252-254In this article development and optimization
of visually evaluable dry-reagent test strip technique for qualitative and semi-quantitative
estimation of hardness of water has been described. The hardness of water is based
on its 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 sector is
essential. Presently, calorimetric assay and test kit methods are commonly used,
however, they are expensive and require trained persons to perform the test. The
dry reagent strip developed in the laboratory is quick, simple and economical. It
is based on specific chromogen immobilized on to a pad which reacts with calcium
present in water and
thereby changes the colour of the strip
from purple to blackish blue. The change in colour is visible with naked eyes and
can be compared with the colour chart