Determination of lead in ore by 2-[(5-bromine-2-pyridine)-azo]-5-diethylaminophenol spectrophotometry with potassium bisulfate precipitation separation
WANG Ji-yan, LIU Mian, YAN Hong-ling, LIAN Wen-li, ZHANG Fan
Henan Rock and Mineral Testing Center, Zhengzhou 450001, China
Abstract:During the determination of lead in ore by 2-[(5-bromine-2-pyridine)-azo]-5-diethylaminophenol (5-Br-PADAP) spectrophotometry, the interference of many elements (such as Cu, Zn, Fe, Ni, Bi, Mn, Cd, Co, V, Ti, Nb and Ta) could not be ignored. To solve this problem, the sample was pretreated by KHSO4 precipitation method. Then, the content of lead in ore was determined by 5-Br-PADAP spectrophotometry. The results showed that the lead in sample could be fully precipitated and separated from ions above by adding 10 mL 200 g/L KHSO4 solution and placing for 20 min after dissolving the ore with hydrochloric acid-nitric acid system. After filtration, the K2SO4·PbSO4 composite salt precipitation was dissolved with HAc-NaAc buffer solution at pH 5.6, realizing the separation from Ba, W, Sr and Ca. Then, 0.4 mL of H3BO3-KCl-NaOH buffer solution at pH 9.3, 0.4 mL of saturated KI solution, 0.4 mL of 10% (V∶V) Trion X-100 solution and 1.0 mL of 0.03 g/L 5-Br-PADAP ethanol solution were added into sample solution successively. The content of lead was determined in 1 cm cuvette at 558 nm. The Beer's law was obeyed for Pb with mass concentration in range of 0.02-2 μg/mL. The correlation coefficient of linear regression equation was 0.998. The detection limit was 0.02 μg/mL. The proposed method was applied to the determination of Pb in certified reference materials of lead ore, zinc ore and lead-zinc ore. The found results were basically consistent with the certified values. The relative standard deviations (RSD, n=11) were between 2.3% and 5.8%.
王冀艳,刘 勉,闫红岭,连文莉,张 帆. 硫酸氢钾沉淀分离—2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚光度法测定矿石中铅[J]. 冶金分析, 2016, 36(4): 71-75.
WANG Ji-yan, LIU Mian, YAN Hong-ling, LIAN Wen-li, ZHANG Fan. Determination of lead in ore by 2-[(5-bromine-2-pyridine)-azo]-5-diethylaminophenol spectrophotometry with potassium bisulfate precipitation separation. , 2016, 36(4): 71-75.
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