Chambers David M, McElprang David O, Mauldin Joshua P, Hughes Timothy M, Blount Benjamin C
Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia 30341, USA.
Anal Chem. 2005 May 1;77(9):2912-9. doi: 10.1021/ac048456c.
Widespread use of the gasoline additive methyl tert-butyl ether (MTBE) and the subsequent human exposure that follows have led to the need to quantify MTBE in a variety of complex biological matrixes. In this work, we demonstrate our latest MTBE quantification assay for whole blood and uncover previously unidentified contamination sources that prevented routine quantification in the low picogram per milliliter (parts per trillion, ppt) range despite a sensitive and selective analytical approach. The most significant and unexpected sources of contamination were found in reagents and laboratory materials most relevant to sample preparation and quantification. In particular, significant levels of MTBE were identified in sample vial septa that use poly(dimethylsiloxane) (PDMS)-based polymers synthesized with peroxide curing agents having tert-butyl side groups. We propose that MTBE is one of the byproducts of these curing agents, which cross-link PDMS via the methyl side groups. Residual MTBE levels of approximately 20 microg/septa are seen in septa whose formulations use these curing agents. Fortunately, these levels can be significantly reduced (i.e., <0.2 ng/septa) by additional processing. Performance achieved with this sample preparation approach is demonstrated using a mass spectrometry-based method to quantify blood MTBE levels in the low-ppt range.
汽油添加剂甲基叔丁基醚（MTBE）的广泛使用以及随之而来的人体接触，使得有必要对各种复杂生物基质中的MTBE进行定量分析。在这项工作中，我们展示了针对全血的最新MTBE定量分析方法，并发现了以前未识别的污染源，尽管采用了灵敏且具选择性的分析方法，但这些污染源仍阻碍了在低皮克每毫升（万亿分之一，ppt）范围内的常规定量分析。最主要且出乎意料的污染源存在于与样品制备和定量分析最相关的试剂和实验室材料中。特别是，在使用基于聚二甲基硅氧烷（PDMS）的聚合物制成的样品瓶隔垫中发现了大量MTBE，这些聚合物是用过氧化物固化剂合成的，固化剂带有叔丁基侧基。我们认为MTBE是这些固化剂的副产物之一，它们通过甲基侧基使PDMS交联。在使用这些固化剂配方的隔垫中，可观察到残留MTBE水平约为20微克/隔垫。幸运的是，通过额外处理，这些水平可显著降低（即<0.2纳克/隔垫）。使用基于质谱的方法对低ppt范围内的血液MTBE水平进行定量分析，展示了这种样品制备方法所实现的性能。
