Capillary and packed column GC determination of propoxyphene and norpropoxyphene in biological specimens: analytical problems and improvements.

Several problems associated with the gas chromatographic determination of DPX and NDPX are discussed and an improved method for their extraction and quantification is described. The method involves two separate extractions, one for DPX with SKF 525A as the internal standard and one for NPDX with dinor-LAAM as the internal standard. The use of two internal standards improved quantitative reproducibility by almost 50%. It was also found that routine DPX and NDPX assays were better determined on packed columns than on capillary columns because the quality of the samples and of the columns was critical. The use of two IS and the double extraction procedure is recommended for general toxicological analyses.