Final answer:
The preferred methods for trace metals analysis are mass spectrometry-based techniques like LC-MS/MS due to their high sensitivity, specificity, and the ability to handle complex sample matrices, with chromatographic separation enhancing accuracy and selectivity.
Step-by-step explanation:
The method of choice for trace metals analysis is typically based on the requirements for sensitivity, specificity, and the matrix of the sample. Techniques such as atomic spectroscopy, ion trap mass spectrometry, and liquid chromatography coupled with mass spectrometry (LC-MS/MS) are widely employed.
For a solution containing several metal ions, qualitative analysis, such as selective precipitation followed by filtration or centrifugation, can be used to identify the ions present. For example, adding 6 M HCl can precipitate insoluble chlorides like AgCl, PbCl2, and/or Hg2Cl2, indicating the presence of their corresponding cations.
However, for trace metal analysis, mass spectrometry techniques are often preferable due to their high sensitivity and specificity. Ion trap mass spectrometry can provide detailed structural information, while tandem mass spectrometry, like LC-Q-TOF MS/MS, offers high resolution and is ideal for quantitative high-throughput analysis.
When coupled with chromatographic separation, such as reversed-phase liquid chromatography (LC), mass spectrometry methods like multiple-reaction monitoring (MRM) offer enhanced selectivity and sensitivity, which are indispensable for analyzing complex matrices and attaining precise quantification of trace metals.