Simple microsulfonylation method for the liquid chromatography–based determination of essential branched-chain amino acids in commercial supplements

Leucine, isoleucine, and valine are essential branched-chain amino acids (BCAAs) that are linked to several metabolic diseases and play important roles in metabolic processes responsible for muscle growth and repair. BCAA-containing nutritional supplements have anabolic effects and are often used to maintain muscle mass and support energy production. Although chromatographic methods exist for BCAA analysis, leucine and isoleucine are isomers and cannot be separated using standard commercial C18 columns. In this study, we successfully determined BCAAs using a simple microderivatization method with quinoline-8-sulfonyl chloride (30 °C, 30 min), followed by high-performance liquid chromatography. The method has a linear range of 3.00–200.00 μg/mL and a detection limit of 1 μg/mL (2 ng per injection). It also uses very little solvent owing to the microliter-scale analytical procedures, including extraction and derivatization. The technique was further applied to analyze BCAAs in commercial supplements. ● Narrow-bore LC was used to detect derivatized branched-chain amino acids (BCAAs) ● Derivatization was conducted using quinoline-8-sulfonyl chloride & mild conditions ● The microscale sulfonylation was performed at 30 °C/30 min ● The method was used to detect BCAAs in nutritional supplements ● Myoblasts were used to survey the compounds associated with BCAA metabolism