Determination of sodium benzoate by chiral ligand exchange CE based on its inhibitory activity in d-amino acid oxidase mediated oxidation of d-serine

A novel quantitative approach for the determination of sodium benzoate (SB) was proposed by the kinetic study about its competitive inhibitory efficiency to d-amino acid oxidase (DAAO) activity with a chiral ligand exchange capillary electrophoresis (CE) method, in which the Zn(II)-l-prolinamide complex was chosen as a novel chiral selector. After the optimization of buffer pH and the chiral selector concentration this chiral ligand exchange CE method was employed to determine labeled d,l-Serine with good linearity (r2 ≥ 0.995), efficient recovery (95.6–100.9%) and remarkable reproducibility (RSD ≤ 1.2%). This chiral separation method was further used to observe DAAO activity through the determination of d-Serine concentration variation after being incubated with DAAO and obtain the sigmoidal inhibitory curve of SB to DAAO activity. The ascending part of this inhibitory curve was linearly fitted in a limited range for SB from 2.0 to 200 μM with an appropriate coefficient of determination (R2 = 0.990). The linearity was then validated to be a promising method for the analysis of SB with the standout merits of high selectivity and adjustable detection range. Furthermore, this proposed method was used for the pharmacokinetics study of SB.