Hydroxyaromatic compounds at ppb levels in water were determined with cloud point preconcentration followed by high-performance liquid chromatography (HPLC) with UV absorption detection. The extraction efficiencies and preconcentration factors of cloud point extraction were enhanced by the addition of neutral electrolytes to the micellar solutions. This method was applied to the determination of hydroxyaromatic compounds at ppm levels in commercial dyestuffs. The dyestuff was dissolved in water

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... and pre-cleaned with a SAX cartridge packed with an anion-exchange resin; the effluent was then analyzed using the proposed cloud-point preconcentration, with subsequent determination by HPLC.