Buy Now and Pay in EMI's

PESTICIDES: METHODS OF THEIR RESIDUES ESTIMATION

Beena Kumari, T.S. Kathpal
  • Country of Origin:

  • Imprint:

    NIPA

  • eISBN:

    9789390083367

  • Binding:

    EBook

  • Number Of Pages:

    240

  • Language:

    English

Individual Price: 950.00 INR 855.00 INR + Tax

Add to cart Contact for Institutional Price
 

This book provides the traditional as well as modern analytical techniques used for sample preparation of different matrices for extraction, clean-up, detection and estimation of pesticide residues in soil, water and food commodities. It touches some aspects of most extraction cum clean-up techniques known as Quenchers methods. Brief history of pesticide development, modern pesticides and metabolic pathway of selected xenobiotics from different group of pesticides, imparts information on basic nature of pesticides. The book discusses latest analytical techniques like TLC, GLC, HPLC, HPTLC, super critical extraction and chromatography in simple but vivid manner. The sampling extraction, clean-up and solid phase extraction technique for residue analysis has been explained in the detail. Recently developed multi-residue methods have been outlined in a separate . Help from a number of standard reference books and research papers have given it a modern touch. Additionally a containing glossary of pesticide residue terms can be extremely helpful for a beginner in this fields. The book will provide students with sufficient background for the pesticides, their metabolism and above all various techniques for the estimation of residues of the toxic xenobiotics in all components of the environment. In short the book offers an excellent readable material for a knowledge seeker, may be a student or a research worker. It is that the book will prove highly valuable to all those who are engaged in the area of pesticides."

0 Start Pages

Preface Pesticides are an important component in pest management strategies for food production and public health. Regardless of the method of application, pesticides ultimately reach the soil, which serves as a reservoir for these chemicals. Pesticide in the parent form or in its converted form having toxicological significance is collectively termed as pesticide residues. Pesticide residues are absorbed by plants, enter the food chain and accumulate in human as well as animal body fat. Some residues are carried away by wind in the vapor form to long distances away from the source and then get collected by dust and rain before they are deposited on the ground again. Injudicious and indiscriminate use of these chemicals is responsible for environmental pollution and non-target toxicities. Many problems like persistence of toxic residues in the environment, development of resistance in insect-pests and resurgence of pests are also associated with these toxic chemicals. Pollution of environment poses a threat to the health and wealth of every nation. Consequently it is essential to monitor the levels of organic pollutants in the environment. The problem has further been complicated due to presence of multi-residues in environmental components and food commodities. Residues are inevitable by-product of pesticide use. With the benefits of increased knowledge and experience, it is apparent that these products must no longer be used as they were in the past. All these issues have changed pest control from a simple task in the old days into the complex and publicly-sensitive operation of today. People who develop and supervise modern pest control methods must be highly trained in many areas of pesticide usage. The fact regarding pesticide residues that they are found in all components of the environment is only due to the significant advances in analytical chemistry. The techniques are now so sensitive that detection level that can be reached is equivalent to detecting one teaspoon of salt in one million gallons of water. Residue levels even lower than this can also be detected. The knowledge on the fate of pesticides, after application in the environment is useful to research workers associated with their safe and effective use. It is important to know whether a xenobiotic will persist or it will be inactivated. Frequently persistence is desirable for sustained control. However, for many cases, rapid detoxification of the compound may be desirable to avoid cumulative effects. In recent years, pesticide residue analysis has become the world fastest growing and most rapidly changing subject. Pesticide residue analysis is a highly technical area of research involving costly solvents and sophisticated equipments like GC, HPLC, HPLC-MS, GC-MS etc. Only highly trained personnel can conduct the sensitive analysis of nano and picogram quantities of pesticide residues present in different matrices. Through this book, an attempt has been made to give comprehensive account of methods that are presently being followed for sampling, extraction and estimation of pesticide residues employing different analytical techniques.

 
1 Introduction

Part A 1. Pesticides A pesticideis defined as anysubstance intended for preventing, destroying, attracting, repelling or controlling pests including unwanted species of plant, or animals duringthe production, storage,transportation, distributionand processing of the food, agricultural commodities or animal's feed or which may be administered to the animals for the control of ectoparasites. Pesticides include insecticides, herbicides, fungicides, acaricides, nematicides, etc. According to food and agricultural organization (FAO) 1986, the term pesticidehas been defined as“any substance or mixture of substances intended for preventing or controlling any pest and includes anysubstance or mixture of substances intended for use as plant growth regulator (PGR), defoliant or desiccant. The term excludes fertilizers and antibiotics or other chemicals administered to animals to stimulate their growth or to modify their reproductive behaviour”. Pesticides are the largest group of poisonous substances that are widely broadcast today.

1 - 37 (37 Pages)
INR95.00 INR86.00 + Tax
 
2 Pesticide Metabolism in Insects, Plants and Animals

The knowledge on the fate of pesticides, after application in the environment is useful to research workers associated with their safe and effective use. It is important to know whether a xenobioticwillpersist orwill be inactivated. Frequently persistence is desirable for sustained control. However, for many cases, rapid detoxificationof the compound may be required to avoid cumulative effects. Most of the pesticides are not very soluble in water andtheir oxidation orhydrolysis (or both)leads to formation of polar groups. Such reactions are called primary metabolic reactions, often, but not always. Theproducts ofthese primary reactions undergo secondary changes whereby they are conjugated with endogenous substances to form molecules that are more readily excreted. In higher animals, these changes facilitate the transportation of metabolites of pesticides in blood, which in turn leads to their eventual excretion.

39 - 67 (29 Pages)
INR95.00 INR86.00 + Tax
 
3 Sampling, Extraction and Clean-up

After having performed their function, pesticides in the parent form or in some converted form reach the soil, the ultimate sink for these moieties which are collectively termed as residues. According to FAO 1986, pesticide residue is defined as any substance or mixture of substances in food, agricultural commodities or animal feed resulting from the use of pesticides and includes any specified derivatives such as degradation products, metabolism, reaction products and impurities that are considered to be of toxicological significance. From the soil they move into other segments of the environment. The pesticide residues are absorbed by plants and enter the food chain, where they get concentrated in animal fat. Some residues are carried away by wind in the vapor form, which enables them to be transported to long distances from the source of application and then get collected by dust and rain before they are deposited on the ground again. Pesticide residues also move to aquatic environments through runoff, leaching, and atmosphere disposition.

68 - 94 (27 Pages)
INR95.00 INR86.00 + Tax
 
4 Thin Layer Chromatography (TLC)

Chromatography is an important analytical technique for the separation, isolation and identification of the constituents of a mixture. It is a physical method of separation in which the components to be separated are distributed between two phases; one of these phases consisting a stationary bed of large surface area, the other being a fluid that percolates through or along the stationary bed. All forms of chromatography do have the common features given in this definition. All of them involve the physical movements of the sample across a flat surface (tube like) or through a tube. The stationary phases in all of these possess a large surface area. In all the techniques, the movement of the sample is due to the motion of the fluid/mobile phase. The principle underlying all these methods is the selective retardation of the movement of the components by the stationary phase. These methods result in the production of bands of concentrated components. The basis of naming various chromatographic methods are different:

95 - 106 (12 Pages)
INR95.00 INR86.00 + Tax
 
5 Gas Liquid Chromatography (GC)

Chromatography was first employed by Ramsay (1905) to separate mixtures of gases and vapours. The first scientist to recognize chromatography as an efficient method of separation was the Russian botanist Tswett (1906), who used a simple form of liquid-solid chromatography to separate a number of plant pigments. The colored bands he produced on the adsorbent bed evoked the term chromatography for this type of separation (color writing).Althoughcolor haslittletodo with modern chromatography, the name has persisted and, despite its irrelevance, is still used for all separation techniques that employs the essential requisites for a chromatographic separation,viz. a mobile phase and a stationary phase. Gas-liquid chromatography (GC) was invented by James and Martin (1952) and is a separation technique in which the mobile phase is a gas (usually helium or nitrogen) and the stationary phase is a liquid. In the original columns used by James and Martin, the liquid stationary phase was adsorbed on the surface of an inert support such as Celite (a diatomateous earth) or calcined Celite (a form of brick dust). The support was usually deactivated before use by acid treatment and subsequent reaction with hexamethyldisilazane. The technique was extensively used for the separation of a wide range of volatile substances. Thus, chromatography has been defined as a separation process that is achieved by distributing the components of a mixture between two phases, a stationary phase and a mobile phase. Those components held preferentially in the stationary phase are retained longer in the system than those that are distributed selectively in the mobile phase. As a consequence, solutes are eluted from the system as local concentrations in the mobile phase in the order of their increasing distribution coefficients with respect to the stationary phase.By separating the sample into individual components, it is easier to identify (qualitate) and measure the amount (quantitate) of the various sample components.

107 - 123 (17 Pages)
INR95.00 INR86.00 + Tax
 
6 High Performance Liquid Chromatography (HPLC)

High performance liquid chromatography (HPLC) was developed during late 1960s and early 1970s. Today it is a widely accepted separation technique for both sample analysis and purification in a variety of areas. HPLC, basically a highly improved form of column chromatography and popularly known as liquid chromatography, like other forms of chromatography, whether paper, thin layer or gas chromatography, needs two essential components, the stationary and the mobile phase. It has the unique ability to separate and quantitate residues of polar, non volatile and heat labile chemical compounds. HPLC uses high pressure pumps up to 400 atmospheres that makes it much faster, short and narrow columns packed with micro particulate phase and a detector. To affect a separation, mixture to be analysed is dissolved in a solvent (ideally this solvent is identical to mobile phase) and then forced to flow through analytical column along with mobile phase. In the column the constituents of mixture get resolved and are detected with a suitable detector by a proper choice of column, mobile phase and detector. HPLC is a technique having high degree of versatility. There are several excellent texts published over the last decade which may be consulted for general information on the instrumentation in liquid chromatography

124 - 136 (13 Pages)
INR95.00 INR86.00 + Tax
 
7 Supercritical Fluid Chromatography (SFC)

The phenomenon and behavior of supercritical fluid (SCF) has been the subject of research right from 1800's and suggestion of supercritical fluid chromatography (SFC) came in to exixtence in 1958. Supercritical fluid chromatography (SFC) was first developed in 1960, and that time, it was considered as a science fiction chromatography and a revolutionary separation technique. But its reputation has slowly ebbed over the years and it is now moving forward by leaps and bounds as a stable analytical method with many advantages over the existing chromatographic methods. It is an unit operation that exploits the high dissolving power of fluids at temperature and pressurre above their critical values for extracting analytes from sample matrices.The first commercial packed column of SFC was made available in 1981 and the first commercial capillary column SFC instrument was introduced in 1985. Several refrences are useful for understanding the super critical fluid extraction and super critical fluid chromatography

137 - 144 (8 Pages)
INR95.00 INR86.00 + Tax
 
8 High Performance Thin Layer Chromatography (HPTLC)

In the present era, residue analyst is exposed to array of analytical choice and as per International regualtions, presence of pesticide residues in environmental components and food commodities are becoming more stringent.Generally, multiresidue methods are based on GC equipped with selective detection either electron capture detector, nitrogen phosphorous detector, flame ionization detector etc. One most widely applied technique in pesticide residue analysis is HPLC, equipped with different detectors. Another up-datemethod for confirmation is gas chromatography-mass spectrometry(GCMS)and HPLC-MS applyingparticlebeam or thermo sprayionisationtechnique. Recently one more analytical technique which has gained ground in the field of pesticide residue analysis, is high performance thin layer chromatography (HPTLC).The criteria of good analytical technique like simple, rapid, flexible, versatile, inexpensive, easily documented and validated has been the inherent advantage of HPTLC. Strictly speaking, HPTLC is not different in principleor application from conventional TLC, but due to improvements in materials, its effectiveness has also enhanced.The technique has a potential to operate upto femtogramlevel. HPTLC is a sophisticated and automated form of TLC. It is a technique which can generate about 5000 or more theoretical plates. The high performance in TLC is achieved by optimized plate coating materials, by improved sample application techniques, and by developing newmethods for the development of mobile phase. Thus HPTLC is an instrumental approach at different stages of TLC. A flow chart for HPLC principle is shown in Figure 8.1. The principle of separation is based on adsorption and this leads to easyseparationof isomers, includingchiralcompounds.Main difference between HPTLC and TLC is given in Table 8.1

145 - 154 (10 Pages)
INR95.00 INR86.00 + Tax
 
9 Maximum Residue Limits (MRL)

Crops treated with pesticides invariably contain small amount of these chemicals and the hazard depends on the amount of pesticide residues that remain on the crop and their toxicity. The amount of residue that may remain on crop or food commodity and environmental commodities depend on the nature of pesticides, good agricultural practice, environmental conditions and adoption of safe waiting periods and other perfect methods of storage. As residues are inevitable by product of pesticide use, hence pesticide residue in food commodities and their entry in to food chain has become major cause of concern all over the world. The plant science industry has a responsibility to assist farmers to produce crops that are acceptable to the food chain and consumers alike. It is clear that pesticide residues in farm produce should be kept as low as practicable, and eliminated whenever possible through Good Agricultural Practices (GAP). However, the use of pesticides can be regulated to ensure minimum residues on food which can be considered safe to human consumption and environment as a whole. To regulate pesticide residues to safe levels, a concept was introduced by Joint FAO/WHO Expert Committee on Food Additives (1955) and Codex Alimentarius Commissionwas established in 1964 to implement the Joint FAO/ WHO Food Standard Programmes. The Commission has laid down principles for aiming at the maximum residue limits (Tolerance limits) of pesticide on food commodities. The recommendations are based on:

155 - 171 (17 Pages)
INR95.00 INR86.00 + Tax
 
10 Multiresidue Methods for Estimation of Pesticide Residues

In sub-tropical agro-climatic conditions of India, a variety of insect-pest, weeds and diseases hamper the economic growth of field crops. For effective control of these pests, a number of pesticides including insecticides, fungicides, herbicides and nematicides are to be applied. Estimation technique for single pesticideonly can not be followed for detection of residues of all categories of pesticides. Hence, this constantly expanding use of pesticides on food crops accentuates the need for rapid, precise and sensitive method for determination of pesticide residues of all the major groups of pesticides. In such situation, multi-residue analytical technique can be efficiently followed for detection and estimation of multiresidues of intra and inter class xenobiotics. The purpose of multiresidue analysesistodeterminetheresidues ofas manypesticides as possible withina short period of time even if the recoveries of somecompounds are low. In multiresidue methods the recoveries up to 70% are accepted.The recoveriesless than70%have tobe mentionedspecifically. Multiresidue analysis is relativelymore sensitiveand requires extreme vigilance on the part of the analyst during processingof samples. Additionally, instrument, GLC,need to beequipped withcapillary columnsforhigh resolutionand sophisticated detectorslikeECD, NPDand MSD for detectingmulti-residues of the pesticides. Multiresidue analytical methods/techniques havebeen developed for determination of general pesticide residues for some environmental componentsand differentfood commodities.Criteria formulti-pesticides screening as per California Department of Food and Agriculture (CDFA) are:

172 - 194 (23 Pages)
INR95.00 INR86.00 + Tax
 
11 End Pages

Glossary Glossary of terms relating to pesticides is recommended by International Union of Pure andApplied Chemistry (IUPAC), Holland (1996) and the following definitions of terms are among those, which have been adopted by the Codex Alimentarius Commission. A Abiotic degradation: Degradation of a pesticide via purely physical or chemical mechanisms. Examples include hydrolysis and photolysis. Absorption: Transfer of a component from one phase to another. Movement of a pesticide from the environment (e.g. water, ingested food, leaf surface) across a biological membrane into an organism. Acceptable daily intake (ADI): Estimate of the amount of a pesticide in food and drinking water which can be ingested daily over a lifetime by humans without appreciable health risk. It is usually expressed in milligrams per kilogram of body weight.

 
9cjbsk

Browse Subject

Payment Methods