SEARCH · Search PubMed

Results for “Simazine”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources

PubMed2000

Selective trace enrichment of chlorotriazine pesticides from natural waters and sediment samples using terbuthylazine molecularly imprinted polymers

Two molecularly imprinted polymers were synthesized using either dichloromethane or toluene as the porogen and terbuthylazine as the template and were used as solid-phase extraction cartridges for the enrichment of six chlorotriazines (deisopropylatrazine, deethylatrazine, simazine, atrazine, propazine, and terbuthylazine) in natural water and sediment samples. The extracted samples were analyzed by liquid chromatography/diode array detection (LC/DAD). Several washing solvents, as well as different volumes, were tested for their ability to remove the matrix components nonspecifically adsorbed on the sorbents. This cleanup step was shown to be of prime importance to the successful extraction of the pesticides from the aqueous samples. The optimal analytical conditions were obtained when the MIP imprinted using dichloromethane was the sorbent, 2 mL of dichloromethane was used in the washing step, and the preconcentrated analytes were eluted with 8 mL of methanol. The recoveries were higher than 80% for all the chlorotriazines except for propazine (53%) when 50- or 100-mL groundwater samples, spiked at 1 microg/L level, were analyzed. The limits of detection varied from 0.05 to 0.2 microg/L when preconcentrating a 100-mL groundwater sample. Natural sediment samples from the Ebre Delta area (Tarragona, Spain) containing atrazine and deethylatrazine were Soxhlet extracted and analyzed by the methodology developed in this work. No significant interferences from the sample matrix were noticed, thus indicating good selectivity of the MIP sorbents used.

Journal Article↗

PubMed1991

Solid-phase extraction of pesticides from water: possible interferences from dissolved organic material.

A multiresidue analysis for trifluralin, simazine, atrazine, propazine, diazinon, parathion-methyl, alachlor, malathion, parathion, chlorpyrifos, pendimethalin, methidathion, and DEF in water that utilizes liquid-solid extraction (LSE) with octadecyl-bonded silica cartridges (C18BSCs) followed by gas chromatography/mass spectrometric analysis was developed. Recoveries of most pesticides were greater than 80% with C18BSCs from fortified water at concentration levels from about 1 to 500 ppb. Recoveries with C18BSCs, from an optically adjusted humic acid solution (10 ppm dissolved organic carbon) made to simulate a natural water with a high dissolved organic content, ranged from 29 to 153% and in general were lower than recoveries obtained from pure water. 14C-Labeled diazinon and parathion were recovered from the humic acid solution at levels of 57 and 68%, respectively, with C18BSCs; the remainder of the labeled pesticides was found in the cartridge eluents. Partition coefficients with human acid were calculated based on recovery of 14C-labeled pesticides from the C18BSCs.

Indicators and Reagents↗

PubMed2001

Evaluation of a multidimensional solid-phase extraction platform for highly selective on-line cleanup and high-throughput LC-MS analysis of triazines in river water samples using molecularly imprinted polymers.

A novel highly selective sample cleanup procedure based on the use of molecularly imprinted polymers (MIPs) as solid-phase extraction materials has been evaluated with respect to its applicability and routine use in environmental analysis. The method comprises the combination of a restricted access material (RAM) and a MIP allowing a selective sample preparation to be achieved in the online mode. This combination is called the size-selective sample separation and solvent switch (six-SPE). The RAM column combines size exclusion and adsorption chromatography, reducing the concentration of matrix molecules by a cutoff of 15 kDa. The MIP column selectively retains the triazine analytes whereas the residual matrix is not retained and separated completely. Thus, the automated RAM-MIP is capable of excluding all matrix and nontarget compounds. The cleaned and enriched extract is subsequently eluted to an HPLC column and analyzed by LC-MS. A complete on-line analysis cycle including multidimensional solid-phase extraction, separation, and detection takes less than 15 min. Terbuthylazine, atrazine, propazine, simazine, ametryn, prometryn, irgarol, and also the metabolites deethylatrazine and deisopropylatrazine can be determined without any matrix interferences, e.g., by humic acids. The whole setup is fully automated and may be continuously operated. Nonspecific interactions with the polymer are below 1% in all cases. The accuracy of the LC-MIP-LC-MS system was controlled using a certified reference material (Aquacheck). The applicability of the method to the cleanup of real samples was demonstrated by injection of contaminated river water samples. The stability of different polymers was tested by consecutive injections, and it was shown that the performance of the materials did not vary even after more than 300 enrichment and desorption cycles.

Journal Article↗

PubMed1990

Enzyme-linked immunosorbent assay compared with gas chromatography/mass spectrometry for the determination of triazine herbicides in water.

An enzyme-linked immunosorbent assay (ELISA) was compared to a gas chromatography/mass spectrometry (GC/MS) procedure for the analysis of triazine herbicides and their metabolites in surface water and groundwater. Apparent recoveries from natural water and spiked water by both methods were comparable at 0.2-2 micrograms/L. Solid-phase extraction (SPE) was examined also, and recoveries were determined for a suite of triazine herbicides. A significant correlation was obtained between the ELISA and GC/MS method for natural water samples that were extracted by SPE. Because ELISA was developed with an atrazine-like compound as the hapten with conjugation at the 2-position, it was selective for triazines that contained both ethyl and isopropyl side chains. Concentrations for 50% inhibition (IC50) were as follows: atrazine, 0.4 microgram/L; ametryne, 0.45 microgram/L; prometryn and propazine, 0.5 microgram/L; prometon, 0.7 microgram/L; simazine and terbutryn, 2.5 micrograms/L; hydroxyatrazine, 28 micrograms/L; deethylatrazine and deisopropylatrazine, 30 micrograms/L; cyanazine, 40 micrograms/L; didealkylatrazine had no response. The combination of screening analysis by ELISA, which requires no sample preparation and works on 160 microL of sample, and confirmation by GC/MS was designed for rapid, inexpensive analysis of triazine herbicides in water.

Enzyme-Linked Immunosorbent Assay↗

PubMed2004

Use of quadrupole time-of-flight mass spectrometry in environmental analysis: elucidation of transformation products of triazine herbicides in water after UV exposure.

The high resolution and exact mass capabilities of hybrid quadrupole time-of-flight (QTOF) mass spectrometry can provide an ultimate confirmation in target analysis mode and aid in discovery and elucidation of unknown analytes. In this paper, the latter approach has been applied to study the transformation products of selected pesticides (terbuthylazine, simazine, terbutryn, terbumeton) in environmental waters. Additionally, the usefulness of software modules, originally designed for drug metabolism discovery, has been tested. Different environmental waters spiked at a 0.5 microg/mL level have been irradiated with a mercury lamp for 7 days, sampling 3-mL aliquots every approximately 12 h. After centrifugation, 50 microL was directly injected in an LC-ESI-QTOF system. The high sensitivity in full-scan mode allowed us to elucidate minor metabolites even below 2% of the total peak area. The mass errors observed in almost every case fell below 2 mDa, allowing assignment of a highly probable empirical formula. Besides, the MS/MS capability of this tandem instrument was very useful for differentiation between isomeric transformation products. This work shows that hyphenated LC-QTOF is a powerful approach for the rapid screening and confirmation of unknown pesticide transformation products in environmental water.

Journal Article↗

PubMed1997

Baker's yeast biomass (Saccharomyces cerevisae) for selective on-line trace enrichment and liquid chromatography of polar pesticides in water.

Baker's yeast cells (Saccharomices cerevisae) were successfully immobilized onto silica gel and used in the on-line isolation and trace enrichment of desisopropylatrazine, desethylatrazine, hydroxyatrazine, simazine, cyanazine, atrazine, carbaryl, propanil, linuron, and fenamiphos. Since humic and fulvic acids were not coextracted, no cleanup was necessary. The pesticides were spiked at 0.1-1 microgram L-1 in tap water, groundwater, and seawater and were preconcentrated using on-line solid-phase extraction into a yeast immobilized on silica gel precolumn followed by liquid chromatography with diode array detection. All the variables that affect the enrichment step, such as amount of yeast immobilized, dimensions of the precolumn, sample pH, and preconcentration flow rate, were optimized. The degree of selectivity was evaluated by comparing the chromatograms obtained after on-line sample preconcentration on the yeast precolumn with those obtained by on-line solid-phase extraction using a precolumn filled with C18 material. The relative standard deviation for the whole procedure in the determination of the selected pesticides at the 0.3 microgram L-1 concentration level ranged from 1 to 9%, depending on the pesticide and the type of water. Detection limits within the range 0.01-0.5 microgram L-1 were obtained by percolating only 25 mL of water sample without any additional cleanup step.

Biomass↗

PubMed2004

Characterizing dependence of pesticide load in surface water on precipitation and pesticide use for the Sacramento River watershed.

Transport of pesticides by surface runoff during rainfall events is a major process contributing to pesticide contamination in rivers. This study presents an empirical regression model that relates pesticide loading over time in the Sacramento River with the precipitation and pesticide use in the Sacramento River watershed. The model closely simulated loading dynamics of diazinon, simazine, and diuron during 1991-1994 and 1997-2000 winter storm seasons. The coefficients of determination for regression ranged from 0.168 to 0.907, all were significant at <0.001. The results of this study provide strong evidence that precipitation and pesticide use are the two major environmental variables dictating the dynamics of pesticide transport into surface water in a watershed. The capability of the statistical model to provide time-series estimates on pesticide loading in rivers is unique and may be useful fortotal maximum daily load (TMDL) assessments.

Agriculture↗

PubMed2005

Sol-gel immunosorbents doped with polyclonal antibodies for the selective extraction of malathion and triazines from aqueous samples.

Sol-gel immunosorbents (IS) prepared by encapsulation of polyclonal antibodies in silica were packed in cartridges and evaluated for selective immunoaffinity extraction (IAE) of malathion and triazines from aqueous samples. Encapsulated atrazine antibodies highly cross-reacted with simazine and propazine but did not recognize prometon and prometryn. No cross-reactivity of malathion antibodies was observed with the closely related metabolites oxomalathion and isomalathion. Mean IS binding capacities per milligram of entrapped antibody were 0.33 nmol of malathion and 0.47 nmol of atrazine (approximately 100 ng each). This capacity remained constant for at least 10 weeks, and the cartridge reusability was excellent (>60 IAE runs); also, high preconcentration factors were feasible because the breakthrough of analytes from IS cartridges did not occur up to the 250 mL sample volumes, provided that the capacity was not surpassed. Simple and rapid methods for determination of malathion or three triazines in surface water were developed using off-line IAE and HPLC-UV. The application to 50 mL dam water samples spiked at approximately 1 ng/mL of pesticides resulted in recoveries of approximately 90% and RSD < 5% (n=7). LODs for this sample volume (direct injection of IS eluates) were in the range of 0.15-0.50 ng/mL. Lower LODs (0.03-0.1 ng/mL) were achieved by online analysis of whole eluates previously loaded in RP precolumns.

Antibodies↗

PubMed2005

ELISA as an affordable methodology for monitoring groundwater contamination by pesticides in low-income countries.

The traditional instrumental technology for pesticide residue analysis is too expensive and labor-intense to meet the regional needs concerning environmental monitoring. ELISA methodology was used for a pilot scale study of groundwater quality in an agricultural region a few kilometers southwest of Montevideo, the capital city of Uruguay. The study spanned 2 years and examined concentrations (detection limits are given in [ppb]) of two triazine herbicides (simazine [0.3] and atrazine [0.4]) and the carbamate insecticide carbaryl [10] and its major metabolite 1-naphthol [17]. In general, pesticide concentrations were below detection limits in the samples tested and in all cases were well below the maximum contaminant levels set by the U.S. EPA. 1-Naphthol was detected frequently by ELISA, but the assay may have tended to systematically overestimate this analyte. To our knowledge, this is the first study of its type in Uruguay and perhaps the first systematic approach to monitoring for organic pesticides in groundwater water sources in the temperate region of South America.

Agriculture↗

PubMed2006

Including mixtures in the determination of water quality criteria for herbicides in surface water.

Monitoring programs throughout America and Europe have demonstrated the common occurrence of herbicides in surface water. Nevertheless, mixtures are rarely taken into account in water quality regulation. Taking mixtures into account is only feasible if the water quality criteria (WQC) of the single compounds are derived by a common and consistent methodology, which overcomes differences in data quality without settling on the lowest common denominator but making best use of all available data. In this paper, we present a method of defining a risk quotient for mixtures of herbicides with a similar mode of action (RQm). Consistent and comparable WQC are defined for single herbicides as a basis for the calculation of the RQm. Derived from the concentration addition model, the RQm can be expressed as the sum of the ratios of the measured environmental concentration and the WQC for each herbicide. The RQm should be less than one to ensure an acceptable risk to aquatic life. This approach has the advantage of being easy to calculate and communicate, and is proposed as a replacement for the current limit of 0.1 microg/L for herbicides in Switzerland. We illustrate the proposed approach on the example of five commonly applied herbicides (atrazine, simazine, terbuthylazine, isoproturon, and diuron). Their risk profile, i.e., the RQm as a function of time for one exemplary river, clearly shows that the single compounds rarely exceeded their individual WQC. However, the contribution of peaks of different seasonally applied herbicides, whose application periods partially overlap, together with the continuously emitted herbicides from nonagricultural use, results in the exceedance of the RQm threshold value of one upon several occasions.

Herbicides↗

PubMed2002

Herbicide and insecticide loadings from the Susquehanna River to the northern Chesapeake Bay.

The Susquehanna River watershed has a large drainage area (71200 km(2)) containing heavy agricultural land usage. The river provides approximately half the total freshwater input to the Chesapeake Bay. Water samples were collected at Conowingo Dam near the mouth of the river every 9 days from February 1997 through March 1998. Atrazine, its transformation product 6-amino-2-chloro-4-(isopropylamino)-s-triazine (CIAT), and metolachlor were found in the highest concentrations with maximums of 500, 150, and 330 ng/L, respectively. The annual mass loads for atrazine, CIAT, metolachlor, simazine, and 6-amino-2-chloro-4-(ethylamino)-s-triazine (CEAT) from the Susquehanna River to the Chesapeake Bay were 1600, 1600, 1100, 820, and 720 kg/year, respectively. Annual loadings of insecticides and organochlorine compounds ranged from 2.8 kg/year for alpha-HCH to 34 kg/year for diazinon. Strong correlations between loading data from this and previous studies and total annual water discharge through the dam were used to estimate total metolachlor and atrazine loads (12400 and 9950 kg, respectively) to the northern Chesapeake Bay from 1992 to 1997.

Acetamides↗

PubMed2002

Determination of triazine and chloroacetanilide herbicides in soils by microwave-assisted extraction (MAE) coupled to gas chromatographic analysis with either GC-NPD or GC-MS.

A simple and rapid method based on microwave-assisted extraction (MAE) coupled to gas chromatographic analysis was developed for the analysis of triazine (atrazine, cyanazine, metribuzine, simazine and deethylatrazine, and deisopropylatrazine) and chloroacetanilide (acetochlor, alachlor, and metolachlor) herbicide residues in soils. Soil samples are processed by MAE for 5 min at 80 degrees C in the presence of acetonitrile (20 mL/sample). Mean recovery values of most solutes are >80% in the 10 to 500 microg/kg fortification range with respective RSDs (relative standard deviations) < 20%. The limits of quantification (LOQ) and limits of detection (LOD) are 10 and 1 to 5 microg/kg, respectively. The method was validated with two types of soils containing 1.5 and 3.0% organic matter content, respectively; no statistically significant differences were found between solute recovery values from the two types of soils. The solute mean recovery values from freshly spiked (24 h aging) and spiked samples stored refrigerated for one week before processed were also not statistically different. Residue levels determined in field weathered soils were higher when soils were processed by MAE than with a comparison method based on flask-shaking of soil suspensions overnight. Extracts were analyzed by a gas chromatographic system equipped either with a thermionic (GC-NPD) or a mass spectrometric detector (GC-MS).

Acetamides↗

PubMed2005

Adsorption of pesticides from water by functionalized organobentonites.

Replacement of natural inorganic cations of clay minerals with organic cations has been proposed as a strategy to improve the adsorptive capacity of clay minerals for organic compounds, including pesticides. The organic cations most commonly used for this purpose have been quaternary ammonium ions containing alkyl or aryl chains without specific functional groups. In this work, we evaluated the ability of two bentonites (SWy-2 and SAz-1) exchanged with four natural organic cations containing diverse functional groups (L-carnitine, L-cysteine ethyl ester, L-cystine dimethyl ester, and thiamine) as adsorbents of pesticides varying in their chemical structures (simazine, hexazinone, triadimefon, alachlor, carbaryl, and imazethapyr). For comparison purposes, the adsorptive properties of two "classical" organobentonites, hexadecyltrimethylammonium- and phenyltrimethylammonium-exchanged bentonites, were also determined. Most organobentonites displayed higher affinity for the pesticides than the untreated bentonites, but the improvement in adsorption capacity varied depending on the characteristics of the pesticide and the interlayer organic cation. Triadimefon, carbaryl, and imazethapyr displayed the highest affinity for carnitine (K(f) = 229-2377)-, thiamine (K(f) = 83-354)-, and cystine (K(f) = 96-100)-treated bentonites, respectively, whereas alachlor was adsorbed similarly by all organobentonites. In general, pesticide adsorption-desorption hysteresis was greater for adsorbents with the highest adsorption capacities. The results demonstrate that selective modification of smectitic clay minerals with natural organic cations containing appropriate functional groups can be a useful strategy to improve their performance for the removal of specific pesticides from the environment.

Adsorption↗

PubMed1998

Development of an enzyme-linked immunosorbent assay for atrazine mercapturic acid in human urine.

Improved assessments of human exposure to electrophilic chemicals require rapid and inexpensive analytical techniques that can detect specific urinary metabolites at low levels as needed for epidemiological screenings of large populations. The first aim of this study has been to apply rational hapten design strategies to develop a more sensitive and selective enzyme-linked immunosorbent assay for atrazine mercapturic acid. Polyclonal sheep antiserum was generated against an improved hapten, numerous coating antigen chemistries were evaluated, and assay conditions were optimized. An assay was developed with an IC50 of 0.08 +/- 0.02 micrograms/L (K approximately with 10(-)10 M) for atrazine mercapturic acid. The assay exhibited greatest recognition of atrazine mercapturic acid relative to other known urinary metabolites of atrazine as well as other triazine herbicides. The assay was surprisingly selective to atrazine mercapturic acid over the structurally similar simazine mercapturic acid. Urine samples presented matrix effects due in part to the nonspecific effects of urinary salts, but 4-fold dilution of urine achieved an overall method limit of quantitation of 0.3 micrograms/L. Solid-phase extraction strategies were also developed in an attempt to increase the sensitivity of the overall method. However, a weak positive assay response was present in the solid-phase extracts of unspiked urines, resulting in accurate recovery of atrazine mercapturic acid at microgram/L.

Acetylcysteine↗

PubMed2004

Ban on triazine herbicides likely to reduce but not negate relative benefits of GMHT maize cropping.

The UK Farm-Scale Evaluations (FSE) compared the effects on biodiversity of management of genetically modified herbicide-tolerant (GMHT) spring-sown crops with conventional crop management. The FSE reported larger weed abundance under GMHT management for fodder maize, one of three crops studied. Increased seed production may be important for the long-term persistence of these arable weeds and may benefit invertebrates, small mammals and seed-eating birds. In three-quarters of FSE maize fields, growers used atrazine on the conventionally managed half, reflecting contemporary commercial practice. Withdrawal of the triazine herbicides atrazine, simazine and cyanazine from approved lists of EU chemicals could therefore reduce or even reverse the reported benefits of GMHT maize. Here we analyse effects of applications of triazine herbicides in conventional maize regimes on key indicators, using FSE data. Weed abundances were decreased greatly relative to all other regimes whenever atrazine was applied before weeds emerged. Here, we forecast weed abundances in post-triazine herbicide regimes. We predict weed abundances under future conventional herbicide management to be considerably larger than that for atrazine used before weeds emerged, but still smaller than for the four FSE sites analysed that used only non-triazine herbicides. Our overall conclusion is that the comparative benefits for arable biodiversity of GMHT maize cropping would be reduced, but not eliminated, by the withdrawal of triazines from conventional maize cropping.

Atrazine↗

PubMed2004

Seasonal pesticide use in a rural community on the US/Mexico border.

An environmental measurement and correlation study of infant and toddler exposure to pesticides was carried out in a colonia south of the city of Laredo, Texas. As part of the study, homes were visited during the late spring or summer, and during the winter of 2000-2001. At each visit, families reported on their use of pesticides in and around the home and floor wipe samples were collected and analyzed for 14 organophosphate and triazine pesticides. Selection of homes was based on the presence of infants and toddlers. A total of 27 homes participated in both seasonal visits. The interval between visits was 6 +/- 1.4 months. Univariate and multivariate nonparametric analyses were carried out using SPSS statistical software. Pesticide use within the home was more often reported than outside use and showed seasonal variation in use patterns. Indoor use was primarily associated with ants and cockroaches, and secondarily with rodents. The primary room treated was the kitchen, and the primary structures treated were the floors, lower walls, and dish cupboards. Seasonal variations were not found in the use of pesticides used outside the home and outdoor use was primarily associated with ant control. Based on parent reports, most pesticides used in the homes were pyrethroids. Several of the pesticides measured in floor wipe samples, Azinphos methyl, Fonofos, and Simazine, also showed seasonal variations. However, these pesticides are used in agriculture and were not associated with reported house and yard use patterns.

Child↗

PubMed2003

Assessment of the cross-reactivity and binding sites characterisation of a propazine-imprinted polymer using the Langmuir-Freundlich isotherm.

In this paper, the Langmuir-Freundlich isotherm is used to model the interaction of several triazines (desethylatrazine, desisopropylatrazine, simazine, atrazine, propazine and prometryn) with a propazine-imprinted polymer and to explain the observed cross-reactivity. Different rebinding experiments (each herbicide alone or all together in a mixture) were carried out and the experimental binding isotherms were fitted to the Langmuir-Freundlich isotherm. The fitting coefficients obtained (total number of binding sites, mean binding affinity and heterogeneity index) allowed the description of the kind of binding sites present in the imprinted polymer under study. It was concluded that the recognition mechanism was mainly governed by the molecular size although slight differences in the molecular structure may also play an important role. The obtained results suggest that the use of this new methodology can open new pathways for understanding how molecular recognition in imprinted polymers takes place.

Journal Article↗

PubMed1989

WHO drinking water quality guidelines for selected herbicides.

Following the successful introduction of its Guidelines for Drinking-Water Quality in 1984, the WHO Regional Office for Europe was approached by the Government of Italy to develop, as a matter of urgency, recommendations for guidelines levels of certain herbicides found in drinking water supplies. Realizing the extent of the problem, the Regional Office for Europe organized two consultations to develop drinking water quality guidelines for the following 11 herbicides most commonly used in Italy: alachlor, metolachlor, pyridate, atrazine, molinate, simazine, bentazon, pendimethalin, trifluralin, MCPA and propanil. The presence of these and other herbicides in ground and surface water has been reported in several countries. Although the main purpose of these guidelines is to provide guidance to the Government of Italy in making risk management decisions, the information given was also intended to assist the other countries of the European Region in setting standards or in developing alternative control procedures where the implementation of standards is not feasible. The purpose of this paper is to review the process of health risk assessment used in the development of the WHO drinking water quality guidelines for selected herbicides. It will also reveal the major dilemmas and concerns expressed by the participating experts during the process of scientific deliberations, in the interests of understanding the complex issues involved in reaching the bare figures of the recommended guidelines.

Herbicides↗