Centexbel screens and analyzes PFOA in various steps:
Screening Fluorine and PFOA
When a consumer product is screened for risk components, we start by testing for the presence of Fluorine.
We can perform this test via SEM electron microscopy with EDX detection. The electrons of the SEM excite the Fluorine that emits specific X-rays that can be measured. This screening is impossible to perform with a classical XRF system with EDX detection. The presence of Teflon in Teflon membranes and finishes with a relatively high content can also be detected and identified by FTIR spectroscopy.
The presence of Fluorine may indicate the presence of residual PFOA
To check whether the amount is significant we perform a screening on LCMS of a general solvent extract, which will give us a decisive answer. Together with PFOA, other substances are detected, such as nonylphenol and nonylphenol ethoxylates, azodicarbonamide and UV stabilizers (REACH SVHC parameters).
Quantitative determination of PFOA
The special feature of the PFOA determination is that the substance is detected down to a very low limit, while the method itself involves risks of contamination. Teflon is used in the production of high-purity water, analytical standards and chemicals, as well as in the analysis equipment itself. Therefore, a distinction must be made between "background PFOA" and the PFOA from the sample itself.
Triple Quad LCMS
Centexbel uses Triple Quad LCMS devices from ABSciex to perform a quantitative analysis. These devices are also used for doping analyses, trace analysis in food and the medical sector.
It enables us to achieve very low detection limits, which is a necessity in view of e.g. Norway's limit of 1µg/m2 for textiles, carpets and other coated articles. The limit has to be met regardless of the weight of the material, which makes the analysis even more complex.
The Triple Quad LCMS allows us to measure PFOS (perfluorosulfonic acid) as well as perfluoroalkylic acids (C9 to C14).
In practice, when C8 fluorocarbon technology is used, the higher even alkyl compounds (C10-; C12-, C14-) are also always found. The content is lower. With the currently common C6 technology, a low amount of C8 (PFOA) also appears to be present in an analogous way. However, when the technology is properly applied, the content is below the strict Norwegian limit for PFOA.
Because of the burning topicality of the issue, there are many evolutions to be noted in the field of:
Very recently, the POPs regulation limited PFOA and PFOA-related substances (including salts and substances that can degrade into PFOA) to 25 ppb and 1000 ppb, respectively.
Raman spectroscopy is proving to be a good technique to elucidate the structure of perfluoro compounds.
In chromatography, the trend toward ever lower detection limits continues.