2-(2-ベンゾチアゾリルアゾ)-5-ジメチルアミノ安息香酸によるパラジウム(II)の吸光光度定量

A sensitive and selective method for the spectrophotometric determination of palladium(II) with2-(2-benzothiazolylazo)-5-dimethylaminobenzoic acid (BTAMB) has been studied. BTAMB reacts with palladium(II) in aqueous acetone solution (35 % acetone by volume) to form a blue complex with an absorption peak at 695 nm with e =4.96 × 104 1 mol-1 cm-1. The complex is stable for at least 6 h and its stoichiometric ratio of the complex is 1: 1 (Pd : BTAMB). The calibration graph is linear over the concentration range 035μg of palladium(II) per 20 ml of the aqueous acetone solution in a range of pH 2.06.0. The relative standard deviation for 10 determinations at 30.0 μg palladium(II) level is 0.58 %. Common anions and cations do not interfere. The interferences due to Ag(I), Co(II), Cu(II), Ni(II), Os(VIII), Pt(IV), and V(V) can be masked by sodium citrate, and copper(II) by trisodium nitrilotriacetate. The recommended procedure is as follows : Take 5 ml of sample solution containing up to 35 μg of palladium(II) into a 50 ml beaker, add 1 ml of 1 % sodium citrate and 3 ml of 0.2 M potassium hydrogen phthalate buffer (pH 2.5), and adjust the pH to 2.5 with 10 % sodium hydroxide solution. Transfer the solution into a 20 ml glass stoppered test-tube. Add 0.7 ml of 0.05 % BTAMB and 7 ml of acetone. Dilute it to 20 ml with distilled water. After standing for about 10 min, measure the absorbance at 695 nm against the reagent blank. By this procedure, palladium(II) content in catalyst for the clarifier of car exhaust gas was determined.