This International Standard specifies a spectrophotometric method for the determination of hydroquinone in photographic processing waste.

This method can be applied to samples containing hydroquinone in the concentration range of 200 μg/l to 4 000 μg/l; aminophenols and phenylenediamines should also be determined by this method. However, sulfonated hydroquinones or products from the further oxidation of benzoquinone will not be determined.