取代三联吡啶光度法测定钴(Ⅱ)

Spectrophotometric Determination of Cobalt(Ⅱ) with Substituted Terpyridine

研究了新显色剂 6 ,6″ 二甲基 4′ 苯基 2 ,2′ :6′ ,2″ 三联吡啶 (TPY)与Co(Ⅱ )的显色反应。结果表明 ,在pH 3 0的NaAc HAc缓冲溶液中 ,该试剂与Co(Ⅱ )发生显色反应 ,形成稳定的绿色络合物 ,其λmax=337 6nm ,表观摩尔吸光系数ε=1 0 3× 10 5L·(mol·cm) -1,Co(Ⅱ )浓度在 0～ 15 μg/ 2 5mL范围内符合比尔定律 ,该方法直接用于维生素B12 中微量钴的测定 ,结果满意。

A colour reaction of cobalt (Ⅱ) with 6,6″-dismethyl-4′-pheny1-2,2′∶6′2″-terpyridine(TPY) was studied by spectrophotometry.The results show that the colour reagent reacts with cobalt(Ⅱ),and forms a stable green complex in the medium of HAc_NaAc with pH 2.8～4.0.The maximum absorption wavelength is at 337.6 nm,and the apparent molar absorptivity is 1.03×10~5 L·mol^(-1)·cm^(-1).Beer's law is obeyed in the range of 1～15μg/25mL for Co(Ⅱ).The method has been used for the direct determination of cobalt in VB_(12) and with satisfactory results.