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研究了铬(VI)-二苯偶氮羰酰肼(DPCO)-聚乙二醇(PEG)体系的萃取行为和显色条件。在pH值为2.0的盐酸-氯化钾缓冲溶液中,络合物中的铬(VI)可被PEG相全部萃取,在PEG相中络合物的最大吸收峰位于550nm处,铬(VI)含量在0~25μg/10mL范围内符合比尔定律,表观摩尔吸收系数ε550=3.13×104L·mol-1·cm-1。人工合成样品中铬(VI)的平均回收率为96.84%。采用该方法测定了辽河原油和沙特原油中的铬(VI),其相对标准偏差分别为2.7%和2.8%,平均回收率分别为99.17%和96.64%。实验证明,该方法具有操作简便、分析速度快、精密度好的优点,是集萃取和显色为一体的测定原油中铬(VI)的较好方法。
The extraction behavior and color development conditions of chromium (VI) -diphenylcarbazone (DPCO) -polyethylene glycol (PEG) system were studied. Chromium (VI) in the complex can be fully extracted by the PEG phase in the hydrochloric acid-potassium chloride buffer solution at pH 2.0. The maximum absorption peak of the complex in the PEG phase is at 550 nm. The chromium (VI) The Beer’s law was obeyed in the range of 0 ~ 25μg / 10mL. The apparent molar absorptivity ε550 = 3.13 × 104L · mol-1 · cm-1. The average recovery of chromium (VI) in synthetic samples was 96.84%. The method was used to determine chromium (VI) in Liaohe crude oil and Saudi crude oil. The relative standard deviations were 2.7% and 2.8%, respectively. The average recoveries were 99.17% and 96.64% respectively. Experiments show that the method has the advantages of simple operation, fast analysis and good precision. It is a better method to determine chromium (VI) in crude oil by combining extraction and color development.