[TLC-method for quantitative densitometric determination of piprozoline and its main metabolite using internal standards (author's transl)].

A determination method is described for ethyl (Z-3-ethyl-4-oxo-5-piperidino-thiazolidin-2-ylidene)acetate (piprozoline, Gö 919, Probilin) and its main metabolite (Gö 3284) extracted from the sample to be analyzed at different pH-values, after the addition of two internal standards to the sample. The extracts are then recombined and applied to TLC plates. After developing twice in a cyclohexane/isopropanol mixture, the substances are determined densitometrically on the plates at 275 nm. By comparing the peak area ratios (substance/internal standard) the peaks were quantitated after plotting a calibration curve. The lower sensitivity limit was approx. 100 ng after extraction of a 1 ml sample.