科研之友
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摘要
A new dispersive liquid-liquid microextraction (DLLME) was developed on the basis of two phenomena, chloroform can be generated by the reaction of chloral hydrate and sodium hydroxide, and the chloroform droplets dispersed into bulk aqueous solution can be swiftly carried to the bottom of the centrifuge tube with the addition of calcium chloride. The advantages of the new DLLME lie in dispersive solvent free and centrifugation operation compared with the conventional DLLME. Three common aromatic amines were chosen as the analytes to verify the feasibility of the new DLLME method. These compounds were analyzed by capillary zone electrophoresis (CZE) with the background electrolyte aqueous solution containing 80 mmol/L H3PO4 + 60 mmol/L Tris (pH = 2.6). Considering the compatibility of the resultant sample solution and separation media in CZE, a back-extraction technique was performed by an acidic electrolyte solution containing potassium ion (80 mmol/L KH2PO4 + 5 mmol/L H3PO4, pH = 2.85) to transfer these aromatic amines from chloroform phase to aqueous phase which was helpful to complete transient isotachophoresis stacking on the capillary. The effects of the amounts of chloral hydrate and sodium hydroxide, the kinds and amounts of inorganic salts added, extraction time and the composition of the back-extraction solution on the peak areas for the three compounds were investigated. Under optimum conditions, it took less than 8 min to complete sample preparation and analytsis for each sample. The LODs for benzidine, N-methylaniline and m-toluidine were 0.20, 1.23 and 1.08 mu g/L, respectively, which were better than those recently reported values with other methods. The average recoveries for three compounds were within 80.7%-110.2% when tap water and rain water were analyzed.
- 出版日期2013-12
- 单位河北大学
