Oct 26, 2021 · Standard 40-mL glass screw-cap VOA vials with PTFE-lined silicone septa may be used for liquid matrices. Special 40-mL VOA vials for purge-and-trap of solid samples are described in Method 5035. VOA vials for headspace analysis of solid samples are described in Method 502. Standard 25-mL wide-mouth glass containers may be used.