The method described is applicable to the determination of benzene, methylbenzene (toluene), dimethylbenzenes (xylenes) and ethylbenzene (abbreviated hereafter to BTX) in water and waste water in concentrations above 5 µg/l. High concentrations may be determined by diluting the extract. A number of further derivatives and nonpolar compounds with similar boiling points may also be determined by this method. The applicability of the methods should be verified in these cases for the particular water sample.