Simultaneous determination of aminothiols, ascorbic acid and uric acid in biological samples by capillary electrophoresis with electrochemical detection

Abstract

A method based on capillary electrophoresis with electrochemical detection has been employed for the separation and determination of homocysteine, cysteine, reduced glutathione, ascorbic acid and uric acid. Effects of several important factors such as the acidity and concentration of the running buffer, separation voltage, injection time and detection potential were investigated to acquire the optimum conditions. The detection electrode was a 500 microm diameter platinum disk electrode at a working potential of +1.05 V (vs saturated calomel electrode). The five analytes were well separated within 10 min in a 50 cm long fused silica capillary at a separation voltage of 18 kV in a 100 mm phosphate buffer (pH 7.8). The relation between peak current and analyte concentration was linear over about 3 orders of magnitude with the detection limits (S/N = 3) ranging from 0.83 to 2.58 microm. The proposed method was successfully applied to determine cysteine, reduced glutathione, ascorbic acid and uric acid in human whole blood and rat brain tissues with satisfactory assay results and should find a wide range of bioanalytical applications.

Tear analysis of ascorbic acid, uric acid and malondialdehyde with capillary electrophoresis

“…Although MDA is detected but not quantifi ed in tears of healthy individuals, the method might be useful for monitoring high MDA concentrations in pathological situations. The time necessary for complete separation of ascorbic and uric acid (18 min) is longer than the analysis time that has been reported (4-10 min) for CE plasma analysis of ascorbic and uric acid (Cheng et al, 1999;Zinellu et al, 2004Zinellu et al, , 2005Matejckov et al, 2007;Ruiz-Jiménez et al, 2007;Yao et al, 2007). This represents the compromise of migration times in favor of sensitivity; indeed our LLOQ values (0.386 and 3.522 mg/L for uric and ascorbic acid, respectively) are lower than those reported for CE with UV detection [10 and 2.5 mg/L for uric and ascorbic acid in Zinellu et al (2004) and 5 and 2.5 mg/L, respectively, in Zinellu et al (2005)].…”

“…Capillary electrophoresis is an analytical technique of high separation capacity, requiring only a few nanoliters of sample for each analysis. Capillary electrophoresis has been used for the determination of ascorbic and uric acid in plasma and urine samples with ultraviolet or electrochemical detection (Cheng et al, 1999;Zinellu et al, 2004;Zinellu et al, 2005;Matejckov et al, 2007;Ruiz-Jiménez et al, 2007;Yao et al, 2007). Although it is an ideal technique for analysis of low volume bio-logic samples such as tears, it has not been applied to the determination of these low molecular weight antioxidants and MDA in tears.…”

Multi‐parameter detection of diabetes mellitus on multichannel poly(dimethylsiloxane) analytical chips coupled with nanoband microelectrode arrays

“…For example, glucose can be detected using a copper electrode with the detection potential at ca. 0.7 V in NaOH [42], whereas organic acids such as uric acid usually produces response at the platinum electrode with the detection potential at 1.05 V in borate buffers [43]. For this reason, an electrode array with different materials is desired for simultaneous detection of different molecules at the same time.…”

Rapid, sensitive and simultaneous determination of ascorbic and uric acids in human plasma by ion-exclusion HPLC-UV

“…Several methods have been presented by different researchers for the determination of ascorbic and uric acids in biological samples such as: spectrophotometric methods, high performance liquid chromatography (HPLC) with electrochemical (EC) or ultraviolet (UV) detection [16,17], and capillary electrophoresis (CE) coupled with UV [18] or EC [19]. However, only a few studies have described the simultaneous determination of AA and UA.…”