Separation and quantification of the urinary enantiomers of 2‐hydroxyglutaric acid by capillary electrophoresis with capacitively coupled contactless conductivity detection: Application to the diagnosis of D‐ and L‐2‐hydroxyglutaric aciduria

Abstract

2‐hydroxyglutaric aciduria is an inherited neurometabolic disorder with two major types: D‐2‐hydroxyglutaric aciduria and L‐2‐hydroxyglutaric aciduria. An easy and fast capillary electrophoresis system combined with a capacitively coupled contactless conductivity detection method was developed for the enantioseparation and determination of D‐ and L‐2‐hydroxyglutaric acid in urine. D‐ and L‐2‐hydroxyglutaric acids were separated using vancomycin as the chiral selector. The optimal separation conditions for enantiomers were achieved by the use of a buffer containing 50 mM 4‐(N‐morpholino) butane sulfonic acid solution (pH 6.5), an electroosmotic flow modifier (0.001% [w/v] polybrene), and 30 mM vancomycin as chiral selector. The analysis time was 6 min under optimal conditions. The optimized and validated method was successfully implemented for quantifying D‐ and L‐2‐hydroxyglutaric aciduria in patients’ urine, without any pretreatment step. The linearity of the method was determined to be in the range of 2–100 mg/L for D‐ and L‐2‐hydroxyglutaric acid in urine. The precision (relative standard deviation%) was obtained at about 7%. For D‐ and L‐2‐hydroxyglutaric acids, the limits of detection were 0.567 and 0.497 mg/L, respectively.