Degradation of the insecticides fipronil and cypermethrin in green onions (Allium fistulosum) and mustard greens (Brassica juncea)

Pesticide dissipation on foods like vegetables, fruits, and cereals is one of the most concerning aspects in pesticide toxicology as it involves risks to human health and food safety. In light if this, a laboratory-scale study was conducted for two separate systems, green onions (Allium fistulosum) and mustard greens (Brassica juncea),in order to identify the dissipation of fipronil and cypermethrin, two commonly used insecticides, under a tropical climate. After the pesticide application, vegetable samples from these microcosms were collected each day for 7 days to measure fipronil and cypermethrin (n=3) residues. The analytical method was validated and showed repeatability and trueness. The decay equations fit well to first-order kinetics with a correlation coefficient of R2>0.93 and p<0.0005. The calculated half-life values of fipronil were 2.9 d for green onions and 3.2 d for mustard greens while those of cypermethrin were, respectively, 4.5 d and 3.2 d. To meet the maximum residue levels (MRL) of fipronil (0.02 mg/kg) and cypermethrin (0.7 mg/kg) on vegetables, the estimated pre-harvest intervals should be updated to 23 d and 7.5 d, respectively.

Download Full-text

Metribuzin Persistence in Soil

Weed Science ◽

10.1017/s0043174500032914 ◽

1977 ◽

Vol 25 (1) ◽

pp. 55-59 ◽

Cited By ~ 39

Author(s):

K.E. Savage

Keyword(s):

Mississippi River ◽

Soil Type ◽

Soil Types ◽

Microbiological Activity ◽

First Order ◽

Residue Detection ◽

Chromatographic Techniques ◽

First Order Kinetics ◽

Alluvial Floodplain ◽

Life Values

The persistence of metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazine-5(4H)-one] in several soils from the lower alluvial floodplain of the Mississippi River was studied in the greenhouse and laboratory using bioassay and gas chromatographic methods of residue detection. Bioassay results indicated that metribuzin phytotoxicity was lost in several soil types within a few weeks of application. Longevity of phytotoxicity depended upon soil type. However soil type had little effect on the rate of metribuzin degradation measured chemically. Gas chromatographic techniques indicated that metribuzin degradation followed first-order kinetics with half-life values ranging from 17 to 28 days in six soils under greenhouse conditions. Incubation studies indicated that metribuzin was degraded more rapidly in nonautoclaved field soil and in soil enriched with glucose than in soil that had been air dry for 1 yr or had been autoclaved. Degradation was more rapid at 30 C than at 20 C. Microbiological activity apparently is important in the degradation of metribuzin in soil.

Download Full-text

Dissipation and Residues of Thiram in Potato and Soil

Journal of Chemistry ◽

10.1155/2015/623847 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Shaowen Liu ◽

Aijuan Bai ◽

Li Zhou ◽

Chuanshan Yu ◽

Yanjie Li ◽

...

Keyword(s):

High Performance ◽

Residue Field ◽

High Concentration ◽

Recommended Dosage ◽

Potato Leave ◽

First Order ◽

First Order Kinetics ◽

Wettable Powder ◽

Residue Levels ◽

Derivation Method

The residue levels of thiram during potato cultivation in open field were evaluated. Thiram residues were determined by methylation derivation method with high performance liquid chromatography (HPLC). Wettable powder (WP) formulation containing 25% thiram was applied at 2320 g active gradient hm−2(a.i. hm−2) dosage for the dissipation study. The decline rate in potato leave and soil followed first-order kinetics equation, and the half-life ranged from 2.8 to 5.4 days and 2.6 to 9.9 days, respectively. In terminal residue, the thiram was sprayed at 580 g a.i. hm−2(low concentration, recommended dosage) and 1160 g a.i. hm−2(high concentration, double of recommended dosage). The residues of thiram in potato and soil samples collected in the field at preharvest interval of 21 days and 30 days were all below 0.02 mg kg−1. The results show that thiram possesses low dietary risk in potato at harvest according to supervised residue field trial. It may be safe when used at recommended rate of application.

Download Full-text

Dissipation Behavior of a Mancozeb Residue (Dithiocarbamate Fungicide) in Tomato Under South Moroccan Climatic Condition

IRA-International Journal of Applied Sciences (ISSN 2455-4499) ◽

10.21013/jas.v7.n2.p2 ◽

2017 ◽

Vol 7 (2) ◽

pp. 62

Author(s):

El Habib Ait Addi

Keyword(s):

Open Field ◽

Climatic Condition ◽

Degradation Rate ◽

Recommended Dose ◽

Order Kinetic ◽

Acid Digestion ◽

Pesticide Application ◽

Simple Method ◽

First Order ◽

Residue Levels

<div><p><em>Dissipation behavior of mancozeb, a widely used dithiocarbamte fungicide, applied under field condition on tomato at recommended dose was undertaken under greenhouses and open field during October and March in Souss-Massa area (south of Morocco) climatic condition. Residue levels of mancozeb were determined by using a simple method consisting in a hot acid digestion of the whole sample to evolve carbon disulfide (CS<sub>2</sub>), which is further quantified by spectrophotometry. Degradation rate in both open field and greenhouse followed first order kinetic. Half lives were 1.77 and 1.3 days in open field and in greenhouse were 2.0 and 1.8 days for October and March period respectively. Based on the observation reported, a pre harvested interval of at least three days after pesticide application at recommended dose may be suggested.</em></p></div>

Download Full-text

Soil Residual Properties of DPX-A7881 Under Laboratory Conditions

Weed Science ◽

10.1017/s0043174500072143 ◽

1989 ◽

Vol 37 (3) ◽

pp. 412-418 ◽

Cited By ~ 18

Author(s):

Hugh J. Beckie ◽

Robert B. McKercher

Keyword(s):

Lateral Roots ◽

Alkaline Soils ◽

First Order ◽

Residual Properties ◽

First Order Kinetics ◽

Significant Temperature ◽

Residue Levels ◽

Chamber Studies ◽

Growth Chamber Studies ◽

Primary Lateral

Growth chamber studies were conducted to examine the soil residual properties of DPX-A7881, a new sulfonylurea herbicide. The phytotoxic residue levels in the soil were determined by a lentil radicle bioassay. The duration of activity was prolonged in soil adjusted to pH 7.6 and 8.1 relative to more acidic levels. The rate of breakdown in the soil was enhanced with increased temperature and soil moisture content; a significant temperature by moisture interaction was noted over the duration of the incubation period. The dissipation of DPX-A7881 in soil obeyed first-order kinetics in both studies. An accelerated rate of breakdown in unsterilized versus sterilized soil (pH 7.6) indicated that microbial degradation was an important factor affecting the persistence in alkaline soils. Herbicide residues in the soil caused a reduction in taproot length and number of primary lateral roots of canola seedlings 15 days after planting but there were no other morphological effects observed on the root. The secondary laterals, however, had generally recovered by this time.

Download Full-text

PREDICTION OF THE PERSISTENCE OF THE TRIAZINE HERBICIDES ATRAZINE, CYANAZINE, AND METRIBUZIN IN REGINA HEAVY CLAY

Canadian Journal of Soil Science ◽

10.4141/cjss89-059 ◽

1989 ◽

Vol 69 (3) ◽

pp. 587-595 ◽

Cited By ~ 32

Author(s):

A. E. SMITH ◽

A. WALKER

Keyword(s):

Reasonable Agreement ◽

Clay Soil ◽

Laboratory Data ◽

Growing Season ◽

First Order ◽

First Order Kinetics ◽

Heavy Clay ◽

Dissipation Pattern ◽

Residue Levels ◽

Good Agreement

The persistence of the herbicides cyanazine, metribuzin, and atrazine was studied at different controlled temperature and moisture contents in Regina Heavy Clay soil. Degradation of the herbicides approximated first-order kinetics at temperatures in the range 5–30 °C and at moistures of above 20%. The breakdown of cyanazine was faster than metribuzin, which, in turn, was more rapid than atrazine. The breakdown of the three herbicides under field conditions, following June applications of 1.0 kg ha−1, was measured. Over 90% of the applied cyanazine had dissipated within 56 d, while the metribuzin and atrazine were more persistent, with approximately 30% of the initial treatment remaining at the end of the growing season. In all cases, there was no leaching of the chemicals below 10 cm. The laboratory data were used in conjunction with meteorological records in a computer program to simulate the dissipation pattern for the herbicides. There was good agreement between the observed and predicted residue levels for cyanazine, and a reasonable agreement for atrazine. For metribuzin, the model underestimated the rate of loss. Key words: Herbicides, atrazine, cyanazine, metribuzin, predicted field persistence

Download Full-text

Photo-catalytic degradation of gaseous pollutants in paper mills of southern China

TAPPI Journal ◽

10.32964/tj17.03.167 ◽

2018 ◽

Vol 17 (03) ◽

pp. 167-178 ◽

Cited By ~ 2

Author(s):

Xin Tong ◽

Jiao Li ◽

Jun Ma ◽

Xiaoquan Chen ◽

Wenhao Shen

Keyword(s):

Degradation Rate ◽

Southern China ◽

Catalytic Degradation ◽

Pulp And Paper ◽

Gaseous Pollutants ◽

Pulp And Paper Mills ◽

Paper Mills ◽

Initial Concentration ◽

First Order ◽

First Order Kinetics

Studies were undertaken to evaluate gaseous pollutants in workplace air within pulp and paper mills and to consider the effectiveness of photo-catalytic treatment of this air. Ambient air at 30 sampling sites in five pulp and paper mills of southern China were sampled and analyzed. The results revealed that formaldehyde and various benzene-based molecules were the main gaseous pollutants at these five mills. A photo-catalytic reactor system with titanium dioxide (TiO2) was developed and evaluated for degradation of formaldehyde, benzene and their mixtures. The experimental results demonstrated that both formaldehyde and benzene in their pure forms could be completely photo-catalytic degraded, though the degradation of benzene was much more difficult than that for formaldehyde. Study of the photo-catalytic degradation kinetics revealed that the degradation rate of formaldehyde increased with initial concentration fitting a first-order kinetics reaction. In contrast, the degradation rate of benzene had no relationship with initial concentration and degradation did not conform to first-order kinetics. The photo-catalytic degradation of formaldehyde-benzene mixtures indicated that formaldehyde behaved differently than when treated in its pure form. The degradation time was two times longer and the kinetics did not reflect a first-order reaction. The degradation of benzene was similar in both pure form and when mixed with formaldehyde.

Download Full-text

Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

10.31221/osf.io/m9g7p ◽

2019 ◽

Author(s):

Chem Int

Keyword(s):

Methyl Orange ◽

Solution Ph ◽

Vanadium Concentration ◽

Limiting Behavior ◽

First Order ◽

First Order Kinetics ◽

Ph Range ◽

Kinetic Pattern ◽

Triton X ◽

Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

Download Full-text

Biodegradation rates of aromatic contaminants in biofilm reactors

Water Science & Technology ◽

10.2166/wst.1995.0027 ◽

1995 ◽

Vol 31 (1) ◽

pp. 117-128 ◽

Cited By ~ 8

Author(s):

Jean-Pierre Arcangeli ◽

Erik Arvin

Keyword(s):

Aromatic Hydrocarbons ◽

Competitive Inhibition ◽

Removal Rate ◽

First Order ◽

Biofilm Reactors ◽

First Order Kinetics ◽

Reducing Conditions ◽

Low Concentrations ◽

Degradation Rates ◽

Order Surface

This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic compounds was typically controlled by first order kinetics. The first-order surface removal rate constants were surprisingly similar, ranging from 2 to 4 m/d. It appears that NSO-compounds inhibit the degradation of aromatic hydrocarbons, even at very low concentrations of NSO-compounds. Under nitrate-reducing conditions, toluene was easily biodegraded. The xylenes and ethylbenzene were degraded cometabolically if toluene was used as a primary carbon source; their removal was influenced by competitive inhibition with toluene. These interaction phenomena are discussed in this paper and a kinetic model taking into account cometabolism and competitive inhibition is proposed.

Download Full-text

In-vitro Kinetic Hydrolysis Study of Metronidazole Derivatives with Carvacrol and Eugenol Using Validated RP-HPLC Method

Current Pharmaceutical Analysis ◽

10.2174/1573412916999200529123151 ◽

2020 ◽

Vol 16 ◽

Author(s):

M. Alarjah

Keyword(s):

Half Life ◽

Hplc Method ◽

Hydrolysis Rate ◽

First Order ◽

First Order Kinetics ◽

Rp Hplc ◽

Pharmacokinetic Properties ◽

Pseudo First Order ◽

Kinetic Hydrolysis

Background: Prodrugs principle is widely used to improve the pharmacological and pharmacokinetic properties of some active drugs. Much effort was made to develop metronidazole prodrugs to enhance antibacterial activity and or to improve pharmacokinetic properties of the molecule or to lower the adverse effects of metronidazole. Objective: In this work, the pharmacokinetic properties of some of monoterpenes and eugenol pro metronidazole molecules that were developed earlier were evaluated in-vitro. The kinetic hydrolysis rate constants and half-life time estimation of the new metronidazole derivatives were calculated using the validated RP-HPLC method. Method: Chromatographic analysis was done using Zorbbax Eclipse eXtra Dense Bonding (XDB)-C18 column of dimensions (250 mm, 4.6 mm, 5 μm), at ambient column temperature. The mobile phase was a mixture of sodium dihydrogen phosphate buffer of pH 4.5 and methanol in gradient elution, at 1ml/min flow rate. The method was fully validated according to the International Council for Harmonization (ICH) guidelines. The hydrolysis process carried out in an acidic buffer pH 1.2 and in an alkaline buffer pH 7.4 in a thermostatic bath at 37ºC. Results: The results followed pseudo-first-order kinetics. All metronidazole prodrugs were stable in the acidic pH, while they were hydrolysed in the alkaline buffer within a few hours (6-8 hr). The rate constant and half-life values were calculated, and their values were found to be 0.082- 0.117 hr-1 and 5.9- 8.5 hr., respectively. Conclusion: The developed method was accurate, sensitive, and selective for the prodrugs. For most of the prodrugs, the hydrolysis followed pseudo-first-order kinetics; the method might be utilised to conduct an in-vivo study for the metronidazole derivatives with monoterpenes and eugenol.

Download Full-text

Decomposition of 4,4'-(Diazoamino)-bis(5-methoxy-2-methylbenezenesulfonic Acid) in Solutions ofFD&C Red No. 40

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/67.4.844 ◽

1984 ◽

Vol 67 (4) ◽

pp. 844-845

Author(s):

Naomi Richfield-Fratz

Keyword(s):

Liquid Chromatography ◽

Aqueous Solutions ◽

Borate Buffer ◽

Sodium Borate ◽

First Order ◽

First Order Kinetics ◽

Color Additive ◽

Sodium Borate Buffer

Abstract 4,4'-(Diazoamino)-bis(5-methoxy-2-methylbenzenesuIfonic acid), when present as a reaction by-product in FD&C Red No. 40, is shown to decompose rapidly in aqueous solutions of the color additive. The decomposition is halted by the addition of sodium borate buffer. Quantitationly liquid chromatography shows that decomposition is nonlinear with time and follows approximate first order kinetics.

Download Full-text