Generic Enrichment of Organic Contaminants in Human Biomonitoring: Application in Monitoring Early Life Exposures to Fipronil via Breast Milk.

In human biomonitoring, a high-throughput extraction and enrichment method for multiple types of organic contaminants at the part-per-trillion level is critical yet challenging, especially in the limited sample volume. When large-scale sample analysis is involved, low cost is often what we should consider. We describe a generic and straightforward cold-induced liquid-liquid extraction (CI-LLE) strategy to meet this need. Current methods for extracting and enriching organic contaminants from biological samples often require multistep sample processing, including specially tailoring the extraction solvent or adsorbents. This method uses cold-induced phase separation to achieve the extraction and enrichment of studied organic contaminants by adjusting the proportion of acetonitrile/water mixture, so as to integrate the extraction and enrichment in one step without additional reagents and adsorbents. In this study, fipronil insecticide was used as a representative compound to determine the key parameters of CI-LLE. The optimized CI-LLE procedure allowed simultaneous extraction and enrichment of studied organic contaminants, providing excellent enrichment factors (especially for lipophilic organic contaminants). CI-LLE was further applied in monitoring early life exposures of fipronil in 109 breast milk samples. This study provided baseline data on fipronil levels in breast milk samples from China. For infants, exposure to fipronil is of concern. In summary, CI-LLE provides a feasible solution for a generic, efficient, and low-cost preparation of biological samples and promotes high-throughput batch analysis of organic contaminants for large-scale human biomonitoring.