Metal Analysis: Which Digestion Method is Best?

Metals are extremely abundant, comprising almost three quarters of all naturally-occurring compounds on earth. Metals that are extracted from the earth tend to also be combined with one another to form alloys. These alloys, like carbon and stainless steels, are widely used as construction materials so accurate assessment of their composition is vital. On the flip side, trace metal detection is important to our environment and food and water supply which makes it imperative to assess quality and prevent potential hazards to human and animal health. This sheer diversity of applications has naturally given rise to a range of metal analysis techniques.

Although some solid metal analysis methods exist, solution-based approaches form the primary means of alloy composition and trace metal analysis. The ColdBlockTM ­digestion technique has emerged as a leading system for accurate, efficient, and safe decomposition of simple and complex matrices for metal speciation.

Here we will discuss a few proven methods to demonstrate the applicability of ColdBlockTM digesters to certain alloy types.

316L Stainless Steel

A low carbon stainless grade with added molybdenum for greater anti-corrosivity, type 316L stainless steel is an extremely popular engineering-grade alloy. We have demonstrated effective digestion of 316L steel chips for metal analysis, using aqua regia. Digesting the samples for only 15 minutes yields excellent recovery of elements with high reproducibility.

UNS A92024

Aluminium alloys under the 2024 grade are often deployed in the aerospace industry due to its high strength-to-weight characteristics. This is partially a result of carefully balanced alloying chemistry, with a primary alloying component of copper.

We have developed an ideal digestion method for A92024 metal analysis, once again using a standard aqua regia solution. Chemists can expect excellent reproducibility with values meting certified concentrations.

UNS S43100

Grade 431 stainless steels feature excellent mechanical properties with good corrosion resistance, making them suitable for a wide range of intricate components in harsh environments (i.e. marine engineering). They feature high chromium contents and low nickel, with additional trace-level alloying elements.

A similar method to the A92024 metal analysis technique can be used for reproducible digestion of UNS S43100 samples. The same sample—solvent concentration is used, with for a similar digestion time of 20 minutes.

Interested in more metal analysis methods?

This is a brief selection of digestion methods for specific alloys prior to elemental analysis. These procedures are specific to the samples digested and may need modification for different sample types or sizes to yield the same quality of results.

Interested in using the ColdBlockTM digestion technique in your metals analysis workflow? Simply contact a member of the team today.