Synthetic pyrethroids are frequently detected as trace contaminants in sediment and natural waters. Because of the importance of measuring both total and freely available concentrations for ecotoxicity evaluations, solid-phase microextraction (SPME) combined with gas chromatography–mass spectrometry using negative chemical ionization (NCI-GC-MS) was investigated as an analytical technique. Automated SPME-NCI-GC-MS quantification of freely dissolved (and thus potentially bioavailable) pyrethroids in aqueous samples containing dissolved organic matter (DOM) was successfully applied. The introduction of stable isotope-labeled pyrethroid calibration standards into the water sample allows for the simultaneous determination of total concentrations. Because pyrethroids adsorb rapidly to container walls (especially in calibration standard solutions without DOM) it was necessary to develop a technique to minimize the resulting time-dependent losses from calibration standard solutions in autosampler vials as they await analysis. A staggered preparation of these analytical calibration standards immediately prior to analysis was shown to ameliorate this problem. The developed method provides accurate and reproducible results for aqueous samples containing a range of dissolved organic matter concentrations (e.g., sediment pore water or sediment/water mixtures) and yields practical benefits in comparison to conventional analysis methods, such as reduced sample volume requirements, reduced solvent consumption, and fewer sample manipulations, and makes simultaneous measurements of freely dissolved/bioavailable pyrethroids and total pyrethroids possible.

中文翻译：

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用于测量合成拟除虫菊酯的自动固相微萃取和负化学电离 GC-MS

合成拟除虫菊酯经常被检测为沉积物和天然水中的痕量污染物。由于测量总浓度和可自由获得的浓度对生态毒性评估的重要性，将固相微萃取 (SPME) 与使用负化学电离 (NCI-GC-MS) 的气相色谱-质谱联用 (NCI-GC-MS) 作为一种分析技术进行了研究。自动 SPME-NCI-GC-MS 对含有溶解有机物 (DOM) 的水性样品中自由溶解（因此具有潜在生物利用度）的拟除虫菊酯进行定量已成功应用。将稳定同位素标记的拟除虫菊酯校准标准引入水样中，可以同时测定总浓度。由于拟除虫菊酯会迅速吸附到容器壁上（尤其是在不含 DOM 的校准标准溶液中），因此有必要开发一种技术，以最大限度地减少自动进样器样品瓶中校准标准溶液在等待分析时产生的时间依赖性损失。在分析之前立即交错制备这些分析校准标准被证明可以改善这个问题。所开发的方法可为含有一系列溶解有机物浓度（例如沉积物孔隙水或沉积物/水混合物）的水性样品提供准确且可重复的结果，并且与传统分析方法相比具有实际优势，例如减少样品体积要求、减少溶剂消耗和更少的样品操作，