Separation and determination of B vitamins and essential amino acids in health drinks by CE-LIF with simultaneous derivatization.

An efficient and sensitive method for the separation and determination of three essential amino acids and three B vitamins by CE-LIF with a simultaneous derivatization procedure was developed. The conditions for derivatization and separation of these micronutrients were investigated. FITC was used as the reagent for fluorescence tagging of arginine (Arg), valine (Val), tryptophan (Trp), folic acid (FA), and niacinamide (NA). Riboflavin (RF) was detected without derivatization. Derivatization of analytes dissolved in borate solution was performed by successive introduction of fluorescence reagent and analytes followed by water bathing at 43°C. The molar ratio of sample/reagent (S/R), derivatization temperature, and incubation time significantly influenced the efficiency of derivatization. To maximize the fluorescence yield, a high S/R (≥20) was required. The nonderivatized RF and five derivatized analytes were separated in the optimized CE-LIF system with the application of 22 kV voltage and 25 mM borate buffer at pH 9.85. Validation of the method showed good linearity for the corrected peak areas versus standard concentrations for the six analytes. The RSDs (n = 3) of the migration time and the peak area obtained for the analytes ranged from 0.4 to 1.1% and from 1.9 to 4.4%, respectively. The developed method, with the lowest LOD of 0.5 nM, was successfully applied for the efficient derivatization and determination of B vitamins in four health drink samples.