ALTERNATIVES TO METHANOL WATER ELUTION OF SOLID-PHASE EXTRACTION COLUMNS FOR THE FRACTIONATION OF HIGH LOG KOW ORGANIC-COMPOUNDS IN AQUEOUS ENVIRONMENTAL-SAMPLES

A toxicity-directed method for fractionating non-polar organic toxicants using solid-phase extraction (SPE) is described in phase II of EPA's ''Methods for aquatic toxicity identification evaluations''. This method has been used very successfully to extract and fractionate acutely and chronically toxic complex effluents and ambient waters. However, when fractionating samples that contain very hydrophobic (high log K(ow)) toxicants the methanol-water elution sequence requires modification for optimum results. An elution modification has been made to the phase Il SPE fractionation method for use with aqueous samples which contain such compounds (e.g. sediment pore water). The modified elution and fractionation method has been found to be effective for the separation and isolation of a mixture of compounds with log K(ow) values ranging from 2.5 to 7 from aqueous solution and for toxicants from a sediment pore water sample.