Abstract
A systematic study that compares the recoveries of selected organophosphorus pesticides from spiked deionized water using octyl and octadecyl bonded silica sorbents (solid phase extraction, SPE) is reported. A packed column GC is converted to accept a dual wide-bore capillary configuration with chemically dissimilar liquid phases. One column leads to a thermionic detector while the other column leads to a flame photometric detector. The experimental design affords replicate injections and replicate extraction recovery data. Relative standard deviations are calculated that take into account propagation of error for i replicate injections on each of g SPEs performed. The polarity of the dialkyl phosphate ester moiety is correlated with the SPE extraction efficiency.