Water-tracing compounds, development

Water-Tracing Compounds. Another application of these fluorescent pyridones has been the development of a series of coaipounds useful as ground-water tracers. Smart and Laidlaw have outlined several qualities desirable in fluorescent water-tracing compounds (.18). 

Development of extraction-free photometric procedures for the determination of traces of metals for which hygienic and environmental regulations have been established is an urgent problem. For solution of this problem we used as an organic reagent l-(2- pyridylazo)-naphtol-2 (PAN) which forms intensely coloured complex compounds with many metals and is frequently used for their extraction-photometric determination however these procedures did not find wide application in water analysis due to lack of selectivity and necessity of using organic solvents. 

The increased use of IV-methyl carbamate insecticides in agriculture demands the development of selective and sensitive analytical procedures to determine trace level residues of these compounds in crops and other food products. HPLC is the technique most widely used to circumvent heat sensitivity of these pesticides. However, HPLC with UV detection lacks the selectivity and sensitivity needed for their analysis. In the late 1970s and early 1980s, HPLC using post-column hydrolysis and derivatization was developed and refined with fluorescence detection to overcome these problems. The technique relies on the post-column hydrolysis of the carbamate moiety to methylamine with subsequent derivatization to a fluorescent isoindole product. This technique is currently the most widely used HPLC method for the determination of carbamates in water" and in fruits and vegetables." " ... 

In summary, the development of materials for the extraction of pesticides from water samples has progressed from simple liquid-liquid extraction for the principal active compound to sophisticated SPE media capable of exclusively trapping the target pesticide and metabolites selectively. The development of alkyl bonded phase silica cartridges and extraction disks combined with on-line extraction techniques is currently the principal means used for the extraction and trace enrichment of pesticides and metabolites from water. 

Capillary zone electrophoresis coupled with fast cyclic voltammetric detection was developed by Zhou et al. [27] for the separation and determination of OTC, TC, and CTC antibiotics. All compounds were well separated by optimization of pH and complexation with a boric acid sodium tetraborate buffer. The detection limit using fast on-line cyclic voltammetric detection with Hg-film-microm electrode was 1.5 x 10-6 mol/L for OTC (signal to noise ratio > 2). A continuous flow manifold coupled on-line to a capillary electrophoresis system was developed by Nozal et al. [28] for determining the trace levels of OTC, TC, and DC in surface water samples. 

Bacus A scrubbing process for removing olefins and carbon monoxide from gas streams. The adsorbent is a solution of a copper compound that is not deactivated by traces of water. Developed by D. Haase of Herr Haase, Nixon, TX. 

GEODE [General Electric organic destruction] A development of the Ultrox process in which a combination of ozone and ultraviolet radiation is used to oxidize traces of organic compounds in water. Developed by the General Electric Company and demonstrated at the Commonwealth Edison nuclear power plant at Dresden, IL, in 1989. The requirement was to reduce the concentration of total organic carbon in the process and makeup waters to the low parts-per-billion range. 

Many pesticides degrade to polar products that form organic anions in a water matrix. These are sometimes missed due to the difficulty in extracting trace amounts of the ionic material from a water matrix. A recently developed anion exchange procedure for isolating acidic compounds from dilute aqueous solutions (10-12) was used for recovering the anionic material from liquid samples collected from the two pits. 

If the size of the literature is a reliable indicator, the analysis of compo-uents fotmd In nvironmfntnl samples has not been developed t the same extent as clinical applications of re versed-phase chromatography. More attention has been paid to the analysis of volatile species by gas phase chromatography. This is due in part to the difficulty in identifying large molecular weight complex molecules which are present in water at trace levels. However, determination of a variety of analytes in water, soil, or other matrices has been reported and the wider use of RPC in the evaluation of water quality especially can be expected. The apolar phases used in RPC may be a boon in the determination of dilute analytes. Frei (4M) has discussed how relatively unpolar compounds dissolved in water can be concentrated at the top of a reversed-phase column and then eluted as a narrow band with an appropriate solvent. This technique can be used for the analysis of environmental samples in which the analyte of interest is in exceedingly low concentration. 

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