XRF Applications Blog

Thursday, December 27, 2007

XRF Applications: Bromine and Chromium Testing

XRF Applications: Bromine and Chromium Testing

Five elements are being tested for in various hazardous substance initiatives (RoHS, WEEE, Prop-65, etc).  Chosen due to their toxicity the elements include Cadmium (Cd), Lead (Pb), Mercury (Hg), Bromine (Br) and Chromium (Cr).  Three of the five elements (cadmium, lead, and mercury) can be tested for on a pass/fail basis using only x-ray fluorescence (XRF) technology.  Bromine and chromium, however, are slightly different.

The fact that bromine and chromium have both hazardous and non-hazardous states means that additional testing may be required after XRF scanning.  If an XRF system shows that a product does not exceed acceptable levels of bromine and chromium then the product ‘passes’ inspection and no further testing is necessary.  If, however, a product tested by XRF shows unacceptable levels of the elements and ‘fails’ then destructive testing is required to determine if the levels are the result of hazardous composition of the element (a true fail) or non-hazardous composition (would then pass).

Elemental and trivalent chromium are non-hazardous; it is the hexavalent chrome that is toxic and regulated.  Additional testing is required when any chrome is detected by an XRF instrument at a ‘failing’ level to determine the chromium composition. The common method for additional testing is the destructive Ion Chromatography (ICP) method; which will determine if the chrome is hexavalent, and therefore hazardous, or not – a final pass/fail can then be provided.

Similarly, elemental bromine does not require regulation but what bromine is bonded to will create the hazardous substance.  If an XRF test results in an unacceptable bromine level then further analysis would be completed with the Gas Chromatography/Mass Spectrometry (GC/MS) testing method.  Again, the additional testing can provide a final pass/fail result.

Though further testing is needed for some elements, XRF is still the quickest and easiest method of determining the content of these hazardous substances in a variety of materials.  XRF testing is also non-destructive, that is to say that the part could be used after being tested.  In the case of other testing methods (ICP or GC/MS), the part would need to be destroyed to calculate the amount of metals present.  XRF also has the added benefit of being a much more economical approach to testing/scanning of products.

- JGH/SC

• RoHS and Lead Testing