Linking Solid Phase Extraction and Enzyme-Linked Immunosorbent Assay to Measure Chlorpyrifos in Fish Tissue

A method for measuring chlorpyrifos in fish tissue coupling solid phase extraction (SPE) and enzyme‐linked immunosorbent assay (ELISA) is described. Fish tissue was added to a silica gel column and extracted with hexane. The eluant was passed through an SPE column (C‐18) and analyzed using ELISA. The method, which was comparable to an FDA GC/ECD method, gave recoveries from 83.4% to 87.5% for fortified fish samples, a lower limit of detection of 0.01 ppm, a linear range from 0.01 to 0.5 ppm, and correlation coefficients from 0.86 to 0.96. Nineteen contaminated fish samples analyzed using both ELISA and GC/ECD methods gave comparable chlorpyrifos concentrations with a correlation coefficient of 0.78.