1-[(5-溴-2-吡啶)偶氮]-2-萘酚-6-磺酸分光光度法测定痕钯量的研究

Spectrophotometric Determination of Trace Palladium With 1-(5-Bromo-2-pyridvlazo)-2-naphthol-6-sulfonic Acid

本文研究了1-[(5-溴-2-吡啶)偶氮]-2-萘酚-6-磺酸(以下简称5-Br-PAN-S)与Pd^(2+)络合物的光度特性和显色反应的最佳条件。在pH 5,试剂与钯形成1:1的络合物,稳定常数K 1.1×10~3λ_(max)620nm,表观摩尔吸光系数ε_(620)=1.08×10~4L·mol^(-1)·cm^(-1),Pd^(2+)浓度在0～35μg/25ml范围内遵守比耳定律。本法可满意地用于钯催化剂中微量钯的测定。

The reaction of1-(5-bromo-2-pyridylazo)-2-naphthol-6-sulfonic acid(5-Br-PAN-S)with palladium(Ⅱ)is studied. At pH 5, the complex formation is slow at room tempeature, however, it can be completed within 3min at 100℃, and the complex is stable for at least 24h. The composition of this complex is palladium(Ⅱ): 5-Br-PAN-S=1: 1. The stability constant of the complex is 1.1×10~8. The apparent molar absorptivity is 1.08×10~4L·mol^(-1)·cm^(-1) at 620nm. Beer's law is obeyed in the range of 0～35μg/25ml for palladium(Ⅱ)with a r of 0.9998. The method has been applied to the determination of trace palladium in palladium catalyst with satisfactory results.