الفهرس 
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Abstract
1. 1 Introduction:This study was conducted to investigate the stability of four different pesticides under different environmental conditions, these pesticides are Carbendazim as (Fendozim 50 % WP), Dimethoate as (Agrothoate 40 % EC), Fenitrothion as (Fentroth 40 % EC), and Malathion as (Malathion Extra 57 % EC).
The objective of these investigations was planned to study the following:
a. Effect of storage under Egyptian environmental Conditions on the persistence of Carbendazim, Dimethoate, Fenitrothion, and Malathion in their formulations (Fendozim 50% WP, Agrothoate 40% EC, Fentroth 40% EC, and Malathion Extra 57% EC) respectively.
b. Stability of pesticides used under some Egyptian Environmental factors i.e. Ultraviolet rays and direct sunlight.
c. Studying the Chemical Finger Print i.e. IR, GC/MS, LC/MS for pesticides used.
d. Estimation the relevant Impurities for tested pesticides.
The results obtained could be summarized as follows:
III. X. 1: Studying the Persistence and Distribution of the Active Ingredient (a.i) in its Formulation.
III. X. 1. 1: Storage of Tested Pesticides.
III. X. 1. 1. 1: Storage Stability at Elevated Temperatures.
The pervious results of Carbendazim (Fendozim 50% WP) and Fenitrothion (Fentroth 40 % EC) agree with the tolerance for pesticides formulated according to FAO/ WHO Specification.
It has been found that, Carbendazim (Fendozim 50% WP) and Fenitrothion (Fentroth 40% EC) has good storage properties and its a.i has high stable properties.
These properties could be occurred for many reasons depending on their chemical structure.
Carbendazim is the most stable when storage at all periods because carbendazim have benzimidazole ring which causing high aromaticity of this compound and make it very stable.
Fenitrothion also more stable because its chemical structure contains phenyl ring which causing aromatisty.
But the pervious results of Dimethoate (Agrothoate 40% EC) and Malathion (Malathion Extra 57% EC) shows low stability and less storage properties.
III. X. 1. 2: Effect of Environmental Factors on Fate of Tested Pesticides.
III. X. 1. 2. 1: Effect of Ultra-Violet Rays
The decomposition percentages increased up to 53.603, 81.425, 68.964 and 78.923 % for the Carbendazim, Dimethoate, Fenitrothion and Malathion after exposure to UV rays for 96 hours.
The half-life times of Carbendazim, Dimethoate, Fenitrothion and Malathion were 28.88, 14.62, 28.53 and 10.66 hours respectively, after exposures to UV rays as a thin film in glass surfaces duration of exposure to 96 hours.
The rate of degradation of tested pesticides varied according to their chemical structure and the time of exposure.
III. X. 1. 2. 2: Effect of Direct Sunlight.
The decomposition percentages increased up to 56.085, 94.525, 90.864 and 92.695 % for the Carbendazim, Dimethoate, Fenitrothion and Malathion after exposure to direct sunlight for 96 hours.
It was found that statistically, the half-life times of Carbendazim, Dimethoate, Fenitrothion and Malathion were 12.40, 7.31, 7.42 and 6.67 hours respectively, after exposures to UV rays as a thin film in glass surfaces duration of exposure to 96 hours.
The rate of photodecomposition is positively correlated with the exposure period.
III. X. 2 : Method of Analysis
III. X. 2. 1: Identification of Tested Pesticides by Chemical Finger print.
III. X. 2. 1. 1: Identification of Tested Pesticides by Infra Red (IR).
The IR spectra of Carbendazim (a.i) show:
C-H aromatic (mono substituted benzene) at approximately 741.
C-N aliphatic amines at approximately 1016.
C-N (C=N) at approximately 1629.
C-O esters at approximately 1105.
C-H alkyl (methyl) at approximately 1267.
C-H aromatic (benzene/ sub. Benzene) at approximately 3058.
C-H aromatic C=C at approximately 1442.
N-H secondary amines at approximately 3322.
all these groups are characteristics for carbendazim compound.
The IR spectra of Dimethoate (a.i) show:
P=S (P=S stretching ) at approximately 563.
P-O (P-O asymmetric stretching) at approximately 831.
C=O (aldehyde/ketone) at approximately 1650.
C-S (C-S stretching )at approximately 654.
C-H alkyl (methyl) at approximately 2947.
C-H alkyl methylene at approximately 1436.
N-H secondary amines at approximately 3088.
all these groups are characteristics for dimethoate compound.
The IR spectra of Fenitrothion (a.i) show:
P=S (P=S stretching ) at approximately 721.
P-O (P-O asymmetric stretching) at approximately 824.
C-H aromatic (ortho-disubs. benzene) at approximately 755.
C-H alkyl (methyl) at approximately 2953.
NO2 aromatic nitro at approximately 1521.
C-O ethers (aromatic) at approximately 1239.
all these groups are characteristics for fenitrothion compound.
The IR spectra of Malathion (a.i) show:
P=S (P=S stretching ) at approximately 522.
P-O (P-O asymmetric stretching) at approximately 821.
C-S (C-S stretching )at approximately 656.
C-H alkyl (methyl) at approximately 2983.
C=O Carboxylic acids/derivates (esters) at approximately 1735.
C-O ethers (aliphatic) at approximately 1176.
P–O–C aliphatic asymmetric at approximately 1014.
P-S stretching at approximately 500.
all the above groups are characteristics for malathion compound.
• More important use of the IR spectrum is that it gives structural information about tested pesticides carbendazim, dimethoate, fenitrothion and malathion.
• Finally: Our Ideal Results have been established the functional groups of the carbendazim, dimethoate, fenitrothion and malathion structures.
III. X. 2. 1. 2: Identification of Tested Pesticides by Liquid chromatography-Mass Spectroscopy (LC/MS).
Carbendazim can not be determined directly by GC/MS because of their poor volatility, high polarity, and /or thermal stability has grown dramatically in the last few years, thus, the complementary use of liquid chromatography (LC) coupled with mass spectrometry (MS) may be used for future analysis of carbendazim.
Consequently, LC-MS is gaining acceptance for carbendazim with the ready availability in recent years of atmospheric –pressure chemical ionization (APCI), LC-MS interfaces such as atmospheric pressure chemical ionization (APCI) and electrospray (ES) Provide structural information and sensitivity and over come the limitation of other LC device LC-MS allows the conformation and quantitation of highly polar, less volatile and thermally labile compounds.
Table (1-1) : Retention time and mass spectral data of Carbendazim
Compound Retention time MS spectral data (m/z relative intensity )
Carbendazim 8.6 192.2 (M+1) , 160.1
Finally: Our Ideal Results have been established the Molecular Weight (M. WT) of Carbendazim.
III. X. 2. 1. 3: Identification of Tested Pesticides by Gas chromatography-Mass Spectroscopy (GC/MS).
III. 1. 2. 1. 3: Identification of Dimethoate by GC/MS.
• The spectral data for dimethoate was given in Table (1-2).
Table (1-2): Retention time and Mass spectral data of Dimethoate.
Compound Retention time (min) MS spectral data
(m/z relative intensity)
dimethoate 17.449 229, 212, 198, 182, 171, 157, 143, 125, 104, 87, 73, 58
III. 2. 2. 1. 3: Identification of Fenitrothion by GC/MS.
• The spectral data for fenitrothion was given in Table (1-3).
Table (1-3): Retention time and Mass spectral data of Fenitrothion.
Compound Retention time (min) MS spectral data(m/z )relative intensity
fenitrothion 20.249 277, 260, 246, 228, 214, 200, 182, 169, 150, 136, 125, 109, 93, 79, 63, 51
III. 3. 2. 1. 3: Identification of Malathion by GC/MS.
• The spectral data for malathion was given in Table (1- 4).
Table (1-4): Retention time and Mass spectral data of Malathion.
Compound Retention time (min) MS spectral data(m/z )relative intensity
malathion 20.505 331 (M+,1), 285, 271, 256, 238, 224, 211, 189, 173, 158, 143, 125, 111, 93, 79, 55
It Can be Conciliated that:
Our results were acquired under good laboratory practices and respected strict protocols.
Use of GC-MS enabled rapid and efficient identification, separation, and quantitative determination of dimethoate, fenitrothion, and malathion.
This technique has been demonstrated to be adequate for confirming the detection dimethoate, fenitrothion, and malathion.
Finally: Our Ideal Results have been established the Molecular Weight of the dimethoate, fenitrothion, and malathion.
III. X. 3: Estimation of Relevant Impurities.
III. X. 3. 1: Estimation of Impurities Relevant to Storage Tested Pesticides.
III. X. 3. 1. 1: Estimation of Impurities Relevant to Storage Tested Pesticides at Elevated Temperatures.
III. 1. 3. 1. 1: Estimation of Impurities Relevant to Storage Wettable Powder Pesticides at Elevated Temperatures.
e.g. Carbendazim
• The amount of 2,3 diaminophenazine was 16.48, 15.92, 15.28, 14.86 and 14.73 g/kg after storage at elevated temperature 54 ±2 0C for 14 days; 45 ±2 0C for 6 weeks; 40 ±2 0C for 8 weeks; 35 ±2 0C for 12 weeks; 30 ±2 0C for 18 weeks.
• Variation in temperature degrees affected on increasing the impurities in carbendazim, from the previously results we found that the amount of impurities in carbendazim increased by storage at elevated temperature at 54 0C ±2, 45 ±2 0C, 40 ±2 0C, 35 ±2 0C and 30 ±2 0C.
III. 2. 3. 1. 1: Estimation of Impurities Relevant to Storage Emulsifable Concentrates Pesticides at Elevated Temperatures.
e.g. Dimethoate.
• The data shows that the amount of isodimethoate increased by increasing the storage at elevated temperatures to become 5.27, 4.93, 4.24, 3.58 and 2.83 % after storage at 54 ±2 0C for 14 days; 45 ±2 0C for 6 weeks; 40 ±2 0C for 8 weeks; 35 ±2 0C for 12 weeks; 30 ±2 0C for 18 weeks.
• The data shows that the amount of omethoate increased by increasing the storage at elevated temperatures to become 6.73, 6.32, 6.01, 4.50 and 1.93% after storage at 54 ±2 0C for 14 days; 45 ±2 0C for 6 weeks; 40 ±2 0C for 8 weeks; 35 ±2 0C for 12 weeks; 30 ±2 0C for 18 weeks.
• Dimethoate is an organophosphorus pesticide, so it is normally stable at ambient temperatures, but at elevated temperatures, good yield of isomers may be obtained. In case of dimethoate, Dimethoate will degrade into the corresponding S-methyl isomer (isodimethoate). The S-methyl isomer has proven toxic to mammals and, hence, it is undesirable in the final formulation.
e.g.: Fenitrothion.
• The data shows that the amount of S-methyl fenitrothion increased by increasing the storage at elevated temperatures to become 1.81, 1.80, 1.62, 1.56 and 1.54 % after storage at 54 ±2 0C for 14 days; 45 ±2 0C for 6 weeks; 40 ±2 0C for 8 weeks; 35 ±2 0C for 12 weeks; 30 ±2 0C for 18 weeks.
• Fenitrothion is a phosphorothionate and other compounds of this type are known to have the potential to isomerize in storage, to form a potentially more toxic S-alkyl isomer.
• S-methyl fenitrothion can increase in concentration during storage of fenitrothion TC or formulations in the presence of compounds such as anionic surfactants and at elevated temperatures. A small increase in S-methyl fenitrothion concentration was found in the formulations during the CIPAC storage test at 540C for 14 days.
• The higher temperatures are such that they rarely are attained in practice although summer day time maximum temperatures > 500C are possible in storage buildings in tropical countries. For practical purposes, this is normally considered to be the most stringent test of storage stability.
e.g.: Malathion.
• The data shows that the amount of malaoxon increased by increasing the storage at elevated temperatures to become 0.641, 0.625, 0.599, 0.495 and 0.471% after storage at 54 ±2 0C for 14 days; 45 ±2 0C for 6 weeks; 40 ±2 0C for 8 weeks; 35 ±2 0C for 12 weeks; 30 ±2 0C for 18 weeks.
• Two parameters cause increasing the amount of isomalathion, one is the elevated temperatures and the other is the long storage periods, the data shows increasing the amount of isomalathion with increasing storage at elevated temperatures to become 0.218, 0.215, 0.206 after storage at 54 ±2 0C for 14 days; 45 ±2 0C for 6 weeks; 40 ±2 0C for 8 weeks, also the data shows increasing the amount of isomalathion with increasing the storage to long periods to become 0.233 , 0.231after storage at 35 ±2 0C for 12 weeks and at 30 ±2 0C for 18 weeks respectively.
• The data shows that the amount of MeOOSPS-triester increased by increasing the storage at elevated temperatures to become 0.531, 0.485, 0.476, 0.420 and 0.356 % after storage at 54 ±2 0C for 14 days; 45 ±2 0C for 6 weeks; 40 ±2 0C for 8 weeks; 35 ±2 0C for 12 weeks; 30 ±2 0C for 18 weeks.
• The data shows that the amount of MeOOOSPS-triester is undetectable.
• malathion is the fastest affected by thermal conditions, in case of malathion the P = S (thiono) linage may isomerizes to the P-S (thiolo) form and the product may be substantially more toxic to mammals. The toxicity of malathion to human is quite low, but the presence of more than 2% of isomalathion, the S-methyl isomer, in manufactured product used for malaria control led to an outbreak of poisoning among 7500 workers.
III. X. 3. 1. 2: Estimation of Impurities Relevant to Exposure Tested Pesticides to Ultraviolet Rays.
III. 1. 3. 1. 2: Estimation of Impurities Relevant to Exposure Wettable Powder Pesticides to Ultraviolet Rays.
e.g. Carbendazim
• When pesticide was exposure to ultraviolet rays or direct Sunlight the active ingredient of the compound is decompose into its main impurities until the active ingredient disappear at the long period exposure and the pesticide degraded to another compounds among them their impurities, so we find at long periods the amount of impurities are very high. So the amount of impurity (2,3 diaminophenazine) becomes very high at the end of exposure periods to Ultraviolet ray or direct Sunlight.
• The amount of 2,3 diaminophenazine was 33.17 g/kg at the end of exposure period to ultraviolet rays (96 hours).
III. 2. 3. 1. 2: Estimation of Impurities Relevant to Exposure Emulsifable Concentrates Pesticides to Ultraviolet Rays. e.g. Dimethoate.
• The data shows that the amount of isodimethoate increased by increasing the exposure periods to ultraviolet rays to become UND, 9.68, 10.24, 10.64, 14.15, 16.04 and 22.37% after exposure 1, 2, 6, 12, 24, 48, and 96 hours to ultraviolet rays.
• The amount of Omethoate was undetectable.
e.g. Fenitrothion.
• The data shows that the amount of S-methyl fenitrothion after 12 hours becomes17.74% and becomes 17.97, 25.19, 30.86% after exposure 24, 48 and 96 hours to ultraviolet rays.
• The amount of TMPP undetectable.
e.g. Malathion.
• The amount of malaoxon becomes 2.16, 2.50, 5.64, 7.03 and 22.05% after 6, 12, 24, 48 and 96 hours to exposure to ultraviolet rays.
• The amount of isomalathion becomes 2.60, 3.03 and 22.19% after 24, 48 and 96 hours to exposure to ultraviolet rays.
• The amount of MeOOSPS-triester undetectable.
• The amount of MeOOOSPS-triester was 0.93, 0.944, 0.945, 0.97, 1.077, 1.09 and 3.45% after exposure 1, 2, 6, 12, 24, 48 and 96 hours to ultraviolet rays.
• In the environment, the thiophophoryl bond (P=S) of malathion can be oxidized to their corresponding (P=O) oxon by various oxidizing agents such as ozone, dinitrogen tetroxide, peracid and chlorine.
• in the atmospheric, gas-phase malathion can be oxidized to malaoxon by atmospheric oxidants such as ozone, nitrate, radicals and OH radicals
III. X. 3. 1. 3: Estimation of Impurities Relevant to Exposure Tested Pesticides to Direct Sunlight.
III. 1. 3. 1. 3: Estimation of Impurities Relevant to Exposure Wettable Powder Pesticides to Direct Sunlight.
e.g. Carbendazim
• at the end of exposure period to direct sunlight the amount of 2,3 diaminophenazine becomes very high to reach to 42.86 and 63.08 g/kg after 48 and 96 hours from exposure to direct sunlight.
III. 2. 3. 1. 3: Estimation of Impurities Relevant to Exposure Emulsifable Concentrates Pesticides to Direct Sunlight.
e.g. Dimethoate.
• At the end of storage period (96 hours) the amount of isodimethoate and omethoate becomes very high to become 95.5% for isodimethoate and 63.15% for omethoate.
e.g. Fenitrothion.
• The data shows that the amount of S-methyl fenitrothion was15.43, 16.33, 17.51, 21.32 and 68.87% after exposure 6, 12, 24, 48 and 96 hours to direct sunlight.
• The amount of TMPP undetectable.
e.g. Malathion
• The amount of malaoxon was 2.75, 5.66, 6.05, 6.48 and 7.81% after 6, 12, 24, 48 and 96 hours from exposure to direct sunlight.
• The amount of isomalathion was 15.58 % at the end of exposure period (96 hours) to direct sunlight.
• The amount of MeOOSPS-triester undetectable.
• The amount of MeOOOSPS-triester was 5.94 % at the end of exposure period (96 hours) to direct sunlight.
from all results we can conclude that: The amount of impurities are increased by increasing storage at (elevated temperatures, ultraviolet rays and direct sunlight).