1. Scope

1. Scope
1.1 This test method covers the determination of total organic fluorine (TOF) in solid matrices by solvent extraction followed by combustion ion chromatography. This analyte, which is comprised of the organic fluorine contribution from a large number of compounds, are extracted from solid test specimens or subsamples with tetrahydrofuran (THF) then qualitatively and quantitatively determined by this test method.
1.1.1 This method measures compounds containing organic fluorine readily leached or soluble under the conditions of the extraction.
1.1.2 Depending on data usage, use of this test method may modify this test method but limit to modifications that improve performance while still meeting or exceeding the method quality acceptance criteria.
1.2.1 The concentration of TOF extracted is defined by the sampling and extraction process, therefore, modifications to the solvents, ratio of solvent to sample, or the extraction process may change the result, and if undertaken are required to be reported and documented as changes to the test method.
1.3 This method can be applied to solids. Use Practice E2935 or similar statistical tests to confirm that any modifications produce equivalent results on non-interfering samples. In addition, use Guide E2857 or equivalent statistics to re-validate the modified test.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

Keywords

PFAS; organic flourine

Rationale

There currently is no published method for TOF in a solid matrix that was specifically developed and validated for solid matrices inherent with Consumer and Related Products. The concept of extractable organic fluorine (EOF) is an established concept; however, most current or evolving EOF methods utilize methanol as the extraction solvent. Methanol is an effective extraction solvent for many classes of PFAS compounds, but also has many limitations including but not limited to it not being an effective extraction solvent for fluoropolymers. THF has been documented in research literature to be a much more effective extraction solvent that may allow this method to be closer to the “total” in TOF.
NOTE: there is still a significant gap in understanding the true efficacy of THF to extract a larger universe of PFAS compounds. For example, it is possible that while THF may be more effective at extracting fluoropolymers, it is possible that it is less effective at extracting certain classes of PFAS compounds that otherwise extract sufficiently in methanol. As such, the initial phase of this method development will be to validate the compositional nature of the proposed extraction solvent, which could in fact be mix of two or more solvents (and varying pH conditions).

The title and scope are in draft form and are under development within this ASTM Committee.