IEC 62321-6

Chemical testing determines which substances are present in a material and at what concentrations. The output of this family is usually assessed against a RESTRICTION: is the substance banned, is it below the limit, does it have to be notified?

The most defining feature of the field is that restrictions CHANGE RAPIDLY. The REACH Annex XVII list expands regularly, the SVHC candidate list is updated every six months, the RoHS substance list takes on new items, the scope of the POPs regulation widens, and brand restricted substance lists are revised several times a year. When reading a chemical report it must therefore be stated which version of the list it was assessed against; a report obtained two years ago may fall short against today's list.

Methods are divided according to the type of analyte. ICP-OES, ICP-MS, AAS and XRF are used for elemental analysis; GC-MS, HPLC and LC-MS/MS for organic compounds; FTIR and Raman for structural identification; DSC and TGA for thermal characterisation.

XRF has a special place in the field and is often misused. Because it is fast, non-destructive and suitable for field use, it is very valuable as a screening tool: it answers within minutes whether a product contains lead or bromine. But XRF is an ELEMENTAL screening method and does not distinguish compounds. It sees the presence of bromine but does not say whether that bromine is a restricted flame retardant or a permitted compound. A definitive decision requires confirmation by wet chemistry.

Sample preparation is the invisible half of the result. A multi-component product — an electronic board or a shoe, for example — is not a homogeneous sample; each component must be separated and analysed individually. In a RoHS assessment this separation goes down to the "homogeneous material" level and the limits are applied at that level. Grinding the whole product and analysing it dilutes the restricted substance and hides it.

The detection limit and measurement uncertainty determine the quality of decisions in this field. A result falling just below a limit may be above it once uncertainty is taken into account. Accredited reports therefore declare the uncertainty, and a decision rule is applied in the conformity decision.

Declaration obligations go beyond analysis. SVHC notification, supply chain communication and product composition declarations are usually built from supplier data rather than from analysis; analysis is used to verify that data. A complete conformity file combines the two.