毛细管区带电泳法测定油田水中的脂肪酸

Indirect UV Detection of Short Chain Carboxylic Acids in Oil Field Water by High Performance Capillary Zone Electrophoresis

采用二硝基本甲酸一十六烷基三甲基溴化脓缓冲体系对油田水中短链脂肪酸进行了分析。应用间接紫外法，使脂肪酸在数分钟之内得以分离检测。研究表明，当缓冲溶液pH值为9.0、电解质浓度为5.0mmol／L、表面活性剂浓度为0.5mmol／L和甲醇含量为5％时可达到最佳的分高效果。

Short chain carboxylic acids are the major aqueous organic species in oil field water. It is considered that they play an important role in the geochemical evolution of second porosty in oil reservoir. In this paper,short chain carboxylic acid anions were analyzed by HP3DCE high performance capillary electrophoresis system (Hewlett-Packard,Germany) with a buffer system of dinitrobenzoic acid-hexadecyltrimethyl ammonium bromide (CTAB). The innuence of buffer pH and the concentrations of electroyte,surfactant and methanol on the seper ation of short chain carboxylic acids have been studied. The results showed that the best separatinn of short chain carboxylic acids could be done with the buffer of 10mmol/L dinitrobenzoic acid, 0. 5mmol/L CTAB and 5% methanol at pH= 9.Separations were performed in a 50cm × 50μm i. d. fused silica capillary (effective length 48, 5cm) at 25℃. A negative Potential of 30kV was used for each experiment. Sample was intreduced into the capillary by pressure at 50kPa for 10s. lndirect UV detection was operated at 254nm and reference wavelength at 380nm for all experiments. Negative peak was changed into Poaitive one by exchanging between detection wave length and reference wavelength. Capillary was rinsed for 10min with 0. 1mol/L whium hydroxide and buffer solution before each run. Chl field water was injected directly after filtered through 0. 45μm membrane. The result was satisfactory.