ABSTRACT
Water is an essential resource for all living species, including human. Surface and subsurface water supplies accumulate many chemical constituents from both natural and anthropogenic sources. While knowledge about the effects of these accumulated impurities on biological, agricultural, and industrial systems is expanding, it is still limited in scope. It is therefore necessary to analyze a range of natural waters (surface waters, e.g., rivers, streams, lakes, reservoirs, oceans, and seas; precipitation, e.g., rain, dew, hail, and snow; groundwater), polluted waters (e.g., industrial ef uents and sewage sludge), and puri ed waters (e.g., drinking water and distilled water). Many laboratories deal with the determination of heavy metals, carbon, nitrogen, and phosphorus in natural water samples. But such samples also contain numerous dissolved organic substances (mainly alcohols, aldehydes, carboxylic acids, and macromolecular compounds with several functional groups such as humic and fulvic acids) that could affect the complexation of the analyte or displace the retained metal complex from the stationary phase, so these competitive ligands need to be decomposed before instrumental analytical techniques can be applied. Therefore, the rst step in the chemical analysis of a water sample is its proper preparation.
