Determination of tranexamic acid in various matrices using microwave-assisted derivatization followed by dispersive liquid–liquid microextraction

• A unique sample preparation was performed by derivatizing TA through MAD with DNS-Cl.
• Only 4 μL CHCl3 was used in DLLME method to reduce and eliminate interferences in sample matrices.
• The developed method can be used to detect TA in pharmaceuticals, cosmetics and biosamples.
• Cylinder-sampling method can be used to extract TA from human stratum corneum.

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 4 min in combined microwave-assisted reaction. To prevent excess dansyl chloride and sample matrices from damaging the column, 4 μL chloroform was used to remove excess derivatizing agent and interference through dispersive liquid–liquid microextraction (DLLME) method. After pretreatment, 1 μL 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 0.1–50 μM and 5–500 μM, respectively. Both calibration curves had correlation coefficients (r2) of 0.999. The limits of detection were 0.03 pmol in standard solution and 3 pmol in plasma. Compared to non-derivatized TA, the use of CapLC-UV for detecting derivatized TA provides a 1000-fold sensitivity improvement.