Triazine natural waters

Evgenidou, E. and Fytianos, K. Photodegradation of triazine herbicides in aqueous solutions and natural waters, J. Agric. Food Chem., 50(22) 6423-6427, 2002. 

Berg, M., S. Muller, and R. Schwarzenback (1995). Simultaneous determination of triazines including atrazine and their major metabolites hydroxyatrazine, desethylatrazine and deisopropylatrazine in natural water. Anal. Chem., 56 1860-1865. 

Carabias-Martinez, R., E. Rodriquez-Gonzalo, J. Dominquez-Alvarez, and J. Hemandez-Mendez (2002). Comparative study of separation and determination of triazines by micellar electrokinetic capillary chromatography and nonaqueous capillary electrophoresis Application to residue analysis in natural waters. Electrophoresis, 23 494—501. 

Sherma, J (1986). Determination of triazine and chlorophenoxy acid herbicides in natural water samples by solid phase extraction and quantitative thin layer chromatography. J. Liquid Chromatog., 9(16) 3433-3438. 

The increased rates of photodegradation of the triazine herbicides observed in the presence of naturally occurring sensitizers indicate that photodegradation plays a significant role in the dissipation of these herbicides in natural waters. With most of the sensitizers studied thus far, cyanuric acid was the stable end product, rather than complete mineralization of the triazine herbicide. 

Although hydrolysis of the triazine herbicides is temperature and pH dependent, these herbicides are considered to be hydrolytically stable under the pH and temperature conditions encountered in natural waters. However, the relatively slow hydrolysis rates in natural waters may be enhanced somewhat by the presence of dissolved organic carbon (DOC) (in the form of fulvic acids and a variety of low-molecular-weight carboxylic acids and phenols) that has been shown to catalyze the hydrolysis of several triazine herbicides. Although microbial degradation is probably the most important mechanism of dissipation of the triazine herbicides in soils, abiotic hydrolysis of these herbicides also occurs. Hydrolysis in soils is affected by the pH, organic matter (humic acid) content, and the type and content of clay in the soil. 

Under the pH and temperature conditions of natural waters, the various 2-chloro-, 2-methylthio-, and 2-methoxy-.v-triazine herbicides are generally considered to be stable in solution between pH 5 and pH 9, stable in neutral, weakly acidic and weakly alkaline media, and stable to hydrolysis at 20°C in neutral, weakly acidic, and weakly alkaline media (Pesticide Manual, 1997). Metribuzin, metamitron, and hexazinone are also considered to be stable under these conditions (Pesticide Manual, 1997). Such hydrolytic stability of the triazine herbicides is supported by hydrolysis studies (Rhodes, 1980 Widmer et al., 1993 Noblet et al, 1996 Hequet et al, 1997) that indicate either very slow rates of hydrolysis or no measurable hydrolysis (Table 23.3) under these conditions. 

Prados M, Paillard H, Roche P. Elydroxyl radical oxidation processes for the removal of triazine from natural water. Ozone Sci Eng 1995 17 183-194. 

Dzygiel P and Wieczorek P. Extraction of glyphosate by a supported liquid membrane technique. J. Chromatogr. A 2000 889 93-98. Chimuka L, Nindi MM, and Jonsson jA. Supported liquid membrane enrichment smdies of natural water samples apphed to liquid chromatographic determination of triazine herbicides. Int. J. Environ. Anal. Chem. 1997 68 429 145. 

A FIA method using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol was developed for the simultaneous determination of Fe and Zn in human hair [21]. The metod using sulfosalicyclic acid was developed for the determination of Fe in oil [22]. Iron(II) and total Fe in natural waters was determined with 3-(2-pyridyl)-5,6-diphenyl-l,2,4-triazine [23]. 

The first example comes from the field of environmental chemical analysis and considers SLM enrichment and determination of triazine herbicides from natural water samples [141]. It shows how simple manipulation of donor and acceptor phase pH, the simplest manner of transforming the analyte into a transportable form, can lead to an SLM system with high extraction efficiency. A porous PTFE membrane impregnated with water immiscible dihexyl ether was used as an organic solvent. The obtained detection hmit of triazines ranged from 0.03 to 0.16 pg/1 in natural waters with 20 min extraction time using simple UV detection. 

In a study covering a wide range of polar and acidic pesticides deethylatrazine and atrazine besides anilide, phenoxy acid, phenylurea, carbamates and other types of specific pesticides in river water were determined by ESI-LC-MS and MS/MS. Recoveries, depending on preconcentration steps, obtained with different SPE materials (PLRS-S, Hyshere-1, LiChrolut EN and Isolute ENV -i-) and at different pH values were reported [502]. Sixteen of the most widely used pesticides in Southern Italy were monitored in surface water samples taken in the Calabria region. Triazines were determined quantitatively by LC-UV and ESI-LC-MS(-i-) and were confirmed by MS [537]. In another study the simultaneous determination of 26 non-acidic (base and neutral e.g. triazine, carbamate, anilide, N-substituted amine, urea and organophosphorus type) and 13 acidic (sulfuron and phenoxy acid type) pesticides in natural waters was performed using ESI-LC-MS. Recoveries... 

R. Carabfas-Martmez, E. Rodrfguez-Gonzalo, J. Dominguez-Alvarez and J. Hemandez-Mendez, Determination of triazine herbicides in natural waters by solid-phase extraction and non-aqueous capillary zone electrophoresis, J. Chromatogr. A, 869, 451 61, 2000. 

Extracts of trace constituents in some types of relatively pure samples can also be spotted directly after concentration of the extract to a suitable volume. Any coextracted impurities must be resolved from the analyte by the TLC development or not detected by the visualization method used. To minimize the amount of coextractives, the least polar solvent that will quantitatively extract the analyte should be used, leaving as many polar impurities as possible unextracted. This method of sample preparation was used to determine triazine (74) and chlorophenoxy acid (75) herbicides in natural water samples by TLC with densitometry. 

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