ABSTRACT
Carbon nanosheets load beta-cyclodextrin (β-CD-CNS) as a new modified electrode materials was reported for the electrochemical determination of sulfadiazine(SD). Carbon nanosheets(CNS) were prepared by a new method of ultrasonic electrolysis in which the β-CD was attached on CNS through ultrasonic dispersion method. The β-CD-CNS composite nanomaterials were immobilized onto glassy carbon electrodes with drops of coating method to construct an SD voltammetric sensor. The differential pulse stripping voltammetry (DPSV) was used to characterize the electrocatalytic behavior of the developed sensor. The Effects of some parameters on the response behavior of the sensor such as pH,modification amount,scanning rate,stirring speed,stirring time,deposition potential and time were investigated and optimized. The results indicated that the β-CD-CNS composite nanomaterials had excellent electroactivity for the SD in neutral solution and greatly improved the current response of SD. Under the optimal conditions, the SD had an irreversible characteristic oxidation peak around+0.87 V,and the oxidation peak current ip(μA) had a good linear relationship with the concentration C ( μmol/L) of the SD in concentration range of 0.05 μmol/L-13.5 μmol/L with correlation coefficients of 0.999. The detection limit was 12.2 nmol/L (S/N=3). The sensor was successfully applied for the trace SD determination in water and milk samples and the recoveries from the spiked samples were 80.0%-102% with RSD≤5.2%.
ABSTRACT
<p><b>AIM</b>To develop a method for separating salicylic acid drugs by aqueous and nonaqueous capillary electrophoresis with conductance detector.</p><p><b>METHODS</b>Fused-silica capillary (55 cm x 50 microns ID) was used. The effects of concentration and pH of the running buffer, running voltage and injection time were studied. Salicylic acid (SA), acetylsalicylic acid (ASA) and sulfosalicylic acid (SSA) can be separated in a 10 mmol.L-1 Tris-30 mmol.L-1 H3BO3 buffer (pH 8.0), the separation voltage and injection time were 24 kV and 10 s, respectively. But tailing peaks appeared. In order to improve the separation efficiency and the sensitivity, ethanol was used as nonaqueous solvent.</p><p><b>RESULTS</b>High sensitivity and resolution for SA, ASA and SSA were obtained in ethanol media, and there was excellent linearity between peak area and concentration of the analytes in the concentration range of 0.05-100 mg.L-1, 5.0-250 mg.L-1 and 0.08-100 mg.L-1 for SA, ASA and SSA, respectively. All the correlation coefficients were over 0.995.</p><p><b>CONCLUSION</b>The analysis of SA and ASA in aspirin tablets was tried and good results were obtained in ethanol media. There was higher sensitivity and separation efficiency than in aqueous media.</p>