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In this study, the phosphidation of zirconium phosphate nanoparticles (ZrP) was pursued to create zirconium phosphide on the surface of ZrP (ZrP@P) by the calcination process. The morphology and structure of prepared ZrP and ZrP@P were characterized by different methods including XPS, SEM, XRD, and FT-IR. Deposited nanocomposite on a glassy carbon electrode (ZrP@P/GCE) showed boosted electrochemical properties towards oxidation of Asulam investigated by cyclic and differential pulse voltammetry techniques. After optimizing the variables affecting the ZrP@P/GCE response, the Asulam quantification was tested, and the linear range of 5–45 µg/L and detection limit of 0.16 µg/L were obtained. The phosphidation process increased the surface-active points and the active surface area of the ZrP facilitating the interaction of Asulam molecules with the GCE surface modified with ZrP@P. The ZrP@P/GCE accurately quantified Asulam in real samples such as tomato, lettuce, and cucumber with obtained recovery values of 96–113% and RSD ≤ 4.4%. This sensor offers a simple, low-cost, and convenient method to detect Asulam. [ABSTRACT FROM AUTHOR]

The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, the United Kingdom (France after Brexit), for the pesticide active substance asulam and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Regulation (EC) No 1107/2009 of the European Parliament and of the Council. The conclusions were reached on the basis of the evaluation of the representative use of asulam (variant evaluated asulam-sodium) as a herbicide on spinach and tulip, hyacinth and lily for bulb production. MRLs were assessed in spinach. The conclusions were updated with regard to the endocrine-disrupting properties following a mandate received from the European Commission in February 2019. In addition, the peer review also provided considerations on whether exposure to humans and the environment from the representative uses of asulam-sodium can be considered negligible, taking into account the European Commission’s draft guidance on this topic. The reliable endpoints, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified. An evaluation of data concerning the necessity of asulam-sodium as a herbicide to control a serious danger to plant health which cannot be contained by other available means, including non-chemical methods is also presented. [ABSTRACT FROM AUTHOR]

Abstract The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, the United Kingdom (France after Brexit), for the pesticide active substance asulam and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Regulation (EC) No 1107/2009 of the European Parliament and of the Council. The conclusions were reached on the basis of the evaluation of the representative use of asulam (variant evaluated asulam‐sodium) as a herbicide on spinach and tulip, hyacinth and lily for bulb production. MRLs were assessed in spinach. The conclusions were updated with regard to the endocrine‐disrupting properties following a mandate received from the European Commission in February 2019. In addition, the peer review also provided considerations on whether exposure to humans and the environment from the representative uses of asulam‐sodium can be considered negligible, taking into account the European Commission's draft guidance on this topic. The reliable endpoints, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified. An evaluation of data concerning the necessity of asulam‐sodium as a herbicide to control a serious danger to plant health which cannot be contained by other available means, including non‐chemical methods is also presented.

An analytical method based on LC-MS/MS was developed for the determination of asulam in livestock products. Asulam in livestock products was extracted with acetone. The crude extracts were defatted by acetonitrile and n-hexane partitioning. Cleanup was carried out using a combination of ethylene diamine-2V-propyl silylation silica gel (PSA) and octadecyl silylated silica gel (C18) mini columns with acidic condition. The sample solution was subjected to LC-MSZMS using an external solvent calibration curve. The average recovery (n = 5)of Asulam from four types of livestock products (bovine muscle, bovine fat, bovine liver and milk) spike at the maximum residue limits (MRLs) or at a uniform limit of 0.01 mg/kg was 92.7-98.7%, with a relative standard deviation of 3.1-11.6%. The limit of quantitation of the developed method was calculated to be 0.01 mg/kg. [ABSTRACT FROM AUTHOR]

Abstract The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, the United Kingdom, for the pesticide active substance asulam and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Regulation (EC) No 1107/2009 of the European Parliament and of the Council. The conclusions were reached on the basis of the evaluation of the representative use of asulam (variant evaluated asulam‐sodium) as a herbicide on spinach and tulip, hyacinth and lily for bulb production. MRLs were assessed in spinach. The reliable endpoints, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

The first approach of this research paper explores the simultaneous characterization and determination of the Asulam active ingredient and its associated nine impurities in bulk batch production by the gradient reverse-phase high-performance liquid chromatographic (RP-HPLC) method. The best separation from its potential impurities and reproducible method was achieved by selecting the Cosmosil C-18 (250 × 4.6 mm, 5 µm particle size) analytical column with a run time of 40 min. The pumping chromatographic mobile phase was composed of 0.1% formic acid in Milli-Q water (pH ~2.72) and methanol (80 + 20, v/v). An ambient column-oven temperature and UV detection at 260 nm were used. For this broad resolution, a gradient program was employed at a flow rate of 1.20 mL/min. All potential related substances in Asulam bulk manufacturing were ascertained by mass, proton nuclear magnetic resonance, and infrared spectroscopy. The developed HPLC method was validated with respect to linearity (25.64-151.83 mg/L for Asulam and 0.71-16.29, 1.02-12.26, 1.01-20.29, 0.60-10.01, 1.04-16.65, 0.94-22.47, 0.93-16.60, 1.00-12.45, 1.00-12.45, and 0.71-12.17 mg/L for Impurities A to I with a correlation coefficient 0.999 for Asulam and all the impurities), precision (RSD, % for active analyte Asulam and impurities were <2%), accuracy (percent recovery for Asulam at two levels ranged from 99.28 to 99.35%, and for Impurities A to I, it was 93.44 to 101.41%), and specificity. Hence, this simple and reliable HPLC method was able to determine the purity of Asulam active analyte and the level of impurities in bulk batch synthesis. By using this quantified procedure, five self-made production batches were analyzed simultaneously. [ABSTRACT FROM AUTHOR]

Inspired by the photoelectrochemical (PEC) properties of TiO 2 nanotubes arrays (TNA) and their application as a super vessel for immobilizing biomolecules, we constructed an inhibition-effect PEC biosensor for determination of asulam based on the in-situ generation of CdS quantum dots (QDs) on TNA using an enzymatic reaction. Horseradish peroxidase (HRP) enzyme was covalently assembled on the inner-wall of TNAs, which exhibited good electrochemical and catalytic properties. In the mixture solution containing H 2 O 2 , CdY and S 2 O 3 2- , HRP enzyme in TNAs catalyzed H 2 O 2 reduce S 2 O 3 2- to S 2- . The generated S 2- reacted with CdY to form CdS QDs in situ on the TNAs, improving the PEC performance of TNA under visible light irradiation. The photocurrent would decrease after addition of asulam due to its inhibitory effect towards HRP enzyme activity. Under the optimal experimental conditions, the constructed PEC TNA/HRP biosensor exhibited a satisfying linear range (0.02–2.0 ng mL −1 ), low limit of detection (4.1 pg mL −1 ) and good selectivity towards asulam determination, and has been successfully applied for the analysis of real environmental water samples with good accuracy of the recoveries ranged from 90% to 114%. [ABSTRACT FROM AUTHOR]

The conclusions of EFSA following the peer review of the initial risk assessments carried out by the competent authority of the rapporteur Member State, the United Kingdom, for the pesticide active substance asulam and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Regulation (EC) No 1107/2009 of the European Parliament and of the Council. The conclusions were reached on the basis of the evaluation of the representative use of asulam (variant evaluated asulam‐sodium) as a herbicide on spinach and tulip, hyacinth and lily for bulb production. MRLs were assessed in spinach. The reliable endpoints, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified. [ABSTRACT FROM AUTHOR]

This study reports 2 new simple derivatization-based dispersive liquid-liquid microextraction (DLLME) methods for spectrophotometric ultratrace determination of asulam and sulfide. 1-Naphthol (in the presence of nitrite) and N,N-diethyl-p-phenylenediamine (in the presence of Fe(III)) were used to derivatize asulam and sulfide, respectively. In the enrichment methods, the formed derivatives were preconcentrated into microdroplets of the in situ formed water insoluble ionic liquid (IL), 1-hexyl-3-methylimidazolium hexa uorophosphate. Monitoring was performed at 526 nm for asulam and at 664 nm for sulfide, after dissolution of the IL-rich phases into the basic ethanolic solution and ethanol for asulam and sulfide, respectively. Beer's law was obeyed in the ranges of 1.0-80.0 and 0.1-5.0 ng mL-1 for asulam and sufide, respectively. Limits of detection for asulam and sulfide determination by the DLLME methods were 0.18 and 0.019 ng mL-1, respectively. Various foreign cations, anions, organics, and pesticides were tested to evaluate the selectivity of the DLLME methods. The methods were successfully applied to the determination of asulam and sulfide in various environmental, wastewater, and urine samples. [ABSTRACT FROM AUTHOR]

There is a need for management strategies to control dominant perennial weeds and restore seminatural communities. We compared the effects of five weed control treatments on dense Pteridium aquilinum relative to an untreated experimental control over an 8-year period with the aim of restoring acid grassland. The weed control treatments tested were as follows: cutting and bruising, both twice and thrice annually, and herbicide treatment (asulam in year 1 followed by annual spot retreatment of all emergent fronds). Pteridium aquilinum performance and plant species composition were monitored. Data were analysed using Bayesian mixed-effect models and multivariate techniques. Cutting twice and thrice yearly and the asulam treatment all reduced frond density to zero; both bruising treatments were ineffective. The plant communities in the cut and asulam-treated plots showed differences from the untreated and bruised plots; the asulam-treated plots contained more ruderal species and the cut plots were more typical of acid grassland. Acid grassland recovery was fastest in the asulam-treated plots, but the cut plots caught up after approximately 5 years. There were two important conclusions. First, an intractable weed like P. aquilinum can be eradicated and a vegetation more suited for grazing can be achieved by the continuous application of some treatments over many years. Here, success was achieved by cutting twice/thrice annually, or by a single asulam application followed by annual spot spraying of all emergent fronds for 8 years. Second, bruising, a treatment favoured by some conservation organisations, did not work and cannot be recommended. The use of long-term, continuously applied treatments might be considered for all perennial weeds with large underground root/rhizome systems. [ABSTRACT FROM AUTHOR]

The article introduces a robust algorithm for the computation of minimum energy paths transiting along regions of near-to or degeneracy of adiabatic states. The method facilitates studies of excited state reactivity involving weakly avoided crossings and conical intersections. Based on the analysis of the change in the multiconfigurational wave function the algorithm takes the decision whether the optimization should continue following the same electronic state or switch to a different state. This algorithm helps to overcome convergence difficulties near degeneracies. The implementation in the MOLCAS quantum chemistry package is discussed. To demonstrate the utility of the proposed procedure four examples of application are provided: thymine, asulam, 1,2-dioxetane, and a three-double-bond model of the 11- cis-retinal protonated Schiff base. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

According to Article 12 of Regulation (EC) No 396/2005, the European Food Safety Authority (EFSA) has reviewed the Maximum Residue Levels (MRLs) currently established at European level for the pesticide active substance asulam. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of asulam are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses.

According to Article 12 of Regulation (EC) No 396/2005, the European Food Safety Authority (EFSA) has reviewed the Maximum Residue Levels (MRLs) currently established at European level for the pesticide active substance asulam. Considering that this active substance is no longer authorised within the European Union, that no MRLs are established by the Codex Alimentarius Commission, and that no import tolerances were notified to EFSA, residues of asulam are not expected to occur in any plant or animal commodity. Available data were also not sufficient to derive a residue definition or an LOQ for enforcement against potential illegal uses. [ABSTRACT FROM AUTHOR]

This work reports for the first time that nanostructured nickel (II) phthalocyanine/multiwalled carbon nanotubes composite supported on a basal plane pyrolytic electrode (NiPcNP/MWCNT-BPPGE) could potentially serve as a viable platform for the sensitive electrocatalytic detection of asulam pesticide at phosphate-buffered solution (pH 7.0 conditions). Comparative electron transfer dynamics, using ferrocyanide/ferricyanide as outer sphere redox probe, were examined and interpreted using the Davies–Compton theoretical framework dealing with voltammetry at spatially heterogeneous electrodes. The NiPcNP/MWCNT-BPPGE exhibits fast electron transport and excellent electrocatalytic behavior toward asulam, with an onset potential of about 150 mV lower than observed for the electrode without MWCNTs or bare BPPGE. Also, NiPcNP/MWCNT-BPPGE displayed good analytical performance for asulam, with a detection limit of 0.285 µM, a linear concentration range of 91–412 µM, and a sensitivity of 44.6 µA mM−1. [ABSTRACT FROM AUTHOR]

In this work, a new method is presented based on in-situ electropolymerization of dopamine (DA) monomer and asulam (ASL) as a target molecule to fabricate a molecularly imprinted polymer (MIP) on a glassy carbon electrode (GCE). In this regard, the most basic feature of the prepared sensor is that after template extraction the target molecule, cavities with the same size and stereochemical properties of it, remain on the imprinted polymer matrix. Accordingly, the developed sensing platform showed high selectivity and great sensitivity in ASL detection. The proposed method showed good linear range area from 0.5 to 20 pM with limit of detection of 0.17 pM. The influences of electropolymerization conditions e.g. incubation time, monomer to template concentration, cycle numbers and template extraction time were studied. Finally, it was applied for ASL detection in real samples, and the results were consistent with high-performance liquid chromatography obtained results. [Display omitted] • In this work a new sensor reported for ultratrace detection of Asulam based on a MIP. • GCE was modified with g-C 3 N 4 to enhance sensor performance. • DPV, CV and EIS techniques was used to record electrochemical response of sensor. • This sensor is made easy with high selectivity and good sensitivity. [ABSTRACT FROM AUTHOR]

Abstract: An efficient, sensitive and fast stopped-flow method has been developed to determine asulam in water, based on its inhibition effect on the horseradish peroxidase–luminol–hydrogen peroxide chemiluminescence reaction, (HRP–luminol–H2O2). Ultra fast data acquisition (0.20s) facilitates excellent selectivity because no interferences from concomitants in the matrix act in such short time scale. The precision as repeatability (expressed as relative standard deviation, n =10) was 0.4% at a 40pM level. The detection limit was 1.5pM (0.35ng/L) and 7.15pM in pure and raw water, respectively. The calibration data over the range 5–60pM present a correlation coefficient of r =0.9993. The proposed method has been applied to determine asulam in water samples by using solid-phase extraction (SPE). Mean recovery value was 98.1±2% at 50pM level. [Copyright &y& Elsevier]

The coastal heathlands of north-western Europe are endangered habitats of great conservation value. Invasion by bracken Pteridium aquilinum is a major challenge for conservation and restoration of these heathlands, including the under-studied northern regions. Today, the herbicide asulam is the most widely applied bracken control measure, but increasing focus on organic farming and nature conservation calls for alternative, preferably mechanical, approaches. In a 7-year replicated field experiment in western Norway, we investigated efficiencies of the four bracken control measures asulam, Gratil, annual cutting and biannual cutting, in restoring the characteristic heathland vegetation structure and species composition. We specifically tested herbicide effects on diversity and composition of non-target species. Effects of treatments over time were evaluated by repeated measures ANOVA, and for multivariate data, Principal Response Curves. Our results show that UK based control methods are largely applicable to bracken at its northern limit in the European heathland habitat. Asulam resulted in the fastest reduction in cover but cutting proved equally efficient long-term. Community compositions progressed towards desired heathland vegetation, but successional trajectories differed. Asulam had unintended effects on a number of heathland species not predictable by species characteristics or functional groups. Gratil failed to have any long-term effects. In summary, cutting is as efficient as herbicide application in reducing bracken, and more so in restoring northern heathland vegetation over time. [Copyright &y& Elsevier]

Questions: The objectives of this study were to assess the effect of Pteridium aquilinum (bracken) control treatments, at the national scale, and the impact of restoration practices, at the local scale, on P. aquilinum performance. Hypotheses: 1. Geographical location (locally between and within sites) affects the control of P. aquilinum through time. 2. Are the P. aquilinum control treatments successful at all sites, and if so which ones? 3. The treatments applied at the individual site level to restore vegetation influences the performance of P. aquilinum through time. Location: Four geographically distinct acid grassland and heathland sites infested with P. aquilinum across Great Britain. Methods: Six main-plot, bracken control treatments were applied to all sites with site-specific vegetation restoration treatments. Response variables (P. aquilinum cover, frond length and density) were monitored twice yearly, in June and August between 1993 and 2003. Results: Between- and within-site spatial variation was found, although impact is perhaps less than suggested from shorter-term data. Despite local variation all sites responded similarly to bracken control treatments; asulam treatment resulted in a rapid reduction in frond performance followed by a continued recovery taking approximately ten years to return to untreated values. Cutting treatments tended to have a slower impact at the start but an increasing one over time, especially cutting twice per year. Restoration treatments had a limited impact; the only significant effect in August was grass seeding on frond length at Sourhope. In June only, the plots where sheep were fenced out showed a significant reduction in P. aquilinum cover at Peak. Conclusions: Long-term control of Pteridium aquilinum at all sites and on all measures was best achieved using a continuous cutting treatment, preferably twice per year. [ABSTRACT FROM AUTHOR]

Abstract: This work describes the electrochemical properties of cobalt tetra-aminophthalocyanine (CoTAPc) complex electropolymerized at the surface of multi-walled carbon nanotube (MWCNT) abrasively immobilized onto a basal plane pyrolytic graphite electrode (BPPGE). The constructed electrode displayed excellent electrocatalytic behaviour towards the oxidation of the herbicide, asulam, as evidenced by the enhancement of the oxidation peak current (∼6 times) and the shift in the oxidation potential to lower values (by ∼120mV) in comparison with the bare BPPGE. The chronoamperometric detection of asulam which was carried out in 0.10M phosphate buffer (pH 7.0) at a fixed potential of 0.65V (versus Ag|AgCl) yielded excellent analytical parameters; a linear concentration range of 4.5–20μM, a sensitivity of 241×10−3 μA/μM, a detection limit of 1.15μM asulam (using the Y B +3σ criterion) and a response time of ∼2s. [Copyright &y& Elsevier]

This paper deals with a straightforward automated method for the determination of asulam in water based on the use of a flow manifold including three computer-controlled solenoid valves. The method involves irradiating on an aqueous solution of asulam in glycine buffer at pH 8.3 with UV light during 90 s, then follows the oxidation with potassium permanganate in a sulphuric medium and chemiluminescence-based detection of the resulting photoproducts. The limit of detection thus achieved is 40 μg l-1. The detector response is linear up to a 5 mg l-1 asulam concentration and the throughput is 30 samples h-1. In parallel tests, oxidation with alkaline ferricyanide was also assessed and the results compared (sensitivity, selectivity and reproducibility) with those from oxidation with potassium permanganate in acidic medium. The use of a flow based on solenoid valves results in substantial reagent savings and constitutes a further extension of clean chemistry procedures. To the authors’ knowledge, this is the first chemiluminescence-based determination of asulam and also the first based on multicommutation analysis. [Copyright &y& Elsevier]

A number of antibacterial drugs (antibiotics) like sulfonamides, tetracyclines and streptomycin are used for the treatment of bacterial diseases in beehives. Yet, the finding of sulfanilamide residues in some 15 Swiss honeys out of some 350 samples could not be explained by such apicultural practice. Bees occasionally collect nectar from meadows treated with the herbicide asulam. Such honey is not only contaminated by asulam, but also by its degradation product sulfanilamide. This is the first report that the use of a herbicide causes the appearance of residues of an antibacterial active metabolite belonging to the category of sulfonamide drugs in food. The relevance of this finding lies in the fact that the use of the herbicide asulam might cause unacceptable residue levels of sulfanilamide in a product for human consumption. [ABSTRACT FROM AUTHOR]

The effects of a pesticide mixture (asulam, fluazinam, lambda-cyhalothrin, and metamitron) on aquatic ecosystems were investigated in 20 outdoor aquatic microcosms. Ten of the microcosms simulated mesotrophic aquatic ecosystems dominated by submerged macrophytes (Elodea). The others simulated eutrophic ecosystems with a high Lemna surface coverage (Lemna). This paper describes the fate of the chemicals as well as their effects on the growth of Myriophyllum spicatum and the periphytic algal community. In the Elodea-dominated microcosms significant increase in the biomass and alterations of species composition of the periphytic algae were observed, but no effect on M. spicatum growth could be recorded in response to the treatment. The opposite was found in the Lemna-dominated microcosms, in which decreased growth of M. spicatum was observed but no alterations could be found in the periphytic community. In the Elodea-dominated microcosms the species composition of the periphytic algae diverged from that of the control following treatment with 0.5% spray drift emission of the label-recommended rate (5% for lambda-cyhalothrin), while reduced growth of M. spicatum in the Lemna-dominated microcosms was recorded at 2% drift (20% for lambda-cyhalothrin). This study shows that the structure of the ecosystem influences the final effect of pesticide exposure. [Copyright &y& Elsevier]

This feasibility study deals with the use of a wide bore (320 μm I.D.) capillary tube for the detection and identification of capillary zone electrophoresis (CZE) analytes by optical fiber-coupled diode array detection. A 250-μm mean effective pathlength of the detection cell with an inherently enhanced photon flux through the cell were significant contributors in reaching 0.2–1 μmol/l concentration detectabilities of the CZE analytes by this combination. Experiments with model analytes (p-sulfanilic, sorbic and naphthalene-2-sulfonic acids, tryptophan and asulam) revealed that spectral confirmations of their identities were still possible when their concentrations in the loaded samples (200 nl) were 1–5 μmol/l. Here, chemometry procedures (target transformation factor analysis, fixed size moving window-target transformation factor analysis, fixed size moving window-evolving factor analysis and orthogonal projection approach) employed in the data processing effectively contributed to reliable confirmation of the identities of the analytes also in critical situations (e.g. peak overlaps). The CZE separations were carried out in tandem-coupled columns of identical I.D. This made it possible to use, in the first column of the tandem, carrier electrolyte solutions that provide the desired separative effects, while in the second (detection) column the compositions of the carrier electrolyte solutions employed could reflect favorable conditions for obtaining spectral data. Mixtures containing model constituents at significantly differing concentrations and Maillard’s reaction products spiked with tryptophan enantiomers were employed in experiments aimed at assessing practical applicabilities and limits of the present approach to the analysis of samples characterized by complex ionic matrices. [Copyright &y& Elsevier]

The degradation of the herbicide asulam (4-amino-benzosulfonyl-methylcarbamate) was studied by excitation of iron (III) aquacomplexes in aqueous solutions at 365 nm as well as by exposition to solar light. Sulfanilamide was also studied as a model molecule. The initial step of asulam disappearance was shown to be due to the formation of hydroxyl radicals generated from the excitation of Fe(OH)2+, the most photoactive iron (III) monomeric species. However, when the iron (III) species was totally photoreduced to iron (II), the degradation of asulam in the presence of oxygen continued to completion. A photoreactivity of iron (II) species and/or iron (II) complexes under our experimental conditions was proposed. The experimental results indicate that the presence of iron (III), iron (II) and molecular oxygen is the condition for achieving the complete mineralization of the solution. The proposed photocatalytic cycle could provide an interesting tool for oxidations in the environment. [Copyright &y& Elsevier]

A simple end-column electrochemical detector was designed and attached to an available commercial capillary electrophoresis instrument with UV detection to detect different kind of herbicides and to determinate methyl-4-aminophenyl-sulfonylcarbamate (asulam) in water samples. The designed cell is very easy to assemble and disassemble in a short period of time; the working electrode positioning is also quickly achieved without micropositioners. The alignment between working electrode and capillary outlet was very reproducible for the all checked electrodes; the R.S.D. obtained was lower than 6.0% for 100 μm gap distance. In this mode, the non-electroactive and electroactive compounds could be detected by UV and electrochemical detection, respectively at the same time. The electrochemical determination of asulam using micellar electrokinetic capillary chromatography (MEKC) is the first time that is reported. In both detection systems, a linear range was obtained for asulam concentrations lower than 25.0 mg l−1, in boric acid 0.020 mol l−1 at pH 8.20 and containing 0.025 mol l−1 of sodium dodecyl sulfate, to obtain selectivity additional separation by the micellar distribution process. Under these conditions, an experimental detection limit of 0.4 mg l−1 was achieved. A new experimental scheme is also described for asulam determination in tap waters with a previous preconcentration step. Using both, UV and electrochemical detection, with a previous extraction procedure, the detection limits of asulam in tap water samples were of 1.0 and 0.8 μg l−1, respectively. [Copyright &y& Elsevier]

Fern spores were germinated, grown and exposed to different concentrations of asulam (the active ingredient of Asulox) in liquid culture. Gametophytes of Pteridium aquilinum [L. (Kuhn)] (bracken) were exposed to 100 g l-1 for 24 h at the following three stages: germination; during filamentous growth; and after transition had occurred. This treatment severely inhibited germination and killed photosynthetic gametophytes outright. Gametophytes of all species tested [Pteridium aquilinum, Cryptogramma crispa (L.) Hook and Dryopteris filix-mas (L.) Schott] varied in their responses to lower concentrations. This variation was in terms of the response of the gametophytes and the numbers of gametophytes showing each response. Some gametophytes suffered 100% cell mortality, but in others some cells died and some survived, while the remainder of the gametophytes suffered no cell mortality. The cells affected varied from gametophyte to gametophyte at the same dose and the proportions of gametophytes showing each response changed with concentration, mortality increasing with increasing concentration. Pteridium showed lower levels of mortality at each concentration than either of the other species. The bioassay system described provides a rapid laboratory-based method to screen for Asulox susceptibility of fern gametophytes in comparison with Pteridium. [ABSTRACT FROM AUTHOR]

Bracken is often perceived as a widespread and increasing land management problem. The pollen record of a wide range of sites in Great Britain suggests that the current abundance of bracken is less than or, at worst, equivalent to maximum historical levels. Recently gathered data also suggest that bracken cover is declining. Results of risk assessments of land use change, and experimental and modelling investigations into the effects of climate change are synthesized. This synthesis suggests that there is the potential for increased bracken dominance in northern Britain, spread into new areas at high altitudes, and possible spread into areas with reduced grazing. However, this must be set against any changes in the extent of other vegetation types at the expense of bracken. There is now a long history of bracken control, both in Great Britain and globally. Conventional methods of control (cutting, asulam application) are well understood, but many control attempts do not result in long-term success, as control is often not followed by aftercare. Bracken control is just one part of the process to ensure a sustainable use of resources and to maintain biodiversity. A coherent strategy for bracken control is put forward, a necessary part of which includes the restoration of vegetation and subsequent land management which takes into account an understanding of bracken ecology. [ABSTRACT FROM AUTHOR]

The effect of three bracken control treatments on the rhizome system of bracken (Pteridum aquilinum (L.) Kuhn) at Cavenham and Weeting Healths in Breckland was assessed. Control treatments included cutting once and twice yearly between 1978 and 1990, and spraying the herbicide asulam at the recommended rate (4.4 kg a.i. ha-1) in 1978 and 1985. In addition, the effect of continuous treatment was compared with plots in which bracken control ceased after 6 years. The effects on rhizome biomass and length, numbers of active and dormant buds, and starch and soluble carbohydrate concentrations were measured. Cutting twice yearly was the most effective treatment, but rhizomes persisted even after 12 years of continous treatment. Cutting once yearly and applying asulam gave intermediate reductions in all rhizone variables. Where bracken control ceased there was a relatively rapid increase in all measures of rhizome performance. At Cavenham Heath, remission for 4 years increased the starch levels in rhizomes, and after 6 years increased all rhizome measures. Weeting Heath all measures were significantly increased 5 years after control treatments ceased. Regression analyses showed that the majority of the variation in summer frond performance (0.39–0.75) could be explained by rhizome biomass. At both sites amounts of starch and carbohydrate in the rhizome biomass. At both sites amounts of starch and carbohydrate in the rhizome, and at Weeting the above-ground grass biomass and total bud number, improved the fit of some equations. Some earlier published data for Weeting Health were used to estimate rates of rhizome depletion and recovery. Extrapolation from these results suggested that it would take (a) a further 8–34 years to eradicate bracken depending on treatment, and (b) between 9 years (for the cut once yearly and asulam treatments) and 62 years (for the cut twice yearly treatment) for the bracken rhizome system) to recover its starting biomass. Moreover, a large frond biomass would occur before the rhizome system recovered completely, The rates obtained from Weeting were used to predict the outcome of the Cavenham experiment and a reasonable fit was achieved. [ABSTRACT FROM AUTHOR]

The uptake and translocation of [14C]asulam (methyl 4-aminophenyl-sulphonylcarbamate), [14C]aminotriazole (1-H-1,2,4-triazol-3-ylamine) and [14C]glyphosate (N-(phosphonomethyl)glycine) were assessed in Equisetum arvense L. (field horsetail), a weed of mainly horticultural situations. Under controlled-environment conditions, 21°C day/18°C night and 70% r. h., the test herbicides were applied to 2-month-old and 2-year-old plants. Seven days following the application of 0.07-0.09 °Ci (1.14mg) of the test herbicides to young E. arvense, the accumulation of 14C-label (as percentage of applied radioactivity) in the treated shoots, untreated apical and basal shoots was as follows: [14C]asulam, 13.2, 0.18 and 1.02%; [14C] aminotriazole, 67.2, 3.65 and 1-91%; [14C]glyphosate, 35.9, 0.06 and 0.11%. The equivalent mean values for the accumulation of 14C-label in 2-year-old E. arvense were [14C]asulam, 12.0, 1-15 and 1.74%; [14C]aminotriazole, 58.6, 9.44 and 4.12%; [14C]glyphosate, 33.1, 0.79 and 2.32%. In the latter experiment, test plants received 0.25-0.30 °Ci (4mg) of herbicide, they were assessed after a 14-day period and the experiment was carried out at 3-week intervals between 2 June and 25 August on outdoor-grown plants. Irrespective of test herbicide or time of application, very low levels of 14C-label accumulated in the rhizome system. Only 0.2% of the applied radioactivity was recovered in 2-year-old plants and 0.4% in 2-month-old plants. In the young plants [14C]asulam accumulated greater amounts and concentrations of 14C-label in the rhizome apices and nodes than [14C]aminotriazole or [14C]glyphosate treatments. Inadequate control of E. arvense under field conditions may be due to limited basipetal translocation and accumulation of the test herbicides in the rhizome apices and nodes. [ABSTRACT FROM AUTHOR]

An analytical method based on LC-MS/MS was developed for the determination of asulam in livestock products. Asulam in livestock products was extracted with acetone. The crude extracts were defatted by acetonitrile and n-hexane partitioning. Cleanup was carried out using a combination of ethylene diamine-N-propyl silylation silica gel (PSA) and octadecyl silylated silica gel (C 18 ) mini columns with acidic condition. The sample solution was subjected to LC-MS/MS using an external solvent calibration curve. The average recovery (n=5) of Asulam from four types of livestock products (bovine muscle, bovine fat, bovine liver and milk) spike at the maximum residue limits (MRLs) or at a uniform limit of 0.01 mg/kg was 92.7-98.7%, with a relative standard deviation of 3.1-11.6%. The limit of quantitation of the developed method was calculated to be 0.01 mg/kg.