Tranexamic acid (TA) is widely used to treat medical hemorrhagic conditions and as a whitening agent in cosmetic products. The aim of this study was to develop a micro-analytical method of determining TA in widely varying sample matrices, including pharmaceuticals, cosmetics, extracts of the stratum corneum, human keratinocyte cells, and human plasma. Using dansyl chloride as the derivatizing reagent in the pretreatment reduced the reaction time to within 4min in combined microwave-assisted reaction. To prevent excess dansyl chloride and sample matrices from damaging the column, 4μL chloroform was used to remove excess derivatizing agent and interference through dispersive liquid-liquid microextraction (DLLME) method. After pretreatment, 1μL of sample solution was injected in capillary liquid chromatography coupled with ultraviolet detector (CapLC-UV). By coupling the proposed method with cylinder-sampling method, TA was successfully extracted from the stratum corneum. The calibration curves for the standard solution and human plasma were in the ranges of 0.1-50μM and 5-500μM, respectively. Both calibration curves had correlation coefficients (r(2)) of 0.999. The limits of detection were 0.03pmol in standard solution and 3pmol in plasma. Compared to non-derivatized TA, the use of CapLC-UV for detecting derivatized TA provides a 1000-fold sensitivity improvement.
Keywords: Capillary liquid chromatography; Cylinder-sampling method; Derivatization; Tranexamic acid.
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