Part 6 of this standard specifies a method for the determination of the amount of water-soluble chloride ions in cobalt oxalate. Determination is carried out using the ion selective electrode method, which is suitable for chloride ion concentration ranging from 0.015% to 0.5%. The method overview involves leaching chloride ions in the sample with water heating, and using the chloride ion selective electrode and the corresponding reference electrode, the electrode potential value is determined by a potentiometer. The electrode potential and the negative logarithm of the chloride ion concentration are linearly related within the measurement range, and the chloride ion amount is calculated by the standard Linear dispersion method. The standard also includes requirements for the required reagents and instruments, such as sodium nitrate solution, chloride ion standard storage solution, and potential measurement instrument.