This European standard specifies a method for the determination of the total polyethylene glycol content (PEG) of aromatic and aliphatic non-ionic surface active agents of the type R-(ethoxy)p*-OH, where p*is the mean ethylene oxide (EO) value. It applies for concentrations of PEG higher than approximately 0,1 g/100 g of the laboratory sample. The method is applicable up to a degree of ethoxylation of at least 25 for products which are soluble in mixture of methanol and water where the volume fractions are 80% and 20%. Long-chain products with a low degree of ethoxylation, such as tallow alcohol x 5 EO, are not soluble, and require an amended preliminary tr