title: Study on sensitivity development of 2,3-dihydroxybenzoic acid by capillary zone electrophoresis-amperometric detection with p-methyl benzoate as stacking agent.
abstract: For its high reactivity and very short half-life, the hydroxyl radical (OH.) in vivo is very difficult to be detected. Usually, it is indirectly quantified by determining 2,3-dihydroxybenzoic acid (2,3-DHBA) and 2,5-dihydroxybenzoic acid (2,5-DHBA), which are the reaction products of salicylic acid (SA) and OH.. Because 2,5-DHBA could be directly formed by the P(450) enzyme, only 2,3-DHBA is regarded as the real biomarker of OH.in biological studies. But the very low concentration of OH* in human bodies makes its determination very difficult and complicated. In this paper, a simple online stacking capillary zone electrophoresis coupled with amperometric detection (CZE-AD) method was explored to improve the detection sensitivity of 2,3-DHBA to reach the requirements in biological analysis. A mixture solution of 12.5 mmol/L Na(2)B(4)O(7)-25 mmol/L NaH(2)PO(4) (pH 7.9) was used as the running buffer and p-methyl benzoate was selected as a suitable stacker. The effects of the concentration, pH value, and injection time of p-methyl benzoate on stacking efficiency were carefully studied. Under the optimum stacking CZE-AD conditions, the detection sensitivity of 2,3-DHBA was improved about 20-fold and its detection limit reached the 10(-9) mol/L level. The experimental results showed that this was a potential method to determine OH* in vivo.
authors.affiliation: Department of Chemistry, East China Normal University, Shanghai, PR China.
authors.forename: Qingjiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Xiang
authors.initials: X
authors.lastname: Chen
authors.forename: Jin
authors.initials: J
authors.lastname: Lu
authors.forename: Pingang
authors.initials: P
authors.lastname: He
authors.forename: Yuzhi
authors.initials: Y
authors.lastname: Fang
mesh_terms: D001565:Benzoates / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods*; D019075:Electrophoresis, Capillary / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D062385:Hydroxybenzoates / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D001565:Benzoates; D062385:Hydroxybenzoates; C009135:2,3-dihydroxybenzoic acid; C009504:4-toluic acid