Screening of Organohalogenated Toxicants in Breast Milk via GCxGC/TOF MS

母乳中环境毒物的存在是一个重要的问题，因为这些化学物质对母乳喂养的婴儿有潜在的健康影响。亲脂性毒物主要集中在高脂母乳中，它们包括几种不同类别的合成有机污染物，如多氯联苯(PCBS)、多氯二苯并对二恶英(PCDDs)、多氯二苯并呋喃(PCDFs)、多溴二苯醚(PBDEs)和持久性农药。母乳喂养的婴儿体内这些毒物的负担比成年人高一个数量级以上，成年人体内的毒物水平升高与生殖、行为和中枢神经系统的几种紊乱有关。环境科学家继续努力测量母乳中的有毒物质，这是确定这些化学物质对婴儿健康的真正贡献的一个重要因素。有必要开发新的分析性筛选战略，以监测已知环境污染物的水平，并确定 母乳中含有额外的有毒物质。目前的筛查方法采用耗时的样品提取方案，样品的分析仅限于已知毒物的清单，因此无法检测新的或未知的污染物。本项目旨在开发一种基于搅拌棒吸附萃取(SBSE)和全二维气相色谱/飞行时间质谱仪(GCxGC/TOF MS)相结合的改进方法。 具体目标是：(1)开发基于搅拌棒吸附萃取(SBSE)技术的高通量样品前处理方法；(2)基于新兴的全二维气相色谱/飞行时间质谱仪(GCxGC/TOF MS)技术开发高效样品分析方法。GCxGC/TOF MS的主要优势是比传统GC方法的分辨率、分析吞吐量和灵敏度都有所提高；以及(3)通过一项试点研究来验证新方法，该研究将测试GCxGC/TOF MS方法与当前最先进的方法相比的总体选择性、灵敏度和分析吞吐量。

The presence of environmental toxicants in human breast milk is an important concern because of the potential health effects of these chemicals to the breast-fed infant. Lipophilic toxicants are preferentially concentrated in high-fat breast milk, and they include several different classes of synthetic organic pollutants such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polybrominated diphenylethers (PBDEs) and persistent pesticides. The body burden of these toxicants in breast-fed infants is more than an order of magnitude higher than it is in adults, and elevated levels in adults have been linked to several disorders of the reproductive, behavioral, and central nervous systems. The continued efforts of environmental scientists to measure toxicants in breast milk are an important factor in the determination of the true contribution of these chemicals to the health of the infant population. There is a need to develop new analytical screening strategies that will monitor the levels of known environmental pollutants as well as identify additional toxicants in breast milk. Current screening methods employ sample extraction protocols that are time-consuming, and the analysis of samples is limited to the list of known toxicants and therefore not capable of detecting new or unknown contaminants. This project is intended to develop an improved method based on the combined emerging technologies of stir bar sorptive extraction (SBSE) and comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GCxGC/TOF MS). The specific aims are to: (1) develop a high-throughput sample preparation protocol based on the stir-bar sorptive extraction (SBSE) technique; (2) develop a high-performance sample analysis protocol based on the emerging technology of comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GCxGC/TOF MS). The key advantages of GCxGC/TOF MS are enhanced resolution power, analytical throughput and sensitivity over conventional GC; and (3) Validate the new method through a pilot study that will test the overall selectivity, sensitivity and analytical throughput of the GCxGC/TOF MS method when compared to the current state-of-the-art.