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41.
The monitoring of pesticide residues in water sources is essential because of their increased worldwide demand in agriculture and their subsequent detection in waters. Pesticide residues in water matrices are traditionally determined by multiresidue methodologies based on chromatography coupled to mass spectrometry. However, for quaternary ammonium pesticide residues, as highly polar compounds, the chromatographic approach frequently fails, requiring modifications in the separation method, or even an alternative technique for analyte quantification. Therefore, to solve this analytical limitation for these residues, several authors proposed unusual methodologies, such as those based on spectroscopic or electroanalytical approaches. This review intends to offer an overview of the analysis of quaternary ammonium pesticide residues in different water sources, focusing on advances in sample preparation before chromatographic separations and alternative analytical techniques, such as spectroscopy and electroanalytical methods. 相似文献
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Lopes IC De Souza D Machado SA Tanaka AA 《Analytical and bioanalytical chemistry》2007,388(8):1907-1914
This work describes the application of an ordinary pyrolitic graphite electrode modified by metallophthalocyanine allied to
square wave voltammetry for the study of the electrochemical behavior of the herbicide paraquat and the development of a method
for its analytical determination in natural water samples. Preliminary experiments indicated that the best responses, considering
the intensities of the current and voltammetric profile for the paraquat reduction process, were obtained when the electrode
modified by cobalt phthalocyanine was employed, which had a better catalytic activity as a result of this modification compared
with that for an unmodified electrode and electrodes modified by iron, manganese and the acid form of the phthalocyanines.
Studies of the concentration of cobalt phthalocyanine and the adsorption time showed that 1.0 × 10−4 mol L−1 cobalt phthalocyanine with an adsorption time of 10 min was sufficient to obtain reliability and stability of modification
for employment in the development of the electroanalytical procedure for paraquat determination in natural water samples.
The variation in pH of a 0.10 mol L−1 Britton–Robinson buffer solution and the square wave parameters indicated that the best conditions to reduce paraquat were
pH 7.0, a frequency of 100 s−1, a scan increment of 2 mV and a square wave amplitude of 50 mV. Under such conditions, the variation of paraquat concentrations
from 5.00 × 10−7 to 2.91 × 10−5 mol L−1 showed a linear relation, with detection and quantification limits of 26.53 and 88.23 μg L−1; those values were lower than the maximum limits for drinking water permitted by the Brazilian Environmental Council (100 μg
L−1), indicating that the method could be employed to analyze paraquat in drinking water samples. 相似文献
44.
Bozena Winnik Dana B. Barr Mona Thiruchelvam M. Angela Montesano Eric K. Richfield Brian Buckley 《Analytical and bioanalytical chemistry》2009,395(1):195-201
Animal models, consistent with the hypothesis of direct interaction of paraquat (PQ) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine
(MPTP) with specific areas of the central nervous system have been developed to study Parkinson’s disease (PD) in mice. These
models have necessitated the creation of an analytical method for unambiguous identification and quantitation of PQ and structurally
similar MPTP and 1-methyl-4-phenylpyridinium ion (MPP+) in brain tissue. A method for determination of these compounds was developed using microwave-assisted solvent extraction
(MASE) and liquid chromatography–mass spectrometry. Extraction solvent and microwave conditions such as power and time were
optimized to produce recoveries of 90% for PQ 78% for MPTP and 97% for its metabolite MPP+. The chromatographic separation was performed on a C8, column and detection was carried out using an ion trap as an analyzer
with electrospray ionization. Mass spectrometer parameters such as heated capillary temperature, spray voltage, capillary
voltage and others were also optimized for each analyte. Analysis was done in selective ion-monitoring (SIM) mode using m/z 186 for PQ, m/z 174 for MPTP, and m/z 170 for MPP+. The method detection limit for paraquat in matrix was 100 pg, 40 pg for MPTP, and 20 pg MPP+. 相似文献
45.
《Analytical letters》2012,45(15):1235-1252
Abstract A rapid method was developed for the analysis of paraquat dication (I) and diquat dication (II) as their diene reduction products (ID and IID respectively) in potatoes. Macerated potato tissue was spiked with various levels of the dications, 0.05, 0.5, and 5.0 ppm. The dications were reduced using a sodium borohydride/ethanol reduction procedure with reduction and simultaneous extraction in a single 50 ml glass-stoppered centrifuge tube. The diene reduction products were extracted into hexane and analyzed by gas-liquid chromatography (GLC) and a N/P-thermionic detector. Quantification by external standard method or internal standard method resulted in recoveries of 35, 38, 48 and 39,42, 64% for diquat and paraquat respectively. When a spiked macerate was well-mixed, recoveries were low due to adsorption; precision was within 5 5.4% (standard deviation). The importance of spiking technique was also illustrated. Upon thorough mixing and equilibration, of diquat spiked potatoes, recoveries were reduced dramatically. Adsorption of the dications and diene reduction products to glassware reduced recoveries and accounted for poorer precision; this latter effect was overcome by prior silanization of the glassware. Modification of existing NaBH4 methods resulted in a procedure for I and II analysis requiring only 30 minutes per sample for complete analysis. Use of NaBH4 reduction and analysis of I in potatoes has not been previously reported. 相似文献
46.
G. Franke W. Pietrulla und K. Preußner 《Fresenius' Journal of Analytical Chemistry》1979,298(1):38-42
Zusammenfassung Es wird eine empfindliche und spezifische Differential-puls-polarographische Methode zum direkten quantitativen Nachweis von Paraquat (P) in ammoniakalischer Ammoniumchloridlösung (pH 8), Urin (pH 7) und Serum (pH 6,5–8) beschrieben. Die Peakpotentiale (E
p
) in mV, gemessen gegen eine gesättigte Kalomelelektrode, sind für die ammoniakalische Ammoniumchloridlösung –686 mV, für Urin –679 mV und für Serum –692 mV. Die Analysen von Urin und Serum wurden für Paraquat-vergiftete und auch für gesunde Personen mit Paraquatzusatz durchgeführt. Die Zeit für eine vollständige Analyse beträgt 25 min. Die Nachweisgrenze beträgt in der ammoniakalischen Ammoniumchloridlösung 0,03 g P/ml, im Urin 0,05 g P/ml und im Serum 0,03 g P/ml.
Quantitative determination of paraquat in urine and serum by differential pulse polarography
Summary A sensitive and specific differential pulse polarographic method for the direct quantitative determination of paraquat (P) in ammoniacal ammonium chloride solution (pH 8), urine (pH 7) and serum (pH 6.5–8) is described. The peak potentials (E p ) in mV vs. saturated calomel electrode (SCE) were –686 mV for ammoniacal ammonium chloride solution, –679 mV for urine, and –692 mV for serum. Analyses were performed in urine and serum both from persons poisoned with paraquat and from healthy persons. Urine and serum from the latter to which paraquat had been added served as control. The time needed for one complete analysis was 25 min. Detection limits were 0,03 g P/ml for ammoniacal ammonium chloride solution, 0,05 g P/ml for urine and 0,03 g P/ml for serum.
Die Verfasser danken Fräulein M. Schneider und Herrn H. Bewig für die sorgfältige Durchführung von Messungen. 相似文献
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The voltammetric behavior of paraquat was investigated at hydroxyapatite‐modified carbon paste electrode HAP‐CPE in K2SO4. A method was developed for the detection of the trace of this herbicide, based on their redox reaction. The reduction peaks of paraquat were observed around ?0.70 V and ?1.00 V (vs. SCE) in square‐wave voltammetry. Experimental conditions were optimized by varying the accumulation time, apatite loading and measuring solution pH. Calibration plots were linear under the optimized parameters over the herbicide's concentration range 8–200×10?7 mol L?1, with a detection and quantification limits about 1.5×10?8 mol L?1 and 6.4 10?8 mol L?1, respectively. 相似文献
49.
S. Sideman N. Lotan A. Tabak D. Manor L. Mor U. Taitelman J. Brook A. Tzipiniuk 《Applied biochemistry and biotechnology》1984,10(1-3):167-182
Composite beads of approximately 1mm diameter, made of cross-linked agarose and containing Fuller’s Earth or zirconium oxide
powders, were prepared and used in extracorporeal systems for blood detoxification. The former was used for the removal of
Paraquat, while the latter was used to remove inorganic phosphate from hyper-phosphatamic animals with or without acute renal
failure. The high surface area of the powder, combined with the low resistance to diffusion in the cross-linked agarose matrix,
are highly advantageous. The crosslinking provides high mechanical strength, heat stability, prolonged shelf life, good blood
flow characteristics, and prevents the release of fine particles into the blood.
Crosslinked agarose beads of 1 mm diameter, containing chemically-bound heparin were also prepared, and used as a model for
direct contact removal of LDL-cholesterol from the blood of familial hypercholesterolemic patients by hemoperfusion. The high
capacity of these beads (over 5 mg LDL/mL beads) indicates that this clinical modality can replace the highly expensive plasmapheresis
procedure presently used. 相似文献
50.
《Tetrahedron》2018,74(39):5725-5732
A new synthetic route to the molecular clip with diphenylglycoluril and dibenzo-18-crown-6 using protection-deprotection protocol is proposed. Yield of desired compound has increased from 10-15% to 41%. Starting from 4,5-dibromobenzene-1,2-diol 4,5-dibromodibenzo-18-crown-6 and then tetrabromo-substituted molecular clip were obtained. The target molecular clip was obtained by bromine cleavage by hydrogenolysis. Stability constants were determined by spectrophotometric titration with alkali metal cations and paraquat. Quantum-chemical calculations confirm the assumption of additional stabilization of complex with K+ by π–π stacking between the terminal aromatic fragments with formation of a “pseudocryptand” type structure. The structures of complexes of the molecular clips with paraquat were determined by X-ray crystallography. 相似文献