Motomizu S, Wakimoto T, Tôei K
Department of Chemistry, Faculty of Science, Okayama University, Tsushimanaka, Okayama-shi, Japan.
Talanta. 1984 Apr;31(4):235-40. doi: 10.1016/0039-9140(84)80269-6.
Molybdophosphate, formed between orthophosphate and molybdate in sulphuric acid solution, is extracted into a mixture of toluene and 4-methylpentan-2-one (1:3 v v ) with Malachite Green as counter-ion. A single extraction with equal phase volumes gives an apparent molar absorptivity for phosphate of 2.3 x 10(5) l.mole(-1).cm(-1) at 630 nm; the absorbance of the reagent blank is 0.03. With an organic to aqueous phase-volume ratio of 1:10, the molar absorptivity is 2.5 x 10(5) l.mole(-1).cm(-1) and the absorbance of the reagent blank 0.08. By the proposed method, ng ml levels of phosphorus can be determined, and the detection limit is about 0.1 ng ml . The standard deviation and relative standard deviation for the determination of phosphorus in tap water (4.3 ng ml ) are 0.05 ng ml and 1.1%, respectively. The method can also be applied to the determination of phosphorus in river water and sea-water.
在硫酸溶液中，正磷酸盐与钼酸盐反应生成的磷钼酸盐，以孔雀石绿作为抗衡离子，被萃取到甲苯和4-甲基-2-戊酮的混合液（体积比1:3）中。等体积的两相进行单次萃取时，在630nm波长下，磷的表观摩尔吸光系数为2.3×10⁵ l·mol⁻¹·cm⁻¹；试剂空白的吸光度为0.03。有机相与水相的体积比为1:10时，摩尔吸光系数为2.5×10⁵ l·mol⁻¹·cm⁻¹，试剂空白的吸光度为0.08。采用该方法可测定纳克每毫升级别的磷，检测限约为0.1纳克每毫升。测定自来水中的磷（4.3纳克每毫升）时，标准偏差和相对标准偏差分别为0.05纳克每毫升和1.1%。该方法也可用于河水和海水中磷的测定。
