Why is digestion performed on a wipe sample before ICP-MS or AAS analysis?

• A. To remove lead entirely
• B. To preserve the sample
• C. To increase sample volume
• D. To convert all metals to a detectable form and release lead from matrix

Answer: (D)

Metals on a wipe sample are often bound within the surrounding matrix—organic material, coatings, salts, or oxide surfaces—so they aren’t readily available for measurement. Digestion breaks down that matrix and dissolves the metals into a liquid form, converting them into detectable ionic species that ICP-MS or AAS can quantify. This step ensures all the lead (and other metals) present are released from the substrate and become part of the solution, which improves recovery, accuracy, and consistency by minimizing matrix effects that can distort the signal. It’s not about removing lead completely or preserving the sample; it’s about solubilizing and mobilizing the lead so the analysis can produce a true concentration in solution.