Method for measuring optical brighteners in environmental water

A method for measuring the concentration of optical brighteners in an environmental water source comprising: collecting a sample of water from an environmental source; adding to the sample an organic solvent that is immiscible with water, where the volume of the organic solvent is 5% or less of the volume of the water sample; adding to the water and organic solvent mixture cetyl trimethylammonium bromide as a detergent/phase-transfer agent and agitating the resultant mixture; allowing the water and organic solvent to re-separate following agitation and then removing the organic solvent from the mixture; adding the organic solvent to water or an aqueous solvent, where the volume of water or aqueous solvent is 5% or less of the volume of organic solvent; and collecting the water and detecting the presence of optical brighteners in the water via fluorescence. A preferable organic solvent is chloroform. Also claimed are: a kit for measuring the concentration of optical brighteners comprising cetyl trimethylammonium bromide; and the use of cetyl trimethylammonium bromide in a method or kit for measuring the concentration of optical brighteners in an environmental water source. Measurement of optical brighteners in fresh or sea water may be used to detect sewage contamination.