微分펄스 폴라로그라피법에 依한 구리-팔라듐 混合物中의 팔라듐(Pd) 分析方法

Abstract

과량의 구리와 소량의 팔라듐(Pd)이 공존하는 용액에서 Pd만을 선택적으로 분석할 수 있는 폴라로그라피법을 개발하였다. 암모니아-염화암모늄 지지전해질에서 이들 두 성분은 약 0.2V정도 ?龜?된 위치에서 각각 가역적인 환원파를 보이므로 이들 성분의 농도가 비슷할 때에는 동시 정량분석이 가능하다. 그러나 Cu의 농도가 Pd보다 수백배정도로 과량존재할 때에는 앞에 나타나는 Cu피크에 Pd의 것이 중첩되므로 Pd의 분석은 곤란하게된다. 이에 본 연구에서는 Cu와 Pd의 반파전위 순서를 바꾸기 위하여 8 hydroxyquinoline(8-HQ)을 이들이 섞인 혼합용액에 첨가시켰다. 암모니아-염화암모늄(5M) 지지전해질에서 Cu는 8-HQ와 황록색의 결정성침전을 형성하였다. 이 침전을 제거시키기 않고 Pd-8HQ작물의 폴라로그람을 조사한 결과 Pd(NH₃)착물의 환원전위보다 약 0.25V정도 음의 위치(-1.03V vs SCE)에서 Pd의 환원파를 보였으며, 과량의 8-HQ농도하에서 Pd(Ⅱ)농도에 비례하는 확산전류를 얻을 수 있었다.

이 방법으로 1.25M의 Cu(Ⅱ)에 소량의 Pd(Ⅱ)가 녹아있는 혼합용액중의 Pd(Ⅱ)를 분석해보니 약4mM 정도였다. 또한 5회 실험했을 때에 표준편차는 0.054로서 일상분석에는 비교적 신속하고 정확한 방법이라고 생각된다.

A polarographic determination method has been developed for the Palladium in the mixture of a large amount of copper and small Pd. Simultaneouse determination of both components in a similar concentration level would be possible in ammonia-ammonium chloride supporting electrolyte. In the presence of a few hundred times higher copper concentration than the one of palladium, the determination of palladium would be unable to carry out due to the overlaping of copper peak on the Pd one. 8 hydroxyquinoline(8-HQ)(oxine) has been added to the mixture of Cu(Ⅱ) and Pd(Ⅱ) in order to change the order of their half-wave potentials. Fortunately, copper(Ⅱ) was completely precipitated with 8-HQ as a greenish yellow crystalline precipitate in ammonia buffer(5M) solution. The half-wave potential of Pd(Ⅱ)-8HQ complex in the presence of Cu-8HQ precipitate was -1.03V vs SCE shifted 0.25V more negative direction than its amine complex, Pd(NH₃)?. The diffusion current of the Pd complex was proportional to Pd(Ⅱ) concentration in ppm range. A good result was obtained for Pd(4mM) in a mixture containing large amount of Cu(Ⅱ)(1.25M) and small palladium. The method which has been shown the standard deviation of 0.054 for five determinations seems to be relatively rapid and accurate one. Therefore, it could be easily applicable to a routine analysis of palladium in the presence of large amount of copper.

A polarographic determination method has been developed for the Palladium in the mixture of a large amount of copper and small Pd. Simultaneouse determination of both components in a similar concentration level would be possible in ammonia-ammonium chloride supporting electrolyte. In the presence of a few hundred times higher copper concentration than the one of palladium, the determination of palladium would be unable to carry out due to the overlaping of copper peak on the Pd one. 8 hydroxyquinoline(8-HQ)(oxine) has been added to the mixture of Cu(Ⅱ) and Pd(Ⅱ) in order to change the order of their half-wave potentials. Fortunately, copper(Ⅱ) was completely precipitated with 8-HQ as a greenish yellow crystalline precipitate in ammonia buffer(5M) solution. The half-wave potential of Pd(Ⅱ)-8HQ complex in the presence of Cu-8HQ precipitate was -1.03V vs SCE shifted 0.25V more negative direction than its amine complex, Pd(NH₃)?. The diffusion current of the Pd complex was proportional to Pd(Ⅱ) concentration in ppm range. A good result was obtained for Pd(4mM) in a mixture containing large amount of Cu(Ⅱ)(1.25M) and small palladium. The method which has been shown the standard deviation of 0.054 for five determinations seems to be relatively rapid and accurate one. Therefore, it could be easily applicable to a routine analysis of palladium in the presence of large amount of copper.