树脂相吸附5-Br-PADAP显色体系分光光度法测定原油中的Co^(2+)

Determination of Trace Co^(2+) with Spectrophotometry after Resin-phase Absorb 5-Br-PADAP Colored System

以2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚(简称5-Br-PADAP)为显色剂,采用树脂相光度法测定原油中的微量钴。络合物最大吸收波长位于600nm处,钴含量在0～0.2mg/L范围内服从比尔定律,表观摩尔吸收系数ε=2.254×105L·mol-1·cm-1,相关系数r=0.9999。以三乙醇胺和硫脲掩蔽Ni2+、Cu2+、Fe3+、V5+、Cr3+、Al3+等以消除干扰离子的影响。人工合成样的回收率在96.89%～97.53%之间,RSD为0.24%。使用该方法测定大庆减渣和扶余原油中微量钴的含量,它们的RSD分别为1.66%和0.94%,加标回收率分别在96.85%～101.01%和95.31%～101.90%范围内。实验结果表明,本方法灵敏度、准确度高,选择性好。

Co^(2+) in crude oil is determined by resin-phase spectrophotometry with colored system of 5-Br-PADAP. The maximum absorption wavelength is 600nm. Beer's law is obeyed when the Co~ 2+ amount is 0 to 0.2mg/L.The apparent molar absorption coefficient is 2.254×105 L/(mol·cm) .The correlation coefficient is 0.9999. Ions of Ni~ 2+、Cu~ 2+、Fe~ 3+、V~ 5+、Cr~ 3+、Al~ 3+are masked by triethanolamine and sulfourea. The recovery of synthetic sample is from 96.89% to 97.53%, and RSD is less than 0.24. Co~ 2+content in Fuyu crude oil and Daqing residual oil are determined by the method, whose RSD is 1.66% and 0.94% respectively. The recovery of added standard is from 96.85% to 101.01% and from 95.31% to 101.90%, respectively. The results show that the method is of high sensitivity, high accuracy and good selectivity.