Abstract: A quantitative, sensitive method for monitoring low concentrations of isothiazolones in aqueous systems is provided. The method involves the adsorption of the isothiazolones on a suitable adsorbent, the desorption of the adsorbed isothiazolones, the breaking of the isothiazolone ring and the formation of a blue complex by the reaction of the broken isothiazolone ring with ferric chloride and potassium ferricyanide. The concentration of the isothiazolones is then determined by conventional colorimetric techniques.

Abstract: A quantitative method useful for field monitoring low concentrations of water soluble, polyacrylic acids in aqueous systems containing polyacrylic acids and other soluble ionic materials, such as ionic salts and phosphonates, is provided. The method involves adjusting the pH of the aqueous system to suppress the ionization of the polyacrylic acids followed by selective adsorption and concentration of the polyacrylic acids on a suitable adsorbent. Concentrated polyacrylic acids are then desorbed from the adsorbent and the concentration of the polyacrylic acids in the aqueous system is determined by conventional techniques.