Indirect Determination of Sulfate and Phosphate in Ternary Materials Using Microwave Digestion ICP–OES and Spectral Line Selection

Trace impurity elements such as sulfur and phosphorus, along with impurity ions like sulfate and phosphate, have a significant impact on the performance of electrode materials. However, the presence of major elements, including nickel, cobalt, and manganese in ternary materials complicates the determination of these trace components. This study establishes an inductively coupled plasma–optical emission spectrometry (ICP–OES) analytical method for detecting sulfur and phosphorus in ternary materials, as well as indirectly determining the content of sulfate and phosphate through formula conversion. The research investigates the optimization of the microwave digestion acid system and evaluates the interference caused by high concentrations of coexisting elements, such as nickel, cobalt, and manganese, on the determination of phosphorus and sulfur spectral lines. A t-test comparison with ion chromatography revealed no statistically significant difference between the two analytical methods. The results demonstrate that the ICP–OES method provides high precision and accuracy, effectively addressing the challenge of determining sulfur, phosphorus, or sulfate, and phosphate content in ternary materials.