5-Br-PADAP显色剂分光光度法测定原油中的铜

Determination of Cu in crude oil by spectrophotometry using 5-Br-PADAP as colour reagent

在非离子表面活性剂TritonX - 10 0存在下,铜(Ⅱ)与5 -Br-PADAP发生反应,生成稳定的紫红色络合物,用分光光度法测定其吸光度,最大吸收波长位于5 5 8nm处,铜含量在0～14 μg 2 5mL范围内服从比尔定律,摩尔吸收系数ε=1.0 2×10 5L·mol- 1 ·cm- 1 ,以六偏磷酸钠和三乙醇胺作为联合掩蔽剂消除了Ni2 + 、Mn2 + 、Fe3+ 、V5+ 、Ti4 + 、Mg2 + 、Al3+ 等干扰离子的影响。人工合成样的回收率在99.2 9%～10 1.0 2 %之间,相对标准偏差≤0 .6 4 %。使用该方法测定辽河原油和沙特渣油中铜的含量,其RSD分别为4 2 %和4 9% ,加标平均回收率分别为10 0 5 9%和98 92 % ,实验结果表明,方法灵敏度、准确度高,选择性好,简便快速,结果令人满意。

In the presence of Tritox X-100, Cu(Ⅱ) reacts with 5-Br-PADAP to form stable purple complex. The maximum absorption wavelength is at 558 nm. Beer's law is obeyed when concentrations of Cu(Ⅱ) are in the range of 0～14 μg/25mL. The molar absorption coefficient is 1.02×105L·mol -1·cm -1· The interferences of Ni 2+, Mn 2+, Fe 3+, V 5+, Ti 4+ and Al 3+ are eliminated by using calgon and triethanolammonium as masking reagents. The recoveries of synthetic samples are between 99.29%～101.02% with RSD less than 0.64%. Cu contents in Liaohe crude oil and Saudi Arabia residuum were determined with this method. The RSDs are 4.2% and 4.9%, and the recoveries are 100.59% and 98.92%, respectively. The method is simple, sensitive, accurate and selective, and the results are satisfactory.