光度法同时测定铂和钯

Simultaneous Determination of Platinum (Ⅳ) and Palladium (Ⅱ) Using Spectrophotometry Method

水溶性试剂N-间甲苯基-N’-(对氨基苯磺酸钠)硫脲(MMPT)在HAc-NaAc缓冲介质和CTMAB(溴化十六烷基三甲胺)存在下,与铂(Ⅳ)和钯(Ⅱ)反应形成绿色和褐色水溶性络合物,其最大吸收波长分别为754.4和304.6nm。符合比尔定律的浓度范围分别为0～32μg.(25mL)-1,0～25μg.25(mL)-1,摩尔吸光系数为ε7P5t4.4=8.6×104L.mol-1.cm-1和ε3P0d4.6=7.4×104L.mol-1.cm-1。在754.4和304.6nm波长测定铂,钯混合液的吸光度,换算出铂、钯的含量。50种共存离子中,仅有Cu2+和Co2+对钯的测定有干扰。该法选择性好,用于合成样品、矿石和催化剂样品中铂、钯含量的测定,其相对标准偏差RSD小于2.0%;回收实验回收率是96%～104%。由于试剂铂、钯形成的络合物都易溶于水、不需予先分离同时测定,操作简便,快速,且环境友好。

The N-（m-methylphenyl）-N＇-（sodium p-aminobenzenesulfonate）-thiourea （MMT） was good reagent of water solu-bility. In the medium of an HAc-NaAc buffer solution and hexadecyltrimethylammonium bromide （CTMAB）, MMPT can react with platinum （Ⅳ） and palladium （ Ⅱ ） to form green and brown soluble complex. The maximum absorbance of the complex was at λ^Ptmax=754. 4nm and ,λ^Ptmax=304.6 Beer＇s law was obeyed with the concentration in the range of 0-32.0μg Pt（Ⅳ）/25 mLand 0-25.0μg Pd（ Ⅱ ）/25 mL for platinum （Ⅳ） and palladium（ Ⅱ ） respectively. The correlated coefficient was r754.4=0. 999 5 for platinum （Ⅳ） ; and r304, 6 = 0. 999 9 for palladium （ Ⅱ ）. Their molar absorption coefficients were ε^Pd304.6=7.4×10^4L·mol^-1·cm^-1 and ε^Pd304.6=7.4×10^4 L·mol^-1·cm^-1 respectively. The contents of platinum （Ⅳ） and palladium （Ⅱ） were converted by determination of the absorbency of mix solution of platinum （Ⅳ） and palladium （ Ⅱ） at 754.4 and 304. 6 nm. Only Cu^2＋ and Co^2＋ interfered with the determination of palladium （ Ⅱ ） among 50 coexistent ions, so the selectivity was good. It can be used for the determination of content of synthesis samples. The relative standard deviation （RSD） was less than 2.0%, and the recovery（%） was in the range of 96 %-104 %. The results are satisfactory. Because the reagent reacts with platinum （Ⅳ） and palladium （ Ⅱ） to form water soluble complex and does not require pre-separation for simultaneous determination of platinum （Ⅳ） and palladium （ Ⅱ ）, the method is easy to operate, rapid and environment-friendly.