Which sample preparation step involves the decomposition of organic matter?

• A. Fusion reaction
• B. Liquid extraction
• C. Ashing
• D. Homogenization

Answer: (C)

Decomposition of organic matter in sample preparation is achieved by burning away the organics, turning them into carbon dioxide and water while leaving the inorganic mineral residue behind. This step, known as ashing, makes the inorganic components easier to analyze and reduces interference from the organic matrix. The other techniques have different roles: fusion using a flux dissolves the entire sample for analysis, not specifically removing organics; liquid extraction separates components based on solubility; and homogenization simply mixes or grinds the sample to create uniformity. So the process that decomposes organic matter is ashing.