光度测定砷的方法常用的有:砷钼蓝法、砷钼黄法、二乙基二硫代氨基甲酸银法(AgDDTC法)等。这些方法多需采取加热还原、有机溶剂萃取等步骤,操作复杂,灵敏度低,ε一般在10~4左右。近年来所研究的一些借助有机溶剂萃取碱性染料-络阴离子缔合物的方法,灵敏度很高,ε普遍大于10~5,满足了某些痕量元素测定的需要。曾先用乙醚浮选分离砷钼杂多酸-罗丹明B缔合物,然后再在乙醚-丙酮溶液中加以测定;继而,他又用环己酮-甲苯混合溶剂选择性萃取结晶紫-砷钼杂多酸的方法光度测砷,ε达3.2×10~5。但方法繁杂,操作条件严苛,重现性差,在实际工作中较难 Spectrophotometric determination of arsenic commonly used methods are: arsenic molybdenum blue method, arsenic molybdenum yellow method, silver diethyldithiocarbamate method (AgDDTC method) and so on. These methods need to take more heat reduction, organic solvent extraction steps, complex operation, low sensitivity, ε is generally about 10 to 4. In recent years, some studies using organic solvent extraction of basic dye - complex anion complex method, high sensitivity, ε is generally greater than 10 to 5, to meet the needs of certain trace elements. Hetero-arsenic heteropolyanadate-rhodamine B complex was first separated by ether flotation and then measured in ether-acetone solution. Then, he was further extracted with cyclohexanone-toluene mixed solvent to selectively extract crystal violet-arsenic Molybdate heteropoly acid method photometry arsenic, ε up to 3.2 × 10 ~ 5. However, complicated methods, severe operating conditions, poor reproducibility, the actual work more difficult