9.15 : Sample Preparation for Analysis: Advanced Techniques

Sample preparation methods for inorganic analysis depend on the material's properties.

Many inorganic materials that are insoluble in water can be solubilized using strong mineral acids. If they are still undissolved, a more intensive method, known as the fusion technique, is used.

Here, the sample is weighed out and mixed with a flux material in a ratio of about 1 to 10 or 20. The sample-flux mixture is heated in a platinum crucible to obtain a molten mixture. On cooling, this solidifies to yield a new material soluble in water or dilute acid.

In contrast, organic materials are decomposed by dry ashing and wet digestion methods. In dry ashing, the sample is heated in a muffle furnace with atmospheric oxygen. Here, the combustion of the organic material generates an inorganic residue for further analysis.

Wet digestion uses a mixture of acids to break down the organic material.