 (RSD < 8%)。该方法成功应用于监测和测定四种水样中2-MIB和GSM的含量。因此，SBSE-TD-GC-MS 是一种具有高灵敏度和良好回收率的成熟技术，可用于检测极低浓度的有味化合物，只需使用显着较少量的水样，无需任何预浓缩。