Test strip for free chlorine analysis
AssigneeIndustrial Test Systems, Inc.
InventorsVasili V. Ramana, Kami R. Yamuna, Ivars Jaunakais
Life of this patent
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Abstract
A colorimetric test strip useful for analysis of free chlorine is provided. In a preferred embodiment, 3,3',5,5'-tetramethylbenzidine is the colorimetric indicator. Beneficially, the carrier for the indicator has been treated to have a pH that eliminates chloramine interference. Advantageously, the indicator in free base form and a suitable water-soluble buffer may be deposited on the carrier using a combined solution of indicator and buffer.
Claims20
A colorimetric test strip useful for analysis of free chlorine, said test strip comprising a carrier bearing 3,3',5,5'-tetraalkylbenzidine having C1-C3 alkyl groups, wherein said alkyl groups may be the same or different, said carrier having been treated to have a pH effective to prevent chloramine interference.
A method for analysis of free chlorine, said method comprising contacting an unknown sample with a test strip comprising a carrier treated with a combined solution of an organic liquid-containing solution of 3,3',5,5'-tetraalkylbenzidine having C1-C3 alkyl groups, wherein said alkyl groups may be the same or different, and a water-containing solution comprising a buffer and effective to provide the treated carrier with a pH effective to prevent chloramine interference;
- and evaluating the coloration on said carrier.
A process for making a colorimetric test strip useful for analysis of free chlorine, said process comprising treating a carrier with a combined solution of an organic liquid-containing solution of 3,3',5,5'-tetraalkylbenzidine having C1-C3 alkyl groups, wherein said alkyl groups may be the same or different, and a water-containing solution comprising a buffer and effective to provide the treated carrier with a pH effective to prevent chloramine interference, and drying said carrier after said impregnation.
Dependencies are inferred from the claim text.