What process is used to prepare samples for metals analysis?

The process of digestion is essential for preparing samples for metals analysis because it involves breaking down complex matrices in environmental samples, such as water and sludge, to release the metals into a more analyzable form. This typically entails using strong acids or a combination of acids to dissolve the sample, effectively converting solid or particulate forms of metals into their ionic forms. This process ensures that all relevant metals are solubilized and can be accurately detected and quantified using analytical techniques such as atomic absorption spectroscopy or inductively coupled plasma mass spectrometry.

Other methods like filtration, evaporation, and distillation serve different roles in sample processing or concentration but do not specifically prepare samples in the context of metals analysis. Filtration is used to remove particulates from a liquid sample but does not necessarily dissolve metals. Evaporation is generally used to concentrate solutions or remove solvents rather than prepare samples for direct metals analysis. Distillation involves separating components based on different boiling points and is not suitable for the comprehensive digestion of complex samples containing metals. Thus, digestion is the most appropriate and effective method to prepare samples for accurate metals testing.