Inorganic materials like heavy metals in particular mercury, arsenic, lead, cadmium,
and other metals having high de is wide spread concern of the society when present
in high concentrations and can have lethal effects to ecosystem as well as human
health as shown in Fig. 1. Their accumulation can be due to leaching from waste
disposal, industrial wastes, burning of fossil fuels, mining and other human activities. Further, in worst case, their exposure may even lead to death of humans or
animals. Due to these reasons development of water monitoring technologies is the
prominent area of research these days. The colorimetric technique is one of the
preferred methods for the onsite detection of water pollutants because of the usage
simplicity and affordability i.e. in most cases observations can be made by naked
eyes without need of any expensive instrumentation for analysis. It does not require
any skilled manpower for the analysis and can be used by the general public.
Despite these advantages, the colorimetric techniques lack in accuracy and may not
be able to fulfil the criteria of low detection limits, as compared to other
Fig. 1 Common heavy metals with their permissible WHO limits and the health effects caused
due to their overdose
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R. Jain et al.