1984 Volume 33 Issue 9 Pages 496-497
Spectrophotometric determination of ultratrace amount of copper (II) was reported on our previous paper. A highly sensitive spectrophotometric method is proposed for the determination of manganese(II). This method is based on the accelerating effect of manganese(II) ion on the coloration of potassium trithiocarbonate (K2TTC). By this method, ultratrace amount of manganese(II) can be determined. The recommended procedure is as follows: To a sample solution (4 cm3), containing manganese(II) less than 140 ng, was added alkaline solution of pH 12.2 (12 cm3: containing 0.01 w/v % sodium citrate and 1.8 × 10-3 mol dm-3 potassium cyanide). The mixed solution was cooled with ice, and then added a precooled 0.5 w/v% K2TTC solution (4 cm3). The reaction was allowed to continue for 1 h at 40°C in a dark room. The absorbance of solution was measured at 390 nm against the reagent blank. This accelerating effect was facilitated with an increase in temperature, but the reaction product was decomposed rapidly at above 45 °C. Serious interferences from bismuth(III), copper (II), iron(II), iron(III), and nickel(II) ions can be eliminated by the addition of sodium citrate and potassium cyanide. The R.S.D. (n = 5) of determination for the standard reference material (NIES No. 1 Pepper-Bush) was 3.9 %. This method is highly sensitive with the apparent molar absorptivity of 9 × 106 dm3 mol-1 cm-1, and enables the facile determination of manganese (II) at ppb level.
