Introduction

Forensic Toxicology is an important discipline of forensic science which deals with the detection and analysis of poisons. Detection of poisons utilizes the application of sequential procedure which involves isolation and extraction of the poisonous substance followed by their separation and analysis using certain sophisticated chromatographic and spectrophotometric techniques. These poisons be it any drug or its metabolite or any pesticide residue because of their tendency of getting deposited into the tissues needs to be isolated from different biological matrixes such as viscera, stomach contents, post mortem blood, serum, urine etc. through various methods (Lanjewar, 2014).

Pesticides are defined as those chemical substances used commonly in agricultural practices to prevent the plants and crops from pests, weeds and other plant diseases. These pesticides being toxic in nature stored in the body of living organisms in fatty tissues and their accumulation increases there over time (Das, 2014). There occurs numerous classes of pesticides based onto the species on which they act. For instance, those which fight against insects are insecticides, similarly those resists fungus are fungicides, and the class of pesticides which prevents the herbs from diseases are known as herbicides and so on. There is another classification which categorize these pesticides on the basis of their chemical nature and function which is organochlorines, organophosphates, carbamates and pyethroids.

These are categorized based on their chemical structure as Organophosphates are the substances that contains phosphate group like Malathion, Dichlorovos, Parathion, Monocrotophos and so on. Similarly Organochlorines are those compounds that contains Chlorine in their structure like DDT, BHC, Eldrin, Endosulfan etc., carbamates are those which are derivatives of Carbamic acid like Carbofuran, Carbryl etc., and Pyrethroids are the ones, which can either be obtained from natural plant source i.e. from Chrysanthemum cinnarefolium or these may be synthetic like Cypermethrin, Fenvalerate, Allethrin and so on.

Since, pesticides gets accumulated in the adipose tissues their determination from the matrix poses a serious challenge because of the interference of the large amount of other analytes and substances that can be co-extracted with these and thereby affects the results of the analysis (Tuzimski, 2012).

The protocol used for the preparation of sample is considered to be the most essential step in the detection of these pesticides so as to maintain the sensitivity of the system. Such extraction methods must be of the type that only the relevant or active component or sample molecule is extracted and the other co- extracts and matrix components gets filtered out (Well, 1988).

Nowadays, technology emerged with the development of large number of advanced and modern methods for the extraction of pesticides which are less time consuming and are efficient in providing the maximum % of recovery without the matrix error. Some of these methods includes Soxhlet extraction, Solid Phase Extraction (SPE), and Accelerated Solvent Extraction (ASE), QuEChERS method of extraction and Supercritical Fluid Extraction etc. (Das, 2014).