What is the purpose of using concentrated nitric acid in water analysis?

The use of concentrated nitric acid in water analysis is primarily for sample preparation, particularly for metals analysis. When analyzing for metals, it is crucial to ensure that the samples are properly digested to break down any complex matrices or organic matter that may interfere with the detection of metal ions. Concentrated nitric acid serves to decompose these materials, releasing metal ions into solution in their ionic forms, which allows for accurate measurement through various analytical techniques such as atomic absorption spectroscopy or inductively coupled plasma mass spectrometry.

By codifying samples in this manner, it increases the efficiency and effectiveness of the subsequent analysis, providing reliable results in determining the concentration of metals present in the water sample. This preparation step is vital in ensuring that any potential interferences are minimized and that the sample accurately reflects the metal content of the source water.