Spectrophotometric determination of obidoxime chloride as its Pd(II) complex in water and injections

It has been established that obidoxime chloride reacts with palladium(II) chloride in the pH range 3.9–8.0 and forms a yellow water-soluble (1:1) complex with maximum absorbance at 355 nm. By applying the methods of Sommer, Nash and Job involving non-equimolar solutions the conditional stability constant of the complex, at the optimum pH of 6.3 and an ionic strength μ = 0.55 M, is found to be 10 5.3. The molar absorptivity at 355 nm is 3.16 × 10 4 l mol −1 cm −1 at pH 6.3. Beer's law is obeyed up to 20 μmol l −1 obidoxime chloride concentration. The detection limit of the method is 0.36 μg ml −1. The relative standard deviation ( n = 10) varies over the range 1.10–2.66%. The proposed method was found to be suitable for the accurate and sensitive analysis of obidoxime chloride in water and injection solutions.