Analysis of Pesticides and Insecticides in Fruits, Vegetables and Meat Products of Nepal
Nepal is country which is mainly dependent in Agriculture. People used to grow crops, vegetables, fruits etc and the farmers used to face a lot of problem due to pest. Hence to overcome this issue they use variety of pesticides. Among the pesticides used organophosphate is more popular pesticides and is being used in massive extent. Organophosphates were developed during the second world war and have two main uses: as insecticides and as nerve gases (chemical warfare agents).
They are mostly liquids, liphophilic, with some volatility and a few are solids. Generally, they are less stable and more readily broken down than organochlorines and are relatively short-lived in the environment; hence most of their hazard is associated with short-term (acute) toxicity. The water solubility of the various organophosphate compounds is very variable and they are prepared in numerous formulations: as emulsifiable concentrates for spraying and to control ectoparasites of farm animals (particularly sheep dips) and sometimes internal parasites (such as ox warble fly); as seed dressings and as granular formulations particularly used for the most toxic organophosphates (e.g. disyston and phorate) as the active ingredient is effectively 'locked up' in the granule and is safer to handle and only slowly released into the environment. Organophosphates are also used to control vertebrate pests such as Quelea in Africa.
Organophosphates also act as a neurotoxin. They combine with the enzyme acetylcholinesterase and prevent conduction of nerve impulses at junctions in the nervous system where acetylcholine is the natural transmitter. As a result, acetylcholine builds up in the nerve synapse and eventually leads to synaptic block when the acetylcholine can no longer relay signals across the synapse. In neuro-muscle junctions this leads to tetanus, the muscle is in a fixed state, unable to contract or relax in response to nerve stimulation.
Being a poor country the availability of highly sophisticate analytical is limited. Hence it felt a necessity for us to develop a precise and economic analytical method where the farmers can easily sent their food samples and analyze in low cost.
In the field of pesticides UV-Vis. Spectroscopy play the vital role in the detection and interaction of metal ions with organic ligands i.e. pesticides, especially with transition metal ions. P=O can obscure absorbance. Agents themselves are not significant absorbers or emitters in the UV-Visible spectral region. Hence to analyze the components by uv method chemical derivatization is achieved by using magnesia mixture. To prepare magnesia mixture, solid ammonium chloride is added to aqueous magnesium chloride solution. Boil, cool and add ammonium hydroxide till a strong smell of ammonia is obtained. Soluble Phosphate salts react with magnesia mixture to form white color complex of magnesium ammonium phosphate. The absorbance of thus produced white magnesium ammonium phosphate.is measured spectrophotometrically at a certain wave length that gives maximum absorbance. The intensity of the color is proportional to the amount of phosphate present in the sample solution.