engleski

DEVELOPMENT OF HIGH-RESOLUTION MICROFLUIDIC METHOD FOR FAST DETERMINATION OF L-HISTIDINE AND β- ALANINE IN DIETARY SUPPLEMENTS FORMULATIONS

Expanding usage of dietary supplements in today’s modern society arouses the question regarding their safety. International regulations corresponding to their content and safety controls have not been strictly established. Commonly used dietary supplements contain amino acids, thus their safe usage has also been discussed.1 Several risks can be related considering the weak control of this product ; for instance, contamination of dietary supplements, amino acids overdose, or in the adverse case, the consumer can use an ineffective dose. Enacting legislation for regular control of amino acids in dietary supplements would raise a new issue - demand for eluding the common problems associated with the conventionally utilized analytical methods. This report describes the development of new microchip electrophoresis (MCE) method to determine L-histidine and β- alanine in complex dietary supplement formulations. L-histidine and β-alanine containing dietary supplements are used by athletes since they improve endurance during intense exercise. Furthermore, L-histidine is used in dietary supplement formulations to enhance the immune system. For quantification of L-histidine and β- alanine, this study employed a contactless conductivity detector (C4D). The effect of various parameters was observed, aiming to achieve an appropriate detector response and optimal electrophoretic conditions. Established parameters were applied during the analysis of three different dietary supplement samples. All three samples contained one amino acid and some secondary active ingredient. Sample ingredients were wholly separated, and the calculated resolution was high without exception. The measured value of amino acids was agreed with the labeled content. The separation was rapid ; migration time for L-histidine was 38 (±0.2) s, and for β-alanine was 26 (±1) s. Detector response to both analytes showed high linearity in the tested range of 10 - 100 µmol L-1. Detection limits were below 1 mg / L. The analytical characteristics of the proposed microfluidic method showed great potential for further analysis of amino acids in these types of samples. Furthermore, the method is simple, fast, and cost- effective. It belongs to green analytical chemistry since negligible amounts of sample and reagent are required.

β-alanine ; capacitively coupled contactless conductivity detector ; dietary supplements ; L-histidine ; microchip electrophoresis

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