scholarly journals A Fast, Inexpensive, and Safe Method for Residue Analysis of Meptyldinocap in Different Fruits by Liquid Chromatography/Tandem Mass Spectrometry

2010 ◽  
Vol 93 (6) ◽  
pp. 1957-1964 ◽  
Author(s):  
Kaushik Banerjee ◽  
Soma Dasgupta ◽  
Manjusha R Jadhav ◽  
Dattatraya G Naik ◽  
Axel Patrick Ligon ◽  
...  
Keyword(s):  
Ethyl Acetate ◽  
Residue Analysis ◽  
First Order ◽  
First Order Kinetics ◽  
Free Energy Of Activation ◽  
Subsequent Hydrolysis ◽  
Liquid Chromatography Tandem Mass ◽  
Rate Kinetics ◽  
Entropy Of Activation ◽  
Hydrolysis Of

Abstract 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.

The Influence of Sodium Benzoate on the Alkaline Hydrolysis of Fuchsin: Inhibition Study

2021 ◽  
Vol 46 (1) ◽  
Author(s):  
D. F Latona ◽  
A.E Akinola
Keyword(s):  
Alkaline Hydrolysis ◽  
Sodium Benzoate ◽  
Activation Parameters ◽  
First Order ◽  
First Order Kinetics ◽  
Free Energy Of Activation ◽  
Hydrolytic Reaction ◽  
Presence And Absence ◽  
Gibb’S Free Energy ◽  
Hydrolysis Of

Kinetics of alkaline hydrolysis of Fuchsin in the absence and presence of sodium benzoate was investigated at 546.5 nm by pseudo first order kinetics. The reaction was found to be first order each in [Fuchsin] and [NaOH] in the presence and absence of sodium benzoate. Double reciprocal plot indicates the presence of an intermediate complex in the course of the reaction. Activation parameters were obtained from Erying’s equation as ΔH# 24.70 kJmol-1, ΔS# -0.193 kJK-1mol-1 and ΔG# 82.21 kJ mol-1 in the absence of sodium benzoate and ΔH# 27.59 kJmol-1, ΔS# -0.185 kJ K-1mol-1 and ΔG# 82.72 kJ mol-1in the presence of sodium benzoate. Sodium benzoate plays an inhibitory role in the hydrolysis reaction. The values of the change in Gibb’s free energy of activation shows same mechanism for the hydrolytic reaction in the presence and absence of sodium benzoate. A plausible mechanism is proposed. Keywords: Sodium benzoate, Fuchsin, NaOH, rate law, mechanism

Time course and vectorial nature of albumin metabolism in isolated perfused rabbit PCT

1988 ◽  
Vol 255 (3) ◽  
pp. F520-F528 ◽  
Author(s):  
C. H. Park
Keyword(s):  
Time Course ◽  
Hydrolysis Product ◽  
High Capacity ◽  
Intact Protein ◽  
Renal Metabolism ◽  
First Order ◽  
First Order Kinetics ◽  
Hydrolysis Products ◽  
Renal Tubular ◽  
Hydrolysis Of

The time course and vectorial nature of renal metabolism of albumin (Alb) were studied. The tubular absorption, accumulation, and hydrolysis of Alb and the release of the hydrolysis products were determined in the isolated rabbit proximal convoluted tubule (PCT) perfused with tritiated Alb ([3H3C]Alb) at 36.4 micrograms/ml. The Alb absorption across the apical membrane was constant (99.9 +/- 4.9 x 10(-3) ng.min-1.mm-1). In contrast, the accumulation and hydrolysis of Alb in the cells increased nonlinearly with time. The bulk of the tritium that accumulated in the cells was associated with intact [3H3C]Alb. Only the final hydrolysis products were released from the cells and these first appeared in the peritubular bath 6–7 min after the start of perfusion of the tubule with [3H3C]Alb. The hydrolysis product was not detectable in the tubule lumen. The proteolytic activity correlated linearly with the protein load to the cells, characteristic of first-order kinetics and a high-capacity system. The results suggest that the renal tubular handling of proteins proceeds from the apical to the basolateral aspect of the cell. The transcellular processing of Alb is rapid and can occur in 6–7 min. The accumulation of intact protein in the cell and the first-order kinetics of hydrolysis of the absorbed protein suggest that the rate-limiting step in proximal tubular handling of proteins may include the initial hydrolysis of protein or reside in steps that precede the hydrolysis.

A thermal [1,3] sigmatropic rearrangement: thermolysis of 2,2-bis(ethylthio)-3,3-dimethyl-4-pentenal

1981 ◽  
Vol 59 (21) ◽  
pp. 3120-3122 ◽  
Author(s):  
Gordon S. Bates ◽  
S. Ramaswamy
Keyword(s):  
Solvent Effect ◽  
Wide Temperature Range ◽  
Sigmatropic Rearrangement ◽  
Positive Entropy ◽  
First Order ◽  
Temperature Range ◽  
First Order Kinetics ◽  
Sigmatropic Shift ◽  
Entropy Of Activation

2,2-Bis(ethylthio)-3,3-dimethyl-4-pentenal was found to quantitatively isomerize to 2,2-bis(ethylthio)-5-methyl-4-hexenal over a wide temperature range (130–170 °C). This rearrangement can formally be regarded as a [1,3] sigmatropic shift. The reaction, which could be conveniently monitored by 1Hmr spectroscopy, was found to obey first order kinetics. The substantial positive entropy of activation (+ 61.5 J deg−1 mol−1) for the reaction and the negligible solvent effect (decane vs. DMF) are both consistent with a proposed diradical pathway.

Residue analysis of fosthiazate in cucumber and soil by QuEChERS and GC-MS

2014 ◽  
Vol 68 (10) ◽  
Author(s):  
Min Wu ◽  
Jiye Hu
Keyword(s):  
Solid Phase ◽  
Residue Analysis ◽  
Field Trials ◽  
Residue Level ◽  
Gas Chromatography Mass Spectrometry ◽  
Dispersive Solid Phase Extraction ◽  
First Order ◽  
First Order Kinetics ◽  
Maximum Residue Level ◽  
Relative Standard

AbstractA convenient method was developed for the determination and validation of fosthiazate in cucumber and soil. The procedure is based on liquid partitioning with acetonitrile followed by dispersive solid phase extraction as the clean-up step, after which samples were analysed by gas chromatography-mass spectrometry (GC-MS). The average recoveries ranged from 91.2 % to 99.0 % with relative standard deviations (RSDs) of less than 6.05 %, at three fortification levels (0.02 mg kg−1, 0.1 mg kg−1, 0.5 mg kg−1) in cucumber and soil, and the limits of quantification (LOQs) for fosthiazate were all established at 0.02 mg kg−1. The proposed method was applied successfully to analyses of the dissipation and residue of fosthiazate in field trials. The dissipation rate of fosthiazate was described using pseudo-first-order kinetics with a half-life of 4.33 days and 4.08 days in soil in Beijing and Shandong, respectively. In the terminal residue experiment, fosthiazate residues in cucumber and soil were clearly below the maximum residue level (MRL, 0.2 mg kg−1) set in China.

scholarly journals Synthesis and Characterization of Nanometric Pure Phase SnO2 Obtained from Pyrolysis of Diorganotin(IV) Derivatives of Macrocycles

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
Mala Nath ◽  
P. K. Saini
Keyword(s):  
Particle Size ◽  
Preexponential Factor ◽  
Energy Of Activation ◽  
Activation Free Energy ◽  
First Order Kinetics ◽  
Free Energy Of Activation ◽  
Transmission Electron ◽  
Entropy Of Activation ◽  
20 Nm ◽  
Derivatives Of

Thermal decomposition of diorganotin(IV) derivatives of macrocycles of general formula, R2Sn(L1) and R2Sn(L2) (where R = n-butyl (1/4), methyl (2/5), and phenyl (3/6); H2L1 = 5,12-dioxa-7,14-dimethyl-1,4,8,11-tetraazacyclotetradeca-1,8-diene and H2L2 = 6,14-dioxa-8,16-dimethyl-1,5,9,13-tetraazacyclotetradeca-1,9-diene), provides a simple route to prepare nanometric SnO2 particles. X-ray line broadening shows that the particle size varies in the range of 36–57 nm. The particle size of SnO2 obtained by pyrolysis of 3 and 5 is in the range of 5–20 nm as determined by transmission electron microscope (TEM). The surface morphology of SnO2 particles was determined by scanning electron microscopy (SEM). Mathematical analysis of thermogravimetric analysis (TGA) data shows that the first step of decomposition of compound 4 follows first-order kinetics. The energy of activation (), preexponential factor (A), entropy of activation (), free energy of activation (), and enthalpy of activation () of the first step of decomposition have also been calculated. Me2Sn(L2) and Ph2Sn(L1) are the best precursors among the studied diorganotin(IV) derivatives of macrocycles for the production of nanometric SnO2.

Role of pH on Metribuzin Dissipation in Field Soils

Weed Science ◽  
1976 ◽  
Vol 24 (5) ◽  
pp. 508-511 ◽  
Author(s):  
James S. Ladlie ◽  
William F. Meggitt ◽  
Donald Penner
Keyword(s):  
Soil Ph ◽  
Half Life ◽  
Residue Analysis ◽  
Soil Samples ◽  
First Order ◽  
First Order Kinetics ◽  
Field Soils ◽  
Pseudo First Order

Metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazine-5(4H)one] residue analysis of soil samples showed greater amounts of residue extractable at soil pH 6.7 than 4.6. Metribuzin leaching increased with increasing soil pH. Metribuzin disappearance from soil followed pseudo first-order kinetics. The half-life of metribuzin decreased as soil pH increased and increased at all soil pH levels as depth of sampling increased. The decreased activity and decreased rate of metribuzin dissipation at lower soil pH is apparently due to protonation and increased adsorption.

scholarly journals Acid Hydrolysis of Bis(2,2'; 6',2''–Terpyridyl) Iron(II) Complex in the Water Pools of CTAB/Hexane/Chloroform Reverse Micelles-A Kinetic Study in Confined Medium

2020 ◽  
Vol 15 (3) ◽  
pp. 853-860
Author(s):  
K. V. Nagalakshmi ◽  
P. Shyamala
Keyword(s):  
Ionic Strength ◽  
Acid Hydrolysis ◽  
Reverse Micelles ◽  
Order Rate Constant ◽  
Micellar Medium ◽  
First Order ◽  
First Order Kinetics ◽  
Rate Of Reaction ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of acid hydrolysis of bis(2,2';6',2''–terpyridyl) iron(II) complex has been studied in CTAB/Hexane/Chloroform reverse micelles. The reaction obeys first order kinetics with respect to each of the reactants at all values of W, {W= [H2O]/[CTAB]}. In the reverse micellar medium, the reaction is much slower compared to aqueous medium due to low micropolarity of the water pools which does not facilitate a reaction between reactants of same charge. The effect of variation of W {W=[H2O]/[CTAB]} at constant [CTAB] and variation of [CTAB] at fixed W has been studied. The second order rate constant (k2) of the reaction increases as the value of W increases up to W = 8.88 and remains constant thereafter and it is independent of concentration of [CTAB] at constant W. The variation of rate of reaction with W has been explained by considering variation of micropolarity and ionic strength of water pools of reverse micelles with W. Copyright © 2020 BCREC Group. All rights reserved 

Kinetics of hydrolysis of aromatic mono- and disulfonyl chlorides

1987 ◽  
Vol 65 (9) ◽  
pp. 2263-2267 ◽  
Author(s):  
Przemyslaw Sanecki ◽  
Edward Rokaszewski
Keyword(s):  
Aqueous Acetic Acid ◽  
Polarographic Method ◽  
Acid System ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of Hydrolysis ◽  
Consecutive Reactions ◽  
Pseudo First Order ◽  
Kinetics Of ◽  
Hydrolysis Of

A continuous polarographic method of recording instantaneous concentrations of —SO2Cl groups in an aqueous acetic acid system containing CH3CO2Na has been elaborated. Ten model monosulfonyl chlorides underwent hydrolysis according to pseudo-first order kinetics (20% H2O, 80% v.v. CH3CO2H, 0.5 mol × dm−3 CH3CO2Na). Plots of hydrolysis for seven disulfonyl dichlorides with different number of —CH3 groups have been determined. Pseudo-first order rate constants for two consecutive reactions of hydrolysis (k1 and k2) have been computed and the influence of —SO2Cl and [Formula: see text] groups on the reactivity of the second group —SO2Cl has been discussed. The mechanism of nucleophilic substitution has also been discussed.

Kinetic effects induced by cellulose on water-catalyzed reactions. Hydrolysis of 2,4-dinitrophenyl cellulose xanthate and some sugar xanthate ester analogues

1998 ◽  
Vol 76 (6) ◽  
pp. 960-965 ◽  
Author(s):  
Eduardo Humeres ◽  
Luiz Fernando Sequinel ◽  
Mauricéa Nunes ◽  
Célia MS Oliveira ◽  
Patrick J Barrie
Keyword(s):  
Cellulose Xanthate ◽  
First Order Kinetics ◽  
Acetone Water ◽  
Spontaneous Hydrolysis ◽  
Hydrolysis Of Cellulose ◽  
Entropy Of Activation ◽  
Kinetic Effects ◽  
Catalyzed Reactions ◽  
Parallel Reactions ◽  
Hydrolysis Of

The hydrolysis of 2,4-dinitrophenyl cellulose xanthate (CelXDNP) was studied in 10% v/v aqueous ethanol at 25°C and μ = 0.1 (KCl). The water-catalyzed hydrolysis showed that, as for p-nitrobenzyl cellulose xanthate, it occurs through two parallel reactions with rate constants k'H2O = 4.40 x 10-3 s-1 for the fast hydrolysis, and k''H2O = 6.90 x 10-5 s-1 for the slow hydrolysis. The entropy of activation of the fast hydrolysis was 0.7 ± 1.8 cal K-1 mol-1. External nucleophiles such as hydroxide and simple amines show simple first-order kinetics. The spontaneous hydrolysis of CelXDNP in acetone-water mixtures indicates that the fast reaction does not occur through water polymers and that for water molarity higher than 30 M there are no acetone molecules (or very few) in the highly ordered cybotactic region of cellulose. The spontaneous hydrolysis of methyl 4,6-O-benzylidene- α -D-glucopyranoside 3-(S-p-nitrobenzyl-xanthate) although is faster than the 6-isomer, it is slower than the fast hydrolysis of p-nitrobenzyl cellulose xanthate (CelXNB). Also Δ Sdouble dagger is highly negative (-41.0 cal K-1 mol-1), as it is for alkyl and sugar analogues. Only for the fast hydrolyses of CelXDNP and CelXNB is the entropy of activation almost zero. It is concluded that there is no neighbouring OH effect on the fast hydrolysis of cellulose xanthate esters. Key words: hydrolysis, water catalysis, cellulose xanthate esters, methyl glucose, xanthate esters, neighbouring OH effect.

scholarly journals Mechanisms of thermoinactivation of endoglucanase I from Trichoderma reesei QM 9414

1992 ◽  
Vol 287 (2) ◽  
pp. 583-588 ◽  
Author(s):  
J M Dominguez ◽  
C Acebal ◽  
J Jimenez ◽  
I de la Mata ◽  
R Macarron ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Trichoderma Reesei ◽  
Time Course ◽  
Enzyme Concentration ◽  
Main Process ◽  
Peptide Bonds ◽  
First Order ◽  
First Order Kinetics ◽  
Endoglucanase I ◽  
Hydrolysis Of

The mechanism of irreversible thermoinactivation of endoglucanase I from Trichoderma reesei has been determined at 70 degrees C at the pH of maximum enzyme activity. The time-course of thermoinactivation did not follow first-order kinetics and kinetic constants of the process were dependent on enzyme concentration, suggesting that aggregation was the main process leading to irreversible inactivation. The enzyme was extremely resistant to urea, which in fact seemed to stabilize it against temperature. Disulphide exchange, deamidation and hydrolysis of peptide bonds were also responsible for the loss of enzyme activity at 70 degrees C.

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