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1.
J Environ Sci Health B ; 49(2): 134-41, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24328546

RESUMEN

This paper reports the in vitro and in vivo bioefficacy of a combination fungicide trifloxystrobin (25%) + tebuconazole (50%) against early blight disease of tomato (Lycopersicon esculentum Mill.) caused by Alternaria solani and their corresponding pre-harvest intervals (PHI) with reference to the maximum residue limits (European Union). Bioefficacy of the test fungicide combination revealed that in vitro conditions manifested the best control (75.1%) at 350 mg kg(-1) against 76.2% control under field conditions. A sample preparation method based on ethyl acetate extraction and estimation by LC-MS multiple reaction monitoring (MRM) was validated in tomato fruits at 0.01 mg/kg and dissipation studies were conducted in field at single and double doses. The residues of both the compounds on all the sampling days were below the European Union maximum residue limits (EU-MRLs) and the maximum permissible intakes (MPIs) were calculated on the basis of prescribed acceptable daily intake (ADI). The combined bioefficacy and residue dynamics information will support label-claim of this fungicide combination for the management of early blight in tomato.


Asunto(s)
Acetatos/efectos adversos , Alternaria/efectos de los fármacos , Fungicidas Industriales/efectos adversos , Iminas/efectos adversos , Residuos de Plaguicidas/efectos adversos , Enfermedades de las Plantas/prevención & control , Solanum lycopersicum , Triazoles/efectos adversos , Cromatografía Liquida , Relación Dosis-Respuesta a Droga , Unión Europea , Solanum lycopersicum/microbiología , Espectrometría de Masas , Metacrilatos/efectos adversos , Enfermedades de las Plantas/microbiología , Estrobilurinas
2.
Environ Monit Assess ; 186(4): 2369-74, 2014 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-24287718

RESUMEN

A field dissipation study was conducted to evaluate the pre-harvest interval (PHI) and processing factor (PF) for kresoxim methyl (Ergon 44.3 SC) residues in grapes and during raisin making process at recommended dose (RD) and double the recommended dose (DRD). Kresoxim methyl residues dissipated following 1st-order kinetics with a half-life of 10 and 18 days at RD and DRD, respectively. The PHIs with respect to the European Union maximum residue limit (EU-MRL) of 1 mg kg(-1) for grapes were 13 and 30 days at RD and DRD, respectively. The degradation data during grape to raisin making process were best fitted to nonlinear 1st + 1st-order kinetics with a half-life ranging between 4 and 8 days for both shade drying and with raisin dryer at different doses. The PFs were 1.19 and 1.24 with shade drying and 1.09 and 1.10 with raisin dryer, respectively, which indicates concentration of the residues during raisin making process. The dietary exposure of kresoxim methyl on each sampling day was less than the respective maximum permissible intake both at RD and DRD. The residues of kresoxim methyl in market samples of grapes and raisins were well below the EU-MRL and were also devoid of any risk of acute toxicity related to dietary exposure.


Asunto(s)
Monitoreo del Ambiente , Fungicidas Industriales/análisis , Residuos de Plaguicidas/análisis , Fenilacetatos/análisis , Vitis/química , Unión Europea , Contaminación de Alimentos/análisis , Contaminación de Alimentos/estadística & datos numéricos , Fungicidas Industriales/química , Semivida , Cinética , Metacrilatos/análisis , Metacrilatos/química , Residuos de Plaguicidas/química , Fenilacetatos/química , Medición de Riesgo , Estrobilurinas
3.
J Environ Sci Health B ; 47(7): 700-9, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22560033

RESUMEN

This paper reports the bioefficacy of selected insecticides against thrips and their pre-harvest intervals (PHI) in onion pertaining to their recommended application rates and maximum residue limits. Profenophos, methomyl and imidacloprid showed comparatively higher bioefficacy against thrips. GC-MS and LC-MS/MS-based residue analysis methods in onion bulbs and composite matrix of bulbs+leaves were thoroughly validated. The residue data for bulb+leaves was assessed with reference to the EU-MRLs applicable for spring onion. Dimethoate was the most stable chemical with PHI of 52.5 days, followed by monocrotophos (24 days) and carbofuran (20.5 days). The PHIs of profenophos, chlorpyrifos, methomyl and cypermethrin were similar and within the range of 10-13 days. Imidacloprid and λ-cyhalothrin had similar PHI of 4.5 days. Spinosad was the fastest-degrading chemical with PHI of 2 days. The combined bioefficacy and residue dynamics information will support label-claim of these insecticides for the management of thrips in onion, help in scheduling their applications in pest management program as per relative PHIs and minimize the residue accumulations at harvest. The dietary exposure was less than the maximum permissible intake for most of the insecticides on all sampling days except for dimethoate and monocrotophos.


Asunto(s)
Insecticidas/química , Insecticidas/farmacología , Cebollas/parasitología , Enfermedades de las Plantas/parasitología , Thysanoptera/efectos de los fármacos , Animales , Control de Insectos , Cinética
4.
J AOAC Int ; 94(3): 968-77, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-21797026

RESUMEN

A selective and rapid multiresidue analysis method is presented for simultaneous estimation of 12 plant growth regulators (PGRs), namely, auxins (indol-3-acetic acid, indol-3-butyric acid, and naphthyl acetic acid), cytokinins (kinetin, zeatin, and 6-benzyladenine), gibberellic acid (GA3), abscisic acid, and synthetic compounds, namely, forchlorfenuron, paclobutrazole, isoprothiolane, and 2,4-dichlorophenoxy acetic acid (2,4-D) in bud sprouts and grape berries at the development stages of 2-3 and 6-8 mm diameters, which are the critical phases when exogenous application of PGRs may be necessary to achieve desired grape quality and yield. The sample preparation method involved extraction of plant material with acidified methanol (50%) by homogenization for 2 min at 15000 rpm. The pH of the extract was enhanced up to 6 by adding ammonium acetate, followed by homogenization and centrifugation. The supernatant extract was cleaned by SPE on an Oasis HLB cartridge (200 mg, 6 cc). The final extract was measured directly by LC/MS/MS with electrospray ionization in positive mode, except for 2,4-D, GA3, and abscisic acid extracts, which required analysis in negative mode. Quantification by multiple reaction monitoring (MRM) was supported with full-scan mass spectrometric confirmation using "information-dependent acquisition" triggered with MRM to "enhanced product ionization" mode of the hybrid quadrupole-ion trap mass analyzer. The LOQ of the test analytes varied between 1 and 10 ng/g with associated recoveries of 80-120% and precision RSD <25% (n = 8). Significant matrix-induced signal suppression was recorded when the responses for pre- and postextraction spikes of analytes were compared; this could be resolved by using matrix-matched calibration standards. The method could successfully be applied in analyzing incurred residue samples and would, therefore, be useful in precisely deciding the necessity and dose of exogenous applications of PGRs on the basis of measured endogenous levels.


Asunto(s)
Cromatografía Liquida/métodos , Frutas/química , Reguladores del Crecimiento de las Plantas/química , Espectrometría de Masas en Tándem/métodos , Vitis/química , Estructura Molecular , Reguladores del Crecimiento de las Plantas/clasificación
5.
J AOAC Int ; 93(6): 1957-64, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-21313826

RESUMEN

An analytical method is reported for residue analysis of the fungicide meptyldinocap in different fruit matrixes that involves extraction with ethyl acetate, hydrolysis of the residues with ethanolamine, and determination by LC/MS/MS. The method involves extraction of 10 g sample with 10 mL ethyl acetate; evaporation of the ethyl acetate phase to dryness, and subsequent hydrolysis of the residues to 4,6-dinitro-2-(1-methylheptyl) phenol on reaction with 1% ethanolamine. The pH of this hydrolyzed product was neutralized with formic acid and analyzed by LC/MS/MS. The hydrolysis reaction followed pseudo-first-order kinetics, and the reaction product was spectroscopically confirmed as 2-(1-methylheptyl)-4,6-dinitrophenol. The method offered > 80% recoveries at an LOQ of 10 ng/g for grape and mango, 25 ng/g for pomegranate with intralaboratory Horwitz ratio < 0.5, and measurement uncertainties < 10% at LOQ levels. Considering first-order rate kinetics, activation energy, enthalpy of activation, and entropy of activation varied as solvent > mango > grape > pomegranate. Free energy of activation at 298 K was higher than at 280 K and was similar for solvent and three matrixes at both temperatures.


Asunto(s)
Dinitrobencenos/análisis , Frutas/química , Fungicidas Industriales/análisis , Residuos de Plaguicidas/análisis , Acetatos , Cromatografía Líquida de Alta Presión , Costos y Análisis de Costo , Formiatos , Hidrólisis , Indicadores y Reactivos , Cinética , Espectroscopía de Resonancia Magnética , Estándares de Referencia , Reproducibilidad de los Resultados , Tamaño de la Muestra , Soluciones , Solventes , Espectrofotometría Infrarroja , Espectrofotometría Ultravioleta , Espectrometría de Masas en Tándem , Termodinámica
6.
Food Chem ; 272: 292-305, 2019 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-30309547

RESUMEN

This paper reports a unified sample preparation approach for high-throughput multi-residue analysis of veterinary drugs and pesticides in a single sub-sample of bovine milk. The sample (5 g) was deproteinized with acetonitrile before an aliquot (I) was withdrawn, and the remainder was phase-separated using MgSO4 and NaCl. The acetonitrile layer (II) was recovered and the extracts combined, cleaned, and solvent-exchanged before the concentrations of veterinary drugs and pesticides were measured by ultra-fast liquid chromatography tandem mass spectrometry (UFLC-MS/MS). As a unique approach, extract II was analyzed simultaneously using gas chromatography tandem mass spectrometry (GC-MS/MS). Method performance for 78 drugs and 238 pesticides complied with CD 2002/657/EC and SANTE/11813/2017 guidelines, respectively, with significant savings in time and cost. Thus, it would be ideal for regulatory analysis of analytes ranging from non-polar organochlorine pesticides to polar drugs, including penicillins, quinolones, and tetracyclines.


Asunto(s)
Análisis de los Alimentos/métodos , Contaminación de Alimentos/análisis , Cromatografía de Gases y Espectrometría de Masas , Leche/química , Residuos de Plaguicidas/análisis , Espectrometría de Masas en Tándem , Drogas Veterinarias/análisis , Animales , Bovinos , Cromatografía Liquida , Solventes/química
7.
J Agric Food Chem ; 63(18): 4449-56, 2015 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-25639652

RESUMEN

A buffered ethyl acetate extraction method is proposed for the simultaneous analysis of 296 agrochemicals in a wide range of fruit and vegetable matrices by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The optimized quantity of acetate buffer (1% acetic acid + 0.5 g of sodium acetate per 10 g of sample) adjusted the pH of each test matrix to 5-6, which in turn significantly improved recoveries of acidic and basic compounds. The role of diethylene glycol (used in the evaporation step) on signal suppression of certain compounds was evaluated, and its quantity was optimized to minimize such an effect. The method was validated in grape, mango, drumstick, bitter gourd, capsicum, curry leaf, and okra as per the DG-SANCO/12571/2013 guidelines. Recoveries in the fortification range of 1-40 µg/kg were within 70-120% with associated relative standard deviations below 20% for most of the compounds. The method has potential for regulatory and commercial applications with a generic approach.


Asunto(s)
Agroquímicos/química , Agroquímicos/aislamiento & purificación , Fraccionamiento Químico/métodos , Cromatografía Líquida de Alta Presión/métodos , Frutas/química , Espectrometría de Masas en Tándem/métodos , Verduras/química , Contaminación de Alimentos/análisis
8.
ACS Med Chem Lett ; 6(11): 1111-6, 2015 Nov 12.
Artículo en Inglés | MEDLINE | ID: mdl-26617963

RESUMEN

Known morpholine class antifungals (fenpropimorph, fenpropidin, and amorolfine) were synthetically modified through silicon incorporation to have 15 sila-analogues. Twelve sila-analogues exhibited potent antifungal activity against different human fungal pathogens such as Candida albicans, Candida glabrata, Candida tropicalis, Cryptococcus neoformans, and Aspergillus niger. Sila-analogue 24 (fenpropimorph analogue) was the best in our hands, which showed superior fungicidal potential than fenpropidin, fenpropimorph, and amorolfine. The mode of action of sila-analogues was similar to morpholines, i.e., inhibition of sterol reductase and sterol isomerase enzymes of ergosterol synthesis pathway.

9.
J Agric Food Chem ; 61(36): 8491-8, 2013 Sep 11.
Artículo en Inglés | MEDLINE | ID: mdl-23944960

RESUMEN

A single-step methanol extraction based method was developed and validated for simultaneous estimation of the residues of streptomycin and tetracycline group compounds in pomegranate fruits by LC-MS/MS. The limits of quantification for all target compounds were ≤0.005 mg kg(-1) with recoveries (%) at fortification levels of 0.005, 0.01, and 0.05 mg kg(-1) being within 90-116% (RSD ≤ 9%) and interday precision RSD ≤ 12% at 0.01 mg kg(-1). A field experiment on the dissipation of streptomycin and tetracycline (including 4-epimers) residues in pomegranate fruits with regards to field applications of the commercial formulation Streptocycline SP (streptomycin sulfate 90% + tetracycline hydrochloride 10%) at 200 and 400 g a.i. ha(-1) indicated preharvest intervals of 45 and 55 days for streptomycin and 12 and 15 days for tetracycline, respectively. The study will be useful in promoting effective residue monitoring and ensuring safe use of these antibiotics in managing bacterial diseases of pomegranate.


Asunto(s)
Antibacterianos/análisis , Inocuidad de los Alimentos/métodos , Frutas/química , Lythraceae/química , Estreptomicina/análisis , Tetraciclina/análisis , Cromatografía Liquida/métodos , Residuos de Medicamentos/análisis , Contaminación de Alimentos/análisis , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/prevención & control , Espectrometría de Masas en Tándem/métodos
10.
J Agric Food Chem ; 59(14): 7866-73, 2011 Jul 27.
Artículo en Inglés | MEDLINE | ID: mdl-21671616

RESUMEN

The dissipation behavior and degradation kinetics of azoxystrobin, carbendazim, and difenoconazole in pomegranate are reported. Twenty fruits/hectare (5 kg) were collected at random, ensuring sample-to-sample relative standard deviation (RSD) within 20-25%. Each fruit was cut into eight equal portions, and two diagonal pieces per fruit were drawn and combined to constitute the laboratory sample, resulting in RSDs <6% (n = 6). Crushed sample (15 g) was extracted with 10 mL of ethyl acetate (+ 10 g Na(2)SO(4)), cleaned by dispersive solid phase extraction on primary secondary amine (25 mg) and C(18) (25 mg), and measured by liquid chromatography tandem mass spectrometry. The limit of quantification was ≤0.0025 µg g(-1) for all the three fungicides, with calibration linearity in the concentration range of 0.001-0.025 µg mL(-1) (r(2) ≥ 0.999). The recoveries of each chemical were 75-110% at 0.0025, 0.005, and 0.010 µg g(-1) with intralaboratory Horwitz ratio <0.32 at 0.0025 µg g(-1). Variable matrix effects were recorded in different fruit parts viz rind, albedo, membrane, and arils, which could be correlated to their biochemical constituents as evidenced from accurate mass measurements on a Q-ToF LC-MS. The residues of carbendazim and difenoconazole were confined within the outer rind of pomegranate; however, azoxystrobin penetrated into the inner fruit parts. The dissipation of azoxystrobin, carbendazim, and difenoconazole followed first + first order kinetics at both standard and double doses, with preharvest intervals being 9, 60, and 26 days at standard dose. At double dose, the preharvest intervals extended to 20.5, 100, and 60 days, respectively.


Asunto(s)
Bencimidazoles/química , Carbamatos/química , Dioxolanos/análisis , Frutas/química , Fungicidas Industriales/química , Lythraceae/química , Metacrilatos/química , Residuos de Plaguicidas/química , Pirimidinas/química , Triazoles/análisis , Contaminación de Alimentos/análisis , Cinética , Estrobilurinas
11.
J Agric Food Chem ; 57(10): 4068-78, 2009 May 27.
Artículo en Inglés | MEDLINE | ID: mdl-19378943

RESUMEN

A liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method was optimized and validated for the multiresidue analysis of 87 pesticides in mango at the ≤ 10 ng g(-1) level. The method involves extraction of 10 g of homogenized mango samples (+10 mL of water + 1 g of sodium acetate + 10 g of sodium sulfate) with 10 mL of ethyl acetate; cleanup by dispersive solid-phase extraction with a combination of primary secondary amine (PSA, 50 mg), graphitized carbon black (GCB, 25 mg), and anhydrous sodium sulfate (150 mg); and final estimation by LC-MS/MS with multiple reaction monitoring. Direct analysis (no clean up) resulted in significant suppression in ionization of the majority of the test compounds over the electrospray ionization probe. However, clean up with the above combination of PSA + GCB reduced the matrix-induced signal suppressions significantly, and the signals in the cleaned extracts were nearly equivalent to the corresponding solvent standards. Substitution of PSA with florisil also gave equivalent clean up effects. The method was quite rugged as evident from a low Horwitz ratio (mostly <0.5) and low measurement uncertainties at 10 ng g(-1). The limit of quantification was <10 ng g(-1) for all of the pesticides with recoveries within 70-120% for most pesticides even at 2.5 ng g(-1). The method offers a significantly effective, sensitive, cheaper, and safer alternative to the existing methods of multiresidue analysis.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Frutas/química , Mangifera/química , Residuos de Plaguicidas/análisis , Espectrometría de Masas en Tándem/métodos , Cromatografía Líquida de Alta Presión/economía , Costos y Análisis de Costo , Contaminación de Alimentos/análisis , Espectrometría de Masas en Tándem/economía , Incertidumbre
12.
J Chromatogr A ; 1216(12): 2307-19, 2009 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-19215926

RESUMEN

A multiresidue method is described for simultaneous estimation of 83 pesticides and 12 dioxin-like polychlorinated biphenyls (PCBs) in red and white wines. The samples (20mL wine, acidified with 20 mL 1% HCl) were extracted with 10 mL ethyl acetate (+20 g sodium sulphate) and cleaned by dispersive solid-phase extraction (DSPE) with anhydrous calcium chloride and Florisil successively. The final extract (5 mL) was solvent exchanged to 1mL of cyclohexane:ethyl acetate (9:1), further cleaned by DSPE with 25mg primary secondary amine sorbent and analyzed by gas chromatography-time-of-flight mass spectrometry (GC-TOF-MS) within 31 min run time. The limits of quantification of most analytes were 80% for most analytes except cyprodinil, buprofezin and iprodione. The expanded uncertainties at 10 ng/mL were <20% for most analytes. Intra-laboratory precision in terms of Horwitz ratio of all the analytes was below 0.5, suggesting ruggedness of the method. Effectively, the method detection limit for most analytes was as low as up to 1 ng/mL in both red and white wine, except for cyfluthrin and cypermethrin.


Asunto(s)
Cromatografía de Gases y Espectrometría de Masas/métodos , Plaguicidas/análisis , Bifenilos Policlorados/análisis , Vino/análisis , Acetatos/química , Acetonitrilos/química , Cloruro de Calcio/química , Interpretación Estadística de Datos , Etanol/química , Cromatografía de Gases y Espectrometría de Masas/economía , Silicatos de Magnesio/química , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Extracción en Fase Sólida
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