A simple, reliable and reproducible method, based on capillary zone e1ectrOphOresis with amperometric detection (CZE-AD), has been developed for simultaneous determination of four active ingredients in Vc Yinqiao tablets including paracetamol, vitamin C, cafeic acid and chlorogenic acid. A carbon-disk electrode was used as working electrode and 0.95V (versus SeE) was selected as detection potentia1. The optimal conditions of CZE experiment were 30 mmol•L-1 borate solution (pH 9.5) as running buffer, 14 kV as separation voltage and 8s (l4kV) as electro-kinetic sampling time. Under the selected optimum conditions, paracetamol, vitamin C, caffeic acid and chlorogenic acid could be perfectly separated within 22min, and their detection limits (S/N=31 ran ged from 5×l0-7 to 1×l0-6mol•L-1. Th is proposed method demonstrated good reproducibility with relative stan dard deviations of less than 3％ for both migration time and peak current (n＝7). The utility of this method was demonstrated by monitoring a kind of compound medicine named Vc Yinqiao tablets and the assay results were sarisfactory.

Hydroxyl radical (OH•) can cause severe damage to cells and tissues. However, its analysis is very difficult for its high reactivity and very short half-life. In this paper, a simple and highly sensitive method, capillary zone electrophoresis with amperometric detection (CZE-AD) was introduced indirectly to determine OH• by determining its reaction products with salicylic acid (SAL), 2, 3-dihydroxybenzoic acid (2, 3-DHBA) and 2, 5-dihydroxybenzoic acid (2, 5-DHBA). The optimum conditions of CZE-AD for the determination of 2, 3-DHBA and 2, 5-DHBA were explored. Under the optimum conditions, SAL, 2, 3-DHBA and 2, 5-DHBA could be perfectly separated within 15 min, and the linearity ranges of 2, 3-DHBA and 2, 5-DHBA were between 1.0×10−7 and 1.0×10−4 mol l−1. Their detection limits were as low as 2×10−8 mol l−1, which were much lower than that in CE-UV method. The method was also applied to study the free OH• scavenging activity of angelica polysaccharide. The experimental results showed that this CZE-AD method was very sensitive and practical in both the determination of free OH• and the evaluation offree OH• scavenging activities of antioxidants. 2003 Elsevier B. V. All rights reserved.

-5 nA l mol-1, respectively, and their detection limits were 5.0/10-7 and 2.0/10-7 mol l-1, respectively (S/N＝3). Above results demonstrated that this method was of high sensitivity, good repeatability, high selectivity and could be used in metabolic kinetics studies of medicines. Satisfactory results were obtained when this method was used to simultaneously analyze the amounts of RT and HCT in one general compound Chinese herb medicine-Zhen Ju jiang Ya Pian and human urine samples.

In this paper, capillary zone electrophoresis with amperometric detection was firstly applied to indirectly determine the composition of Chinese ligustrum lucidum polysaccharide (LLPS) by analyzing its hydrolyzates: fucose, glucose, arabinose and rhamnose. Under the selected optimum conditions, the four monosaccharides could be perfectly separated within 30 min and showed significant current responses at the copper electrode. The linear ranges of fucose, glucose and arabinose were all from 5.0/10-6 to 1.0/10-4 mol l-1 and that of rhamnose was from 1.0/10-5 to 1.0/10-4 mol l-1, and their detection limits were lower or near 1.0/10-6 mol l-1 (S/N＝3). Experiments showed that the mole ratio of fucose, glucose, arabinose and rhamnose in Chinese LLPS was 1.80:4.58:2.55:1.91, and the purity of this polysaccharide leached by the introduced leaching method was 93.3%. Analyzing polysaccharide by this method has some merits of quickness, low-volume sampling, simple instrument, high sensitivity and high reproducibility. # 2003 Elsevier Science B. V. All rights reserved.

A simple and reproducible method, based on micellar electrokinetic capillary chromatography (MECC) with amperometric detection (AD), for the separation and determination of the biogenic amines and their precursor amino acids was studied in this paper. The optimal conditions of separation and detection of typtamine, tyramine, tryptophan and tyrosine were 0.020 mol l-1borate-NaOH (pH10.35) containing 0.03 mol l-1 sodium dodecylsulphate (SDS) as running buffer, 20kV as separation voltage, and+800mV (vs. SCE) as detection potential. Under the optimum conditions, the four analytes were separated completely within 15 minutes, and good linearity, reproducibility and recovery results were obtained. Based on three times standard deviation of a low level sample, the detection limits for the four analytes were as low as at 10-7 mol l-1 level. This method was also successfully used in the analysis of actual rice spirit, and satisfactory assay results were obtained.

The composldonofhunlnarln was firstly determined by analyzing its hydrolysis monosacchaddes with capillary zone electrophoresis-amperometric detection (CZE-AD). Under the selected optinmm condiUons, hreose, galactose, glucose, mannoae and xylose, which are hydrolysis productsdf laminarin, copld be perfecOy separated within 20min and showed significant current responses at copper electrodes. The linear ranges of fucose, galactose and glucose were from1.0

A simple, reliable and reproducible method, based on capillary zone electrophoresis with amperometric detection (CZE-AD), was developed for simultaneous determination of 3-amino-3-azabicyclo[3, 3, 0]octane (aminoheterocycle) and 3-azabicyclo[3, 3, 0]octane (azabicycle)in gliclazide bulk drug. The optimal conditions of CZE-AD were 50mM borate solution (pH 9.0) as running buffer, 14kV as separation voltage and 0. 95V (versus SCE) as detection potential. Under the selected optimum conditions, the two analytes could be perfectly separated within 9 min. The linearity range of aminoheterocycle was from 1.0×10−6 to 1.0×10−3M and that of azabicycle was from 2.0×10−6 to 1.0×10−3M. Their detection limits were 5.0×10−7 and 1.0×10−6M, respectively, (S/N=3). This proposed method demonstrated long-term stability and reproducibility with relative standard deviations of less than 2% for both migration time and peak current. It has been successively used for the determination of these two analytes in gliclazide bulk drug, and the assay results were satisfactory. 2005 Elsevier B. V. All rights reserved.

The formation of free hydroxyl radical (OH) in oxygen transfer reactions at PbO2 electrodes and the reaction between the electrochemically produced OH and salicylic acid (SA) were studied by cyclic voltammetry and capillary electrophoresis-amperometric detection (CZE-AD) in this paper. Experiments showed that OH was formed in the potential range of 1.0-1.4V corresponding to the anodic discharge of H2O at the PbO2 electrode, while this phenomenon was not obvious at the Pt electrode. Optimum CZE-AD conditions for indirect determination of OH were explored. It was also found that when salicylic acid was used to trap OH produced on the PbO2 electrode surface, the amount of 2, 5-dihydroxybenzoic acid produced is much more than that of 2, 3-dihydroxybenzoic acid. This phenomenon is explained by the proposal that SA first forms an active aromatic radical on the PbO2 electrode surface before trapping OH, where OH performs a stronger preference in attacking at the 5-position than for attacking at the 3-position of the aromatic radical. 2005 Elsevier B. V. All rights reserved.