Atrazine technique

ELP fusion protein (Fig. 9, center). It was shown that picomolar levels of ELP fusion proteins could be purified via ELP coaggregation [47, 48]. The value of this technique was shown by the purification of low levels of ELP fused to an anti-atrazine antibody [49]. 

Supercritical fluid chromatography (SEC) was first reported in 1962, and applications of the technique rapidly increased following the introduction of commercially available instrumentation in the early 1980s due to the ability to determine thermally labile compounds using detection systems more commonly employed with GC. However, few applications of SEC have been published with regard to the determination of triazines. Recently, a chemiluminescence nitrogen detector was used with packed-column SEC and a methanol-modified CO2 mobile phase for the determination of atrazine, simazine, and propazine. Pressure and mobile phase gradients were used to demonstrate the efficacy of fhe fechnique. 

Wu et al. [388] carried out measurements of the enrichment of Atrazine on the micro surface water of an estuary. These authors used a micro surface water sampling technique with a 16 mesh stainless steel screen collecting bulk sampled from the top 100-150 pm of the surface. Atrazine concentration in the actual micro surface was estimated to vary in the range 150-8850 pg/1. 

Lopez-Avila et al. [36] used a stable isotope dilution gas chromatography-mass spectrometric technique to determine down to O.lppb of pentachlorophenol (also Atrazine, Diazinon and lindane) in soil. Soil samples are extracted with acetone and hexane. Analysis is performed by high-resolution gas chromatography-mass spectrometry with mass spectrometer operated in the selected ion monitoring mode. Accuracy greater than 86% and a precision better than 8% were demonstrated by use of spiked samples. 

The hydrolysis reaction is carried out in a sealed test-tube in 1 N hydrochloric acid at 150 °C for 8-16 h. The resulting solution is made basic and the mixture is then dansylated [156]. Triazines such as atrazine, simazine and propazine yield different combinations of free amines on hydrolysis, thus enabling their characterization using the fluorogenic labeling technique. The limits of detection range from 5 to 10 ng per spot. Concentrations of 0.05 ppm in food crops may be determined. 

Since many herbicides are crop-specific, herbicide concentrations in farmer s fields are routinely monitored to determine herbicide carry-over. Residual herbicides from the previous year adversely affect alternate crops grown to be grown during the subsequent season. There has been a limited amount of literature describing the successful SFE of herbicides such as sulfonylureas, diruron, linuron, and s-triazines spiked on various solid matrices with COj and methanol modified C02 (1,8-11). Summarized here are the differences in recovery of atrazine from an actual farmer s soil sample as a function of extraction temperature and pressure using both CO2 and methanol modified COj. Also shown are comparisons of recoveries from real vs. spiked samples and also static vs. dynamic modifier addition techniques. 

Procedure. Seven extractions of the same soil sample were performed at temperatures between 40°C and 80°C, pressures between 4000 psi and 7000 psi, and also with and without modifying the COj with methanol. Both static and dynamic modifier techniques were used. CO2 alone and static modifier addition procedures were performed with a SFE System 1200 while dynamic modifier addition procedures were executed with a SFE System 2200. The spiked sample was prepared by pipetting a much higher concentration of atrazine in ethyl acetate onto the soil matrix... 

Su, P.-H. 1994. Sorption studies of atrazine using continuous stirred-flow and batch techniques. Master s thesis. Utah State University, Logan, UT. 

Hyphenated chromatographic techniques of various types (e.g., HRGC/HRGC and HPLC/HRGC) are being used in conjunction with a variety of detectors to improve detectability, increase specificity, and reduce cleanup costs for routine analysis. Vuruls et al. (1992) reported ng/L quantitation for aqueous atrazine samples by LC/GC/MS. 

Researchers have also used immunoassay techniques for analysis of triazines in soil leachate. Tasli et al. (1996), for example, analyzed soil water from an irrigated com plot by immunoassay and GC/NPD. Amistadi et al. (1997) analyzed leachate collected from different tillage systems for atrazine by EIA and GC/NPD. Guillard et al. (1999) used an EIA to compare the concentration of atrazine in leachate from plots receiving band or broadcast applications. 

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