Arsenazo III test strip for rapid detection of hardness of water

In this article development and optimization of visually evaluable dry-reag ent test strip technique for qualitative and semi-quantitative estimation o f hardness of water has been described. The hardness of water is based on i ts alkaline earth content i.e. calcium and magnesium ions and their salts. The estimation of hardness of water in industry as well as in private secto r is essential. Presently, calorimetric assay and test kit methods are comm only used, however, they are expensive and require trained persons to perfo rm the test. The dry reagent strip developed in the laboratory is quick, si mple and economical. It is based on specific chromogen immobilized on to a pad which reacts with calcium present in water and thereby changes the colo ur bf the strip from purple to blackish blue. The change in colour is visib le with naked eyes and can be compared with the colour chart.