Determination of phenprocoumon, an anticoagulant, in human plasma.

Phenprocoumon is extracted from acidified plasma, the organic phase evaporated, and part of the residue, in ethanol, is quantitatively applied to a thin-layer plate. After separation, the quantity of phenprocoumon is assayed by fluorescence densitometry in situ. Results are reproducible to about 2.5%. The lower limit of detection is 0.1 mg/liter, which makes the method fully applicable to human plasma, because therapeutic concentrations range from 1 to 3 mg/liter. Seven determinations can be made within 3 h. For toxicological purposes, a qualitative analysis can be done in a shorter time, because the phenprocoumon spots are visible under ultraviolet light at 254 nm.