Need help finding the right GC-MS method to prove total solvent evaporation in cured metal coatings
Hi Everyone, we manufacture printed metal cans (for paints, thinners, general cans, etc.).
We are currently filling out a REACH / SVHC compliance declaration form for a customer. Our liquid formulations—specifically a White Base Coating and a Clear Varnish—contain Butyl Carbitol (CAS 112-34-5, around 5-20%) and Toluene (CAS 108-88-3, around 1-10%) as carrier solvents.
According to REACH Annex XVII, Butyl Carbitol is heavily restricted specifically for spray paints/aerosols. Our product is a standard liquid industrial coating applied via rollers, and the solvents are supposed to evaporate 100% during the thermal oven curing/drying process. Technically, the final finished good (the dried, cured metal sheet) should contain 0% active liquid solvent.
To satisfy our customer's auditors and prove that these solvents have completely volatilized, we want to send the fully cured/dried metal sheet samples to a 3rd party commercial lab for a quantitative test. Our goal is to get a "Not Detected" (ND) report.
However, local commercial labs are turning us down because this specific service isn't in their standard routine catalog. One international lab asked us to provide the specific standard testing method/protocol so their method validation team can check if their GC-MS setup can handle it.
My questions for the analytical/coating chemists here:
- What is the standard international test method (ASTM, ISO, EPA, etc.) for analyzing residual volatile organic solvents trapped inside a fully cured/dry paint film?
- How is the sample preparation usually done for this kind of matrix? Should it be a solvent extraction after scraping the dry film, or is there a better headspace/pyrolysis GC-MS setup commonly used for this?
Any insights, documentation references, or advice from anyone who has dealt with REACH compliance for cured coatings would be highly appreciated!