硫酸-偏钒酸铵-氢溴酸-抗坏血酸体系锡的极谱吸附波研究及其在矿石中的应用

以硫酸-偏钒酸铵-氢溴酸-抗坏血酸为底液,研究了锡的极谱吸附波,并将其应用于矿石中锡的测定。将所选实验方法与使用硫酸-氯化铵-抗坏血酸和硫酸-偏钒酸铵-高氯酸-氯化钾-抗坏血酸为底液测定锡的方法进行对比,结果表明,使用硫酸-偏钒酸铵溶液-氢溴酸-抗坏血酸溶液为底液的极谱法,其灵敏度高于使用硫酸-氯化铵-抗坏血酸和硫酸-偏钒酸铵-高氯酸-氯化钾-抗坏血酸为底液的极谱法。进行了硫酸、偏钒酸铵溶液、氢溴酸及抗坏血酸溶液用量的优化试验,在3 mL硫酸(1+2)、3 mL 0.15 mol/L偏钒酸铵溶液、1 mL氢溴酸、1 mL 100 g/L抗坏血酸溶液体系下峰电流最大,灵敏度最高。在选定的底液条件下能稳定至少24 h。干扰试验结果表明:大量的K⁺、Na⁺,1 mg/mL的Mn、Ca²⁺、Mg²⁺、Al³⁺,100 μg/mL Cu²⁺、Fe³⁺、Zn²⁺,30 μg/mL As,5 μg/mL Si、Cd²⁺、Ga,2 μg/mL Cr、Bi、Sb、Ti,1 μg/mL W、Mo、Hg²⁺对质量浓度小于1.0 μg/mL锡的测定不干扰。方法中锡的检出限为1 μg/mL。方法适用于矿石中0.000 1%～1%锡的测定。方法用于钨矿、钼矿以及铜矿标准物质中锡的测定,测定值与认定值相一致,相对标准偏差(RSD,n=6)为3.7%～8.7%。

Study on the polarographic absorptive wave of tin with sulphuric acid-ammonium metavanadate-hydrobromic acid-ascorbic acid system and its application in ore

With sulfuric acid-ammonium metavanadate-hydrobromic acid-ascorbic acid as base solution, the polarographic absorptive wave of tin was investigated, and it was applied to determination of tin in ore. The selected method was compared with those method using sulfuric acid-ammonium chloride-ascorbic acid system and sulfuric acid-ammonium metavanadate-perchloric acid-potassium chloride-ascorbic acid system as base solution. The results indicated that the determination sensitivity of polarography with sulfuric acid-ammonium metavanadate-hydrobromic acid-ascorbic acid as base solution was both higher than those with sulfuric acid-ammonium chloride-ascorbic acid system and sulfuric acid-ammonium metavanadate-perchloric acid-potassium chloride-ascorbic acid ystem as base solution. The dosage of sulfuric acid, ammonium metavanadate solution, hydrobromic acid and ascorbic acid solution was optimized. The system exhibited highest current and sensitivity when 3 mL of sulfuric acid(1+2), 3 mL of 0.15 mol/L ammonium metavanadate solution, 1 mL of hydrobromic acid and 1 mL of 100 g/L ascorbic acid solution were used. The system could be stable at least 24 h under the selected base solution conditions. The interference test results showed that the determination of tin with mass concentration less than 1.0 μg/mL was not interfered by the following ions: much K⁺ and Na⁺; 1 mg/mL of Mn, Ca²⁺, Mg²⁺ and Al³⁺; 100 μg/mL of Cu²⁺, Fe³⁺ and Zn²⁺; 30 μg/mL of As; 5 μg/mL of Si, Cd²⁺ and Ga; 2 μg/mL of Cr, Bi, Sb and Ti ; 1 μg/mL of W, Mo  and Hg²⁺. The detection limit of method was 1 μg/g. The proposed method was suitable for determination of tin in ore with mass fraction of 0.000 1%-1%. The content of tin in certified reference materials of tungsten ore, molybdenum ore and copper ore was determined by the experimental method. The results were consistent with the certified values. The relative standard deviations (RSD, n=6) were between 3.7% and 8.7%.