NOTE 1 By applying the method specified in this document, the concentration of free fluorotelomer alcohols (FTOH) in a sample cannot be correctly quantified if perfluoropolymers that release FTOH due to transesterification with the extraction solvent methanol are present in the sample.

NOTE 2 Some regulations (e.g. Reference [4]) also restrict perfluoropolymers having a linear or branched perfluoroheptyl group with the moiety (C₇F₁₅)C as one of the structural elements that can degrade to PFOA, e.g. polymers containing 2-perfluorooctylethanol (8:2 FTOH, CAS Registry Number^®1 678-39-7) bonded as esters. To determine whether these perfluoropolymers are intentionally present, it could be necessary to introduce an alkaline hydrolysis method to remove the 8:2 FTOH side-chain from the polymer. In addition, other FTOH, e.g. 6:2 FTOH or 10:2 FTOH, will be released from relevant perfluoropolymers by alkaline hydrolysis.^[3]