Introduction heavy metal pollution

Analytical Techniques
The development of new technologies and their implementation in the analysis of pesticides in environmental samples has greatly affected the way we perceive and use pesticides. In the 1940’s, pesticides were perceived as miracle chemicals that gave tremendous gain in crop yields and they were used without adequate regard to health and the environment. At the time, thin layer chromatography (TLC) with semi-quantitative detection was the primary means of analysis. Gas liquid chromatography (GLC or GC) with packed columns became the method of choice as commercial instruments improved and selective quantitative detectors were developed in the late 1950’s, to mid 1960’s. By the time of publication of Rachel Carson’s Silent Spring in 1962, GC was predominant method of pesticide analysis (Hawthorne et al. 1994). When the environmental and ecological impacts of pesticides were come in to lime light, the perception of pesticides began to change. Laws that established regulatory controls on the use of pesticides and their presence in the environment required residue analysis using state-of-the-art instrumentation (Hopper, 1996). With the development of improved capillary columns for GC in the 1970’s, tremendous gains in separation power were achieved and the capabilities of multi-residue methods improved accordingly. During the same time frame, high performance liquid chromatography (HPLC) was commercialized and its implementation in pesticide residue analysis permitted detection of many compounds that were not analysed easily. Through the complementary nature of GC and HPLC, a wide range of pesticides could be analysed and many environmentally safer pesticides were developed and registered using these sophisticated technologies (Richter et al. 1996). Presently potentially advanced and sophisticated pesticide analytical methods such Gas chromatography mass spectrometry (GC-MS) Liquid chromatography mass spectrometry (LC-MS), etc, have been developed and commercialized. Figure 2 represent a schematic representation of pesticide analysis method in environmental samples.
Preparation Sample
Extraction Organic Solvents
Clean-up