Enantioanalysis of glyceric acid using enantioselective, potentiometric membrane electrodes: applications for the diagnosis of PH II and d-glyceric acidemia/acidurias

d- and l-glyceric acids are human metabolites responsible for two different diseases. Excess excretion of d-GA causes d-glyceric academia/acidurias, while excess excretion of l-GA causes hyperoxaluria type 2, PH II. Enantioselective, potentiometric membrane electrodes (EPMEs) based on maltodextrins I (dextrose equivalence (DE) 4.0-7.0), II (DE 13.0-17.0) and III (DE 16.5-19.5) as chiral selectors are proposed for the determination of l-glyceric (EPMEs based on maltodextrins I and III) and d-glyceric (EPME based on maltodextrin II) acid (l- and d-GA). EPMEs based on maltodextrins I and III can be reliably used for the analyses of l-GA using direct potentiometric method, in the concentration range of 10−8 to 10−6 and 10−6 to 10−3 mol/L, respectively, with very low detection limits (1.19 × 10−9 and 1.0 × 10−7 mol/L, respectively). The EPME based on maltodextrin II was successfully used for the enantioanalysis of d-GA in the 10−5 to 10−3 mol/L concentration range with detection limit of 1 × 10−6 mol/L. The enantioselectivity of EPMEs was determined over l-glyceric acid (or d-glyceric acid), and their selectivity over creatine, creatinine and some inorganic cations such as Na+, K+ and Ca2+. Simply polishing to obtain a fresh surface ready to be used in a new measurement can regenerate the surface of the electrodes.