Determination of tranexamic acid in cosmetic products by high-performance liquid chromatography coupled with barrel plating nickel electrode

Tranexamic acid (TA) is an important reagent in cosmetic skin-whitening formulation and a drug for the inhibition of plasminogen to plasmin in blood. Since there is no chromophore in tranexamic acid molecule to enable direct analysis by UV-visible absorption spectrophotometry, derivatization is thus required by excluding use of UV or fluorescence detection. We report here a relatively simple electrochemical TA detection method by using a barrel plating nickel electrode. Chromatographic separation was performed on a Hamilton PRP-X100 anion-exchange column (150mm x 4.1 mm i.d., 10 mu m particle size) with a (85:15, v/v) mixture of 0.1 mol 1(-1) NaOH and acetonitrile as mobile phase and pumped at a flow rate of 0.9 ml min(-1). By detecting at +0.55 V vs. Ag/AgCl, the calibration plot was linear in the concentration window of 3-1000 ppm with regression coefficient and detection limit (S/N=3) of 0.9993 and 0.13 ppm (0.84 mu mol 1(-1)), respectively. Successive injections (n= 10) of 50 ppm tranexamic acid showed a R.S.D. value of only 0.3% indicating good reproducibility of the proposed system. The method was successfuliy applied to the analysis of the content of tranexamic acid in cosmetic products and proved to be suitable for rapid and reliable quality control. (C) 2008 Elsevier B.V. All rights reserved.