Ova 2000

Cipress Model CYSY-1B (basic system) CY57-1H (high-sensitivity system)

phosphorus-containing insecticides, carboxy methyl succinate, isopropylmethyl phosphonofluoridate, S-2 (disopropylamino)-ethyl-O-ethylmethyl phosphonothioate and 2,3 dichloro-1,4-naphthaquinone.

The technique has also been used to determine iodine, organic nitrogen and phosphorus, total inorganic carbon and chemical oxygen demand.

Visible spectrophotometers are commonly used in the water industry for the estimation of colour in a sample or for the estimation of coloured products produced by reacting a colourless compound of the sample with a reagent, which produces a colour that can be evaluated spectrophotometrically.

Some commercially available instruments, in addition to visible spectrophotometers, can also perform measurements in the UV and near IR regions of the spectrum. These have not yet found extensive application in the field of water analysis.

Suppliers of visible spectrophotometers are reviewed in Table 1.2.

1.1.3.2 Ultraviolet spectrometry

This technique has found limited application in water analysis: aliphatic, aromatic and polaromatic hydrocarbons, phenols, anionic and cationic surface active agents, saturated aliphatic halogen compounds, nitriloacetic acid and mimic and fulvic acids. The technique has also found application in the determination of total and dissolved organic carbon in water.

1.1.3.3 Luminescence and fluorescence spectrometry

Spectrofluorimetric methods have been described for the determination of polyaromatic hydrocarbons, carboxylic acids, phenols, amino acids, polychlorobiphenyls, nitriloacetic acid, carbamate insecticides and herbicides, chlorophyll and other plant pigments, and organotin and organoboron compounds.

Some applications of fluorescence spectrometry to the determination of polyaromatic hydrocarbons in water samples are summarized in Table 1.3. Generally speaking, concentrations down to the microgram per litre level can be determined by this technique with recovery efficiencies near 100%.

Potentially, fluorimetry is valuable in every laboratory, including water laboratories, for the performance of chemical analysis where the prime requirements are selectivity and sensitivity. While only 5- 10% of all molecules possess a native fluorescence, many can be induced to fluoresce by chemical modification or being tagged with a fluorescent molecule.

Luminescence is the generic name used to cover all forms of light emission other than that arising from elevated temperature (thermoluminescence). The emission of light through the absorption of UV or visible energy is called photoluminescence, and that caused by chemical reactions is called chemiluminescence. Light emission through the use of enzymes in living systems is called bioluminescence, the only known application of which to water analysis is the determination of adenosine triphosphate. Photoluminescence may be further subdivided into fluorescence, which is the immediate release (10-8s) of absorbed light

Table 1.2 Visible—ultraviolet—near infrared spectrophotometers

Spectra/ region

Range (run)

Manufacturer

Model

SirtgJe or double beam

Cost ronge

UV/visible

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