An insider guide to analytical testing

With a wide variety of analytical testing techniques available, it can be hard to know which one is the best choice. Keep reading to learn when testing is necessary, what techniques are available, and when to use each method.

Do I need analytical testing?

Conducting analytical testing for your product isn’t the only way to verify environmental compliance. Many companies choose a documentary approach, collecting documentation from manufacturers and suppliers to assemble a technical file. There are usually guidelines like the RoHS IEC 63000 standard to ensure you have the correct information. Industry workers often favor this approach due to its cost-effectiveness and convenience, especially when multiple products share components.

However, there are times when this documentation may not be available, especially when dealing with manufacturers from different regions. For example, some American companies may not be familiar with European regulations like RoHS or EU REACH. They could also provide documentation that’s incomplete or otherwise untrustworthy. In such cases, it might be necessary to turn to analytical testing.

An overview of common analytical testing methods

Gas chromatography mass spectrometry 

One of the most popular testing methods is gas chromatography mass spectrometry (GC-MS). Professionals often use GC-MS to test for complex organic substances.

The GC-MS process has two distinct stages: sample separation through the gas chromatograph (GC) and subsequent analysis in the mass spectrometer (MS). Using both techniques together is highly effective because MS offers much more specificity than GC alone, and the GC separation improves the clarity and readability of the MS results.

The most significant limitation of GC-MS is that the sample must be in gas form – which means it can only test for substances that easily evaporate, also called volatile substances. As a result, many of the substances that GC-MS can detect are organic compounds.

Below is a summary of the restricted substances that GC-MS can test for:

RoHS – BBP, DIBP, and the phthalates

EU REACH –All volatile compounds

Halogen-free Requirements –All volatile compounds

US TSCA 5-PBT –All compounds

EU POP – All compounds

One downside to using GC-MS is that preparing solid samples can be difficult for someone with little chemistry training. Extracting all the analytes, especially semi-volatile ones, can be complex for electronic parts and will require someone with a working knowledge of derivation chemistry to do correctly. However, when testing for regulations like EU POP and US TSCA 5-PBT, the increased labor requirements may be balanced out by the ability to conduct a comprehensive analysis with a single test.

X-ray fluorescence

X-Ray Fluorescence (XRF) is an analytical technique that professionals use to detect heavy metals. The method works by directing an X-ray beam at the sample, prompting the atoms to emit photons. Since the photons are unique to each element, we can analyze them to determine which substances are present.

A significant advantage of XRF is the minimal requirements for sample preparation. In contrast to GC-MS, we can analyze solid samples in their original state, with only minor cleaning necessary. This saves time and reduces the technical expertise required for sample preparation, making XRF a more cost-efficient and accessible analytical method.

In addition, there are many handheld XRF devices on the market. These are especially useful for testing large equipment pieces, where obtaining smaller samples may be impractical. Additionally, the non-destructive nature of XRF analysis allows workers to examine valuable equipment without causing any damage.

However, like GC-MS, XRF is limited in its capacity. It can only detect substances composed of individual elements, such as lead or nickel, rather than compounds like BPA or DEHP. It’s also unable to differentiate between different forms of the same element (for example, it can detect chromium but not chromium 6+, which RoHS restricts. In addition, weaker handheld instruments usually have trouble detecting elements lighter than magnesium.

Below is a summary of the restricted substances that XRF can test for:

RoHS – Cadmium, Chromium, Mercury, Lead

EU REACH – Arsenic, Cadmium, Chromium, Mercury, Nickel, Lead

EU Battery Directive – Cadmium, Mercury, Lead

Halogen-free Requirements – Bromine, Chlorine, Fluorine (depending on the strength of the instrument)

Wet chemistry 

Wet chemistry encompasses a broad range of analytical techniques that require manual testing or handling of the sample. Some examples of wet chemistry techniques are:

Titrations – This method involves determining the concentration of a substance by reacting it with another substance of a known concentration.

Sample Extraction – This technique involves extracting the targeted substance from a material by dissolving it in a liquid solution, enabling further analysis.

Precipitation Reactions – In this method, the targeted substance is dissolved and reacted with another aqueous substance, forming an insoluble precipitate that can be analyzed.

Chemistry labs often use wet chemistry used alongside instrumental methods since it’s time-consuming, requires high expertise, and usually offers less precision than instrumental techniques. However, we should not overlook the utility of wet chemistry methods.

This is especially true for RoHS testing - since XRF cannot detect chromium 6+, a wet chemistry technique will be required to determine if the substance is present.

Wet chemistry is also necessary when preparing solid samples for instruments like GC-MS, which require the sample to be liquid or gas. This is especially relevant to electronics suppliers, since their materials are almost always solid.

Each characterization method possesses distinct advantages, disadvantages, and limitations. Here is a brief overview of which techniques you can employ for various environmental regulations:

*This column indicates when you would need to use wet chemistry to supplement GC-MS and XRF analysis rather than the capabilities of wet chemistry on its own.

When to use each analytical testing method:

RoHS – To test for all ten RoHS substances, you would need to use the three methods in conjunction. XRF would be necessary for the metals (lead, mercury, chromium, and cadmium), GC-MS for the compounds, and wet chemistry for chromium 6+.

EU REACH – XRF could detect arsenic, cadmium, chromium, mercury, nickel, and lead. GC-MS could detect most, if not all, of the remaining compounds.

EU Battery Directive – XRF can analyze all the substances of this directive.

Halogen-free Requirements – Both XRF and GC-MS can test for halogenated substances, with a few exceptions:

GC-MS could not test for non-volatile halogenated substances such as metal halides. However, the halogenated substances that electronic manufacturers typically use are volatile organic compounds. In contrast, XRF would be able to detect the presence of halogens but not the presence of individual compounds. Also, some low-strength instruments (such as handheld devices) may have trouble detecting fluorine.

US TSCA 5-PBT and EU POP: The substances restricted under these regulations are VOCs – therefore, GC-MS can test for these regulations in full.

This article was written by Beza Getachew, project manager at Enviropass, a consultancy that provides environmental compliance assistance in the electronics. To learn more about their work visit the Enviropass website.