摘要
合成了苯异硫脲基乙酸（简称ＰＴＨＡ），首次研究了ＰＴＨＡ用于Ｐｄ（Ⅱ）的萃取分光光度性能，实验表明在较高盐酸酸度（３～５ｍｏｌ／Ｌ）下，ＰＴＨＡ与钯形成黄色络合物，能被乙酸丁酯、二氯乙烷萃取，络合物在有机相的最大吸收波长为３６８ｎｍ，摩尔吸光系数ε＝１．３×１０４Ｌ·ｍｏｌ－１·ｃｍ－１，钯含量在０～３０μｇ范围符合比尔定律，可应用于萃取光度法测定钯。研究了萃取光度法的最佳条件，包括酸度、试剂用量、反应速度、萃取时间与有色络合物的稳定性、以及其它离子对测定钯的干扰。同时用电子吸收光谱、平衡移动法测定了钯与ＰＴＨＡ形成的络合物的组成，用紫外光谱、红外光谱探讨ＰＴＨＡ与Ｐｄ（Ⅱ）的配位机理。提出高选择性、简单快速测定钯的新方法。
Phenylthiohydantoic acid(PTHA) was prepared and the structure was
determined by means of NMR and IR. The spectrophotometric determination of palladium by
sovlent extraction was studied. Experiments showed that PTHA and Pd(Ⅱ) form a yellow
complex, which can be extracted from 3～ 5mol/L hydrochloric acid into n butyl acetate or 1,
2 dichloroethane. The optimum conditions for spectrophotometric determination of palladium
with PTHA have been studied.The maximum absorption of the complex is at 368nm and its
apparent molar absorptivity is 1.3×10 4L·mol -1 · cm -1 . Beer's law is obeyed in the
range of 0～30μg/10mL for palladium. Common metal ions do not interfere, a quantity of
noble metal ions also does not interfere except Au(Ⅲ).The method has good selectivity and has
been applied to the determination of palladium in synthesized ore samples with satisfactory
results. The composition ratio of Pd(Ⅱ) to PTHA in the complex has been determined as Pd∶
PTHA=1∶4 or 1∶2 (when PTHA was not enough). The infrared spectra of PTHA itself and
palladium complex showed that PTHA coordinated to palladium through the sulphur atom.
The absorbance ( A ) is larger in hydrochloric acid medium than in sulfuric acid and nitric acid,
but the absorption spectra of the complexes are the same. In sulfuric acid medium, the higher
the concentration of Cl - , the greater the absorbance(A) is. It is suggested that Cl - takes
part in the extracted complex and the composition may be [Pd(PTHA) 4]Cl 2.
出处
《分析试验室》
CAS
CSCD
1999年第2期5-10,共6页
Chinese Journal of Analysis Laboratory
关键词
苯异硫脲基乙酸
钯
萃取分光光度法
测定
Spectrophotometric determination by sovlent extraction
phenylthiohydantoic acid
palladium
