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Study on sensitivity development of 2,3‐dihydroxybenzoic acid by capillary zone electrophoresis–amperometric detection with p ‐methyl benzoate as stacking agent
Author(s) -
Wang Qingjiang,
Chen Xiang,
Lu Jin,
He Pingang,
Fang Yuzhi
Publication year - 2005
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200500153
Subject(s) - capillary electrophoresis , salicylic acid , chemistry , stacking , detection limit , amperometry , chromatography , in vivo , methyl benzoate , biochemistry , organic chemistry , electrode , electrochemistry , microbiology and biotechnology , biology
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 .