Fang G, Meng S, Zhang G, Pan J
Department of Chemistry, Shanxi Yanbei Normal Institute, Datong 037000, People's Republic of China.
Talanta. 2001 May 30;54(4):585-9. doi: 10.1016/s0039-9140(00)00677-9.
The synthesis and purification of a new chromogenic reagent dibromo-p-methyl-bromosulfonazo (DBMBSA) are described. A method is proposed for the spectrophotometric determination of lead with DBMBSA. In 0.24 M phosphoric acid medium, which greatly increases the selectivity, lead reacts with DBMBSA to form a 1:2 blue complex, having a sensitive absorption peak at 638 nm. Under the optimal conditions, Beer's law is obeyed over the range from 0 to 1 mug ml(-1) Pb(II) and the apparent molar absorptivity is 8.44x10(4) l mol(-1)cm(-1). The detection limit and the variation coefficient were found to be 2.45 ng ml(-1) and 1.3%, respectively. It is found that, except for Ca(II) and Ba(II), all foreign ions studied do not interfere with determination. The interference caused by Ca(II) and Ba(II) can be easily eliminated by prior extraction with potassium iodide-methylisobutylketone (KI-MIBK). The method has been applied to the determination of lead in foods with satisfactory results.
描述了一种新型显色剂二溴对甲基溴磺酸偶氮苯（DBMBSA）的合成与提纯。提出了一种用DBMBSA分光光度法测定铅的方法。在0.24 M磷酸介质中（该介质大大提高了选择性），铅与DBMBSA反应形成1:2的蓝色络合物，在638 nm处有一个灵敏的吸收峰。在最佳条件下，铅（II）浓度在0至1 μg ml⁻¹范围内符合比尔定律，表观摩尔吸光系数为8.44×10⁴ l mol⁻¹ cm⁻¹。检测限和变异系数分别为2.45 ng ml⁻¹和1.3%。结果发现，除了钙（II）和钡（II）外，所研究的所有外来离子均不干扰测定。钙（II）和钡（II）引起的干扰可以通过先用碘化钾 - 甲基异丁基酮（KI - MIBK）萃取轻松消除。该方法已应用于食品中铅的测定，结果令人满意。
