Comparison of Automated and Manual Methods for Solid Phase Extraction from Endocrine Disrupting Chemicals

Endocrine disrupting chemicals (EDCs) are part of an emerging group of contaminants that have been noted for their presence at low concentrations in surface and ground waters. Due to the analytical challenges posed by low levels of EDCs in drinking water, new techniques for the detection and quantification of estrogenic compounds have been the subject of intense investigation. From the wide variety of EDCs, this research focuses on a selected group due to their endocrine-disrupting potential and their presence in natural water supplies. The set of compounds includes diethylstilbestrol, estriol, estradiol, 17β-ethynylestradiol, and estrone. There are many protocols for measuring organic contaminants at trace levels in water, and most call for some pre-concentration, separation and cleanup. Solid phase extraction (SPE) is one of the most widely used methods for pretreatment of these samples. Because of the slow and laborious nature of most SPE protocols, there is great interest in ways of reducing time and cost in EDC analysis. Several instruments which integrate automated SPE with LC/MS have been proposed for addressing these needs. This research compared one of the accepted manual methods (EPA 1694 Method for Pharmaceuticals and Personal Care Products) with an innovative approach using an automated SPE/LC/MS for trace analysis of EDCs. For this work we have selected the Waters AquaAnalysis System. The comparison shows a decrease in error when using the automated version because of the elimination of sample transfers and possible contaminants entering the samples throughout the extraction steps. A significant decrease in cost was also noted when using the automated extraction due to the decrease in labor hours and in the cost of consumables. Since the automated method requires less raw sample, there is a large reduction in cost for sample collection and shipment even prior to extraction