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 mu = 0.55 M, is found to be 10(5.3). The molar absorptivity at 355 nm is 3.16 x 10(4) l mol(-1) cm(-1) at pH 6.3. Beer's law is obeyed up to 20 mumol l(-1) obidoxime chloride concentration. The detection limit of the method is 0.36 mug 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.