Journal of Chromatography A - Volume 1070, Issues 1-2
, 8 April 2005, Pages 171-177
Determination of herbicides in mineral
and stagnant waters at ng/L levels using capillary electrophoresis
and UV detection combined with solid-phase extraction and sample
stacking
Javier Hernández-Borges (a), Francisco
J. García-Montelongo (a), Alejandro Cifuentes (b) and Miguel
Ángel Rodríguez-Delgado (a)
(a) Department of Analytical Chemistry, Nutrition and Food Science,
University of La Laguna, Avda. Astrofísico Fco. Sánchez
s/n, 38071 La Laguna, Santa Cruz de Tenerife, Spain
(b) Department of Food Analysis, Institute of Industrial Fermentations
(CSIC), Juan de la Cierva 3, 28006 Madrid, Spain
In this work, the combined use of solid-phase extraction (SPE)
and on-line preconcentration strategies as normal stacking mode
(NSM) and stacking with matrix removal (SWMR) for the ultrasensitive
and simultaneous capillary electrophoresis-ultraviolet analysis
(CE-UV) of five triazolopyrimidine sulfonanilide
pesticides (i.e., diclosulam, cloransulam-methyl,
flumetsulam, metosulam and florasulam) in different types
of water is investigated. An adequate separation electrolyte for
the separation and stacking of these pesticides was obtained,
considering also its compatibility with MS detection, which consisted
of 24 mM formic acid and 16 mM ammonium carbonate at
pH 6.4. It was observed that the use of this running buffer together
with the SWMR preconcentration method provided the best results
in terms of sensitivity (between 6.54 and 11.9 ?g/L) and
peak efficiency (up to 550 000 theoretical plates per meter,
NTP/m). When this on-line preconcentration procedure was combined
with an off-line sample preconcentration step as SPE using C18
cartridges, the selected herbicides could be detected in the ng/L
range. The optimized SPE-SWMR-CE-UV method was applied to the
determination of the selected group of pesticides in spiked and
non-spiked mineral and stagnant waters. Recoveries ranged between
55 and 110% and limits of detection between 131 and 342 ng/L.
This work shows the great possibilities of the combined use of
SPE-SWMR-CE-UV to overcome the sensitivity problems usually linked
to CE analysis.
• Note from FAN: Four
of the five triazolopyrimidine sulfonanilide
pesticides cited are fluorinated:
diclosulam, cloransulam-methyl,
flumetsulam,
and florasulam
Crop Protection - Volume 23, Issue 11 , November 2004,
Pages 1145-1149
Short communication
Using diclosulam in a weed control program
for peanut in South Texas
W. James Grichar (a), Brent A. Besler (a),
Kevin D. Brewer (a) and Vernon B. Langston (b)
(a) Texas Agricultural Experiment Station, 3507 Hwy 59E, Beeville,
TX 78102, USA
(b) Dow AgroSciences, The Woodlands,
TX 77382, USA
Field studies were conducted during the 1997 and 1998 growing
seasons to evaluate diclosulam alone and in combination with ethalfluralin
for Eclipta prostrata, Ipomoea lacunosa, Panicum texanum, and
Cyperus esculentus control. Diclosulam alone or in combination
with ethalfluralin-applied preplant incorporated (PPI), preemergence
(PRE), or postemergence (POST) at 0.009 to 0.024 kg ai/ha
provided at least 93% season-long Eclipta control. Ethalfluralin,
in combination with diclosulam-applied PPI at 0.016 or 0.024 kg ai/ha
controlled C. esculentus at least 82% season-long. Ethalfluralin
followed by diclosulam-applied POST at 0.016 or 0.024 kg/ha
controlled at least 90% Ipomoea season long, while ethalfluralin
followed by diclosulam-applied PPI or PRE at 0.024 kg/ha
controlled 81%. Ethalfluralin in combination with diclosulam at
0.016 kg/ha or ethalfluralin followed by diclosulam at 0.016
or 0.024 kg/ha applied POST controlled greater than 80% P.
texanum throughout the growing season. Diclosulam offers more
effective Eclipta control than the commerical standards now being
used.
• Note from FAN: Ethalfluralin
is a fluorinated pesticide.
http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11453764&dopt=Abstract
J Agric Food
Chem. 2001 Jul;49(7):3284-90.
Terrestrial
field dissipation of diclosulam at four sites in the United States.
Zabik
JM, van Wesenbeeck IJ, Peacock AL, Kennard LM, Roberts DW.
Dow
Agrosciences LLC, Building 306/A2, 9330
Zionsville Road, Indianapolis, Indiana 46268, USA. jmzabik@dowagro.com
The soil dissipation
of diclosulam was studied using 14C-labeled and nonradiolabeled
material in Mississippi, North Carolina, Georgia, and Illinois
between 1994 and 1997. The test substance was preemergence broadcast
applied at target rates of 35 and 37 g ai x ha(-1) for the 14C-labeled
and the nonradiolabeled studies, respectively. The degradation
of diclosulam was rapid with half-lives ranging from 13 to 43
days at the four sites. Rapid degradation rates and the increasing
sorption to soil over time resulted in low persistence and mobility
of this compound. Metabolite formation and dissipation in the
field reflected observations of photolysis, hydrolysis, and aerobic
soil metabolism studies in the laboratory. The rapid field dissipation
rates, metabolite formation patterns, and sorption characteristics
obtained in these field studies were consistent with the laboratory
data generated for diclosulam, and reflect the multiple concurrent
degradation mechanisms occurring in the field.
PMID: 11453764
[PubMed - indexed for MEDLINE]
http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11285917&dopt=Abstract
J Environ
Qual. 2001 Mar-Apr;30(2):553-60.
Measurement
and modeling of diclosulam runoff under the influence of
simulated severe rainfall.
van
Wesenbeeck IJ, Peacock AL, Havens PL.
Dow
AgroSciences,
Bldg. 306/A2, 9330 Zionsville Road, Indianapolis, IN 46268, USA.
iwesenbeeck@dowagro.com
A runoff study
was conducted near Tifton, GA to measure the losses of water,
sediment, and diclosulam (N-(2,6-dichlorophenyl)-5-ethoxy-7-fluoro-[1,2,4]triazolo-[1,5c]-pyrimidine-
2-sulfonamide), a new broadleaf herbicide, under a 50-mm-in-3-h
simulated rainfall event on three separate 0.05-ha plots. Results
of a runoff study were used to validate the Pesticide Root Zone
Model (PRZM, v. 3.12) using field-measured soil, chemical, and
weather inputs. The model-predicted edge-of-field diclosulam loading
was within 1% of the average observed diclosulam runoff from the
field study; however, partitioning between phases was not as well
predicted. The model was subsequently used with worst-case agricultural
practice inputs and a 41-yr weather record from Dublin, GA to
simulate edge-of-field runoff losses for the two most prevalent
soils (Tifton and Bibb) in the southeastern U.S. peanut (Arachis
hypogaea L.) market for 328 simulation years, and showed that
the 90th percentile runoff amounts, expressed as percent of applied
diclosulam, were 1.8, 0.6, and 5.2% for the runoff study plots
and Tifton and Bibb soils, respectively. The runoff study and
modeling indicated that more than 97% of the total diclosulam
runoff was transported off the field by water, with < 3% associated
with the sediment. Diclosulam losses due to runoff can be further
reduced by lower application rates, tillage and crop residue management
practices that reduce edge-of-field runoff, and conservation practices
such as vegetated filter strips.
PMID: 11285917
[PubMed - indexed for MEDLINE]
http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10995360&dopt=Abstract
J Agric Food
Chem. 2000 Sep;48(9):4335-40.
Aerobic
metabolism of diclosulam on U.S. and South American soils.
Yoder
RN, Huskin MA, Kennard LM, Zabik JM.
Global Environmental
Chemistry Laboratory, Dow
AgroSciences
LLC, 9330 Zionsville Road, Indianapolis, Indiana 46268, USA. rnyoder@dowagro.com
Degradation
of the sulfonanilide herbicide diclosulam was studied on nine
soils from three countries to determine the rates and products
of aerobic metabolism. Diclosulam was applied to four agricultural
soils from the United States, three from Argentina,
and two from Brazil at a rate of
0.1 ppm, equivalent to approximately twice the maximum field application
rate of 52 g of active ingredient/ha. U.S. and Brazilian soils
were incubated in the dark at 25 degrees C at 75% 0.3 bar moisture;
Argentinean soils were incubated in the dark at 20 degrees C and
45% moisture holding capacity. Samples were analyzed up to one
year after treatment. Two-compartment DT(50) and DT(90) values
averaged 28 +/- 12 and 190 +/- 91 days, respectively. Three soil
metabolites reached levels of >10% of applied in at least one
soil and were identified as the 5-hydroxy analogue of diclosulam
(5-OH-diclosulam), aminosulfonyl triazolopyrimidine (ASTP), and
the 8-chloro-5-hydroxy analogue of diclosulam (8-Cl-diclosulam).
The terminal products of diclosulam soil metabolism were mineralization
to CO(2) and bound soil residues. Apparent sorption coefficients
(K(d)) were determined on a subset of samples by extraction with
a 0. 01 M CaCl(2) solution followed by an acidified acetone extraction.
Initial sorption coefficients were similar to those obtained in
a batch equilibrium study and averaged 1.1 L/kg for the six soils
tested. K(d) coefficients for the metabolites, when available,
tended to be slightly lower than that for diclosulam. Sorptivity
of diclosulam and degradates increased with time.
PMID: 10995360
[PubMed - indexed for MEDLINE]
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