Comparison of quantitative high performance thin layer chromatography and the high performance liquid chromatography of parabens.

A method is described for the densitometric determination of the p-hydroxybenzoic esters and p-hydroxybenzoic acid in mixtures or in drugs. This method is compared with the one used in high performance liquid chromatography (HPLC). The calibration curves were linear in interval 0.250-3.60 mumol ml-1 per 200 nl per spot. The limit of detection and the relative standard deviation (RSD) are higher than in HPLC (RSD is 6% in HPTLC. 3% in HPLC; limit of detection about 40 pmol in HPTLC and 25 pmol in HPLC) but HPTLC quantitative determination of parabens in drugs is faster.