Meso-四-(3,5-二溴-4-羟基苯)卟啉分光光度法测定虾中铅的含量
Determination of lead in shrimp with meso-tetra (3, 5-dibromo-4-hydroxyphenyl) porphyrine by spectrophotometry
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摘要: 研究了溴代卟啉试剂meso-四-(3,5-二溴-4-羟基苯)卟啉分光光度法测定虾中铅的含量。应用分光光度计测定了meso-四-(3,5-二溴-4-羟基苯)的用量、氢氧化钠及增敏剂的用量、温度、时间等5个因素对生成配合物的影响,确定了反应进行的最佳条件,建立起一种的测定虾中铅含量的方法。在本实验条件下,所得的最佳参数为:0.3mol/L NaOH的用量为0.40mL,沸水浴加热时间为3min。实验测得,生成配合物的最大吸收波长在479nm处,铅含量在0.11.0μg/mL范围内服从比尔定律,标准曲线的回归方程为:y=0.9237+0.0115(R=0.9995),表观摩尔系数为1.528×108L(/mol·cm)。本实验采用传统的干法灰化法消化样品,沉淀法富集铅离子,操作简单,重现性好,用于虾中铅的测定,结果令人满意。Abstract: A spectrophotometric method for the determination of trace lead in foods with meso-tetra (3, 5-dibromo-4-hydroxyphenyl) porphyrine as chromogenic reagent had been studied. The effect of meso-tetra (3, 5-dibromo-4-hydroxyphenyl) porphyrine amount, pH, top, emperature and time on the stability of the formed complex were assayed. An excellent method used to determine the lead in shrimp had been ascertained. The optimal parameter under the experimental conditions was as followed:0.40mL 0.3mol/L NaOH, 100℃ water-bathing for 3min. The soret band of the complex was at 479nm. Beer’s law was obeyed in the range of 0.1~1.0μg/mL of Pb. The regressive equation of standard curve was y=0.9237+0.0115 (R=0.9995) and apparent molar absorptivity was 1.528×108 L/ (mol·cm) . In order to achieve the lead ions enrichment, the samples were treated by traditional cineration and the lead was enriched with method of precipitation. Experimental results indicated that the method was easy to operate and had a good reproducibility. It could be used to determine trace amounts of lead in shrimp. Results were satisfactory.