Application of capillary electrophoresis in quality control of branched-chain amino acid supplements

Abstract

Branched-chain amino acids (BCAAs) including L-valine (Val), L-leucine (Leu) and L-isoleucine (Ile) are essential amino acids, which play an important role in muscle development, and are often added in food for athletes or bodybuilders. This study presents the application of capillary electrophoresis using a contactless conductivity detector (CE-C4 D) combined with the experimental design using the response surface methodology with central composite design (RSM-CCD) to optimize the analytical process of BCAAs in food supplements. The optimum conditions to be determined include the background electrolyte (BGE) as 1.11M citric acid solution added with 2.32% of PEG (m/v), -16.9 kV of applied voltage, and 45 seconds of injection time. Method validation is performed by defining limit of detection (LOD), limit of quantitation (LOQ), linearity (R2 ), trueness, and precision. The procedure was used to analyse four of real samples, which showed a quite good fit between the BCAAs content measured with CE-C4 D and the information provided by the manufacturers.