Rana Hamza Shakil

"For example, nitric acid is commonly used to dissolve metals, while hydrochloric acid is commonly used to dissolve organic matter".

The reverse is closer to the truth :

"For example, hydrochloric acid is commonly (?) used to dissolve metals, while nitric acid is commonly used to dissolve organic matter".

Acid dissolution of phosphate rock samples and phosphate fertilizers can be done with nitric acid alone. The undissolved residue is probably not relevant to the analysis results. But it depends on what is the purpose of the analysis - the total content of elements or only elements bound in the composition of phosphates. If the former, it is best to treat the residue separated from the solution as a separate sample and bring it into the solution, e.g. by fusion with sodium or lithium carbonates and/or borates.

The detailed measurement procedure depends on the technical type of the ICP-MS spectrometer. If in the sample solution obtained after acid digestion, the concentrations of elements are determined at measurable levels by another measurement technique, namely ICP-AES, especially its axial variant, it is better to use it, because it is easier to obtain accurate measurement results. And the ICP-MS technique is irreplaceable up to ultra-trace amounts.

A detailed recipe for analytical procedures can be obtained from analysts who are strictly active in the analysis of this type of sample and use the ICP-MS technique daily with the use of a spectrometer of the same type and model. But I don't think it's necessary and you can do these analyzes by following the general rules.

ZJ