A rapid and simple capillary electrophoresis procedure for quantification of vanillylmandelic acid in urine samples

Aim: To develop a one-step vortex-assisted liquid-liquid extraction (VALLE) method, without the need for evaporation and reconstitution steps, to establish a rapid and straightforward treatment procedure based on capillary electrophoresis-diode array detection (CE-DAD) for the determination of vanillylmandelic acid (VMA) in human urine. Methodology: Optimization of VALLE and CE-DAD procedures were studied in detail. The effects of various experimental parameters, such as the type of the extraction solvent, sample pH, salt addition, and extraction time were investigated. Also, CE separation conditions including background electrolyte type, concentration, and pH, injection time and separation voltage were optimized as well. Results: A successful separation of VMA was achieved in less than 6 min using a basic background electrolyte composed of 60 mmol·L-1 acetate/ACN (acetonitrile) 50% (v/v) (final apparent pH is 5.73). The linear response was obtained over the concentration range from 1.0 to 14 μg·mL-1. The limit of detection and quantification were 0.30 and 1.0 μg·mL-1, respectively. The intra- and inter-day precisions were found to be less than 4.3%. The extraction recoveries of VMA were between 95%-97%. Conclusion: The developed method is found to be a simple, rapid, and reliable method for quantitative analysis of urinary VMA.