Test strip for free chlorine analysis
First Claim
1. 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.
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Accused Products
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.
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Citations
20 Claims
- 1. 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.
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14. 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.
- View Dependent Claims (15, 16)
- 17. 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.
Specification