Analysis of water chemistry
Methodology
Methodology
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To ensure consistency and repeatability, the methods use in the chemical analysis of water samples are often agreed and published at a national or state level. By convention these are often referred to as "Blue book".

Certain analyses are performed in\-field (e.g. pH, specific conductance) while others involve sampling and laboratory testing.

The methods defined in the relevant standards can be broadly classified as:
* *Conventional wet chemistry* including the [Winkler method](/wiki/Winkler_method "Winkler method") for [dissolved oxygen](/wiki/Dissolved_oxygen "Dissolved oxygen"), [precipitation](/wiki/Precipitation_%28chemistry%29 "Precipitation (chemistry)"), [filtration](/wiki/Filtration "Filtration") for solids, acidification, neutralization, [titration](/wiki/Titration "Titration") etc. Colorimetric methods such as [MBAS assay](/wiki/MBAS_assay "MBAS assay") which indicates [anionic](/wiki/Anion "Anion") [surfactants](/wiki/Surfactant "Surfactant") in water and on site [comparator](/wiki/Comparator "Comparator") methods to determine [chlorine](/wiki/Chlorine "Chlorine") and [chloramines](/wiki/Chloramine "Chloramine"). [Nephelometers](/wiki/Nephelometer "Nephelometer") are used to measure solids concentrations as turbidity. These methods are generally robust and well tried and inexpensive, giving a reasonable degree of accuracy at modest sensitivity.
* *Electro chemistry* including [pH](/wiki/PH "PH"), [conductivity](/wiki/Conductivity_%28electrolytic%29 "Conductivity (electrolytic)") and dissolved oxygen using oxygen electrode. These methods yield accurate and precise results using electronic equipment capable of feeding results directly into a laboratory data management system
* [Spectrophotometry](/wiki/Spectrophotometry "Spectrophotometry") is used particularly for metallic elements in solution producing results with very high sensitivity, but which may require some sample preparation prior to analysis and may also need specialized sampling methods to avoid sample deterioration in transit.
* [Chromatography](/wiki/Chromatography "Chromatography") is used for many organic species which are volatile, or which can yield a characteristic volatile component of after initial chemical processing.
* [Ion chromatography](/wiki/Ion_chromatography "Ion chromatography") is a sensitive and stable technique that can measure [lithium](/wiki/Lithium "Lithium"), [ammonium](/wiki/Ammonium "Ammonium") NH4 and many other low molecular weight ions using [ion exchange](/wiki/Ion_exchange "Ion exchange") technology.
* [Gas chromatography](/wiki/Gas_chromatography "Gas chromatography") can be used to determine [methane](/wiki/Methane "Methane"), [carbon dioxide](/wiki/Carbon_dioxide "Carbon dioxide"), [cyanide](/wiki/Cyanide "Cyanide"), oxygen, nitrogen and many other volatile components at reasonable sensitivities.
* [Mass spectrometry](/wiki/Mass_spectrometry "Mass spectrometry") is used where very high sensitivity is required and is sometimes used as a back\-end process after [gas liquid chromatography](/wiki/Gas_liquid_chromatography "Gas liquid chromatography") for detecting trace organic chemicals.
Depending on the components, different methods are applied to determine the quantities or ratios of the components. While some methods can be performed with standard laboratory equipment, others require advanced devices, such as [inductively coupled plasma mass spectrometry](/wiki/Inductively_coupled_plasma_mass_spectrometry "Inductively coupled plasma mass spectrometry") (ICP\-MS).

### Research

Many aspects of academic research and industrial research such as in pharmaceuticals, health products, and many others relies on accurate water analysis to identify substances of potential use, to refine those substances and to ensure that when they are manufactured for sale that the chemical composition remains consistent. The analytical methods used in this area can be very complex and may be specific to the process or area of research being conducted and may involve the use of bespoke analytical equipment.


Can mass spectrometry detect non-ionic substances?