Atrazine water

Keywords granular activated carbon adsorption natural organic matter micro-pollutants atrazine water treatment water temperature... 

Atrazine and simazine arose principally as a result of their use in amenity situations but, since their ban for non-agriciiltiiral purposes, concentrations are generally declining. Fiowever, atrazine and simazine still have some agricultural uses (atrazine on maize and simazine on a wide range of crops), so the risk of pollution still exists when these pesticides are applied in either groundwater or surface water drinking water supply catchments. 

There are at least 22 chemical families of organic herbicides. Even a cursory treatment of the chemistry of these materials would be extensive. Herbicides of limited toxicity (Treflan, Atrazine) as well as extremely toxic ones (Paraquat. Dinoseb) are in use in many parts of the world. They range from water soluble to insoluble. The detailed chemistry of each should be determined prior to handling. 

The drinking water maximum contaminant level (MCL) set by the USEPA for altrazine is 0.003 mg/L and its Reference Dose (RfD) is 3.5 ingAcg-d. How many liters of water containing atrazine at its MCL would a person have to drink each day to e.xceed the RfD for this triazine herbicide ... 

Assuming that those exposed can be represented by a 70 kg individual, the volume of drinking water at the MCL to reach the RfD for atrazine is ... 

Figure 2.21 A gas cluomatogram of a sample of river water (2.25 ml) spiked at 5 ppb levels with 1, toluene 2, ethylbenzene 3, methoxybenzene 4, p-dichlorobenzene 5, dimethylphe-nol 6, dimethylaniline 7, chloroaniline 8, indole 9, dichlorobenzonitrile 10, tiichlorophe-nol 11, dinitrobenzene 12, tiifluranil 13, atrazine 14, phenantlnene. Reprinted from Journal of High Resolution Chromatography, 16, H. G. J. Mol et al., Use of open-tubular tapping columns for on-line extraction-capillary gas cluomatography of aqueous samples , pp. 413-418, 1993, with permission from Wiley-VCH.

Figure 13.10 LC-LC chromatogram of a surface water sample spiked at 2 p.g 1 with ati azine, and its metabolites (registered at 220 nm). Conditions volume of sample injected, 2 ml clean-up time, 2.60 min ti ansfer time, 4.2 min The blank was subtracted. Peak identification is as follows 1, DIA 2, HA 3, DEA 4, atrazine. Reprinted from Journal of Chromatography, A 778, F. Hernandez et al, New method for the rapid detemiination of triazine herbicides and some of thek main metabolites in water by using coupled-column liquid cliromatography and large volume injection , pp. 171-181, copyright 1997, with permission from Elsevier Science.

Figure 13.15 Chromatograms obtained by on-line ti ace enrichment of 50 ml of Ebro river water with and without the addition of different volumes of 10% Na2S03 solution for every 100 ml of sample (a) blank with the addition of 1000 p.1 of sulfite (b) spiked with 4 p.g 1 of the analytes and 1000 p.1 of sulfite (c) spiked with 4 p.g 1 of the analytes and 500 p.1 of sulfite (d) spiked with 4 p.g 1 of the analytes without sulfite. Peak identification is as follows 1, oxamyl 2, methomyl 3, phenol 4, 4-niti ophenol 5, 2,4-dinitrophenol 6, 2-chlorophenol 7, bentazone 8, simazine 9, MCPA 10, atrazine. Reprinted from Journal of Chromatography, A 803, N. Masque et ai, New chemically modified polymeric resin for solid-phase extraction of pesticides and phenolic compounds from water , pp. 147-155, copyright 1998, with permission from Elsevier Science.

One of the first examples of the application of reverse-phase liquid chromatography-gas chromatography for this type of analysis was applied to atrazine (98). This method used a loop-type interface. The mobile phase was the most important parameter because retention in the LC column must be sufficient (there must be a high percentage of water), although a low percentage of water is only possible when the loop-type interface is used to transfer the LC fraction. The authors solved this problem by using methanol/water (60 40) with 5% 1-propanol and a precolumn. The experimental conditions employed are shown in Table 13.2. 

K. Grob-Jr and Z. Ei, Coupled reversed-phase liquid cliromatography-capillary gas cliromatography for the determination of atrazine in water , 7. Chromatogr. 473 423-430(1989). 

The TIC trace from the LC-MS analysis of an extracted river water sample, spiked with 3 p.g dm of atrazine and three of its degradation products, is shown in Figure 3.30. The presence of significant levels of background makes confirmation of the presence of any materials related to atrazine very difficult. The TIC traces from the constant-neutral-loss scan for 42 Da and the precursor-ion scan for m/z 68 are shown in Figure 3.31 and allow the signals from the target compounds to be located readily. 

Ureides (e.g., diuron, linuron) and triazines (e.g., atrazine, simazine, ametryne) all act as inhibitors of photosynthesis and are applied to soil (see Figure 14.1 for structures). They are toxic to seedling weeds, which they can absorb from the soil. Some of them (e.g., simazine) have very low water solubility and, consequently, are persistent and relatively immobile in soil (see Chapter 4, Section 4.3, which also mentions the question of depth selection when these soil-acting herbicides are used for selective weed control). 

With the acceptable concentrations of herbicides in drinking water being taken to very low levels by some regulatory authorities (e.g., the EC), there has been interest in very low levels of atrazine present in some samples of groundwater and in drinking water. This finding illustrates the point that mobility of pesticides becomes increasingly evident as sensitivity of analysis improves. 

Acero JL, K Stemmier, U van Gunten (2000) Degradation kinetics of atrazine and its degradation products with ozone and OH radicals a predictive tool for drinking water treatment. Environ Sci Technol 34 591-597. 

Nelieu S, L Kerhoas, J Einhorn (2000) Degradation of atrazine into ammeline by combined ozone/hydrogen peroxide treatment in water. Environ Sci Technol 34 430-437. 

Supercritical fluid extraction (SFE) is generally used for the extraction of selected analytes from solid sample matrices, but applications have been reported for aqueous samples. In one study, recoveries of 87-100% were obtained for simazine, propazine, and trietazine at the 0.05 ug mL concentration level using methanol-modified CO2 (10%, v/v) to extract the analytes, previously preconcentrated on a C-18 Empore extraction disk. The analysis was performed using LC/UV detection. Freeze-dried water samples were subjected to SFE for atrazine and simazine, and the optimum recoveries were obtained using the mildest conditions studied (50 °C, 20 MPa, and 30 mL of CO2). In some cases when using LEE and LC analysis, co-extracted humic substances created interference for the more polar metabolites when compared with SFE for the preparation of the same water sample. ... 

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