Automatic colorimetry

Colorimetry. Copper (Duncombe 1963 Koops and Klomp 1977) or cobalt (Novak 1965) soaps of long-chain fatty acids (>C12) are soluble in chloroform and can be determined quantitatively by colorimetric determination of the extracted metal. Shipe et al. (1980B) have recently modified the original copper soap method to make it simpler, more rapid, and adaptable to automatic equipment. 

Nil Enzymatic Colorimetry-manual, automatic Fluorimetry Milk Human milk Koops et al. (1990) Christmass et al. (1998)... 

In Table 1.3 are listed the Instrumental techniques most frequently used for detection with automatic analysers of any kind. Molecular absorption spectrometry (colorimetry) is by far the commonest of such techniques, followed by potentlometry (pH measurements and use of selective electrodes). 

For determination of nitrites in clean aqueous solutions such as water, there is no need for extraction it is generally enough to filter the sample before it is injected into the FIA system. In some cases preconcentration of the sample may be necessary for determination of nitrite by FIA or sequential injection analysis (SIA). One such example would be direct nitrite determination in nonpolluted water samples where colorimetry is not sensitive enough to determine NO2 (Miro et al., 2000,2001). Preconcentration processes have been based on anionic exchange resins (Dowex 1-X8) (Wada and Hattori, 1971) or on ion pairs coprecipitated with microcrystalline biphenyl (Puri et al., 1998), or with naphthalene (Wang et al., 1998). Dialysis-FIA systems have been proposed for determination of nitrite in residual waters, and even a solid phase (monofunctional Cjg) which is held inside a glass column for an automatic SIA has been tried (Miro et ah, 2000). 

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