Environmental preparative chromatography

HPLC has been used in the extraction and purification of pollutants in environmental and biological samples. Its manifold applications are due to the availability of a number of stationary phases, particularly reversed phase columns of various dimensions. HPLC instruments used for this purpose are similar to the analytical machine but with the use of a different column, which depends on the nature of the pollutants to be extracted and purified. Many of the reports available in the literature deal with the use of HPLC as an extraction and purification technique for environmental and biological samples. For determinations of polar pesticides, HPLC appears to be the most appropriate technique for purification purposes [134, 135]. Smith etal. [136] used low pressure HPLC for the extraction of polychlorinated dibenzofurans and dioxins. Furthermore, Blanch era/. [137] used low pressure HPLC for the purification and extraction of PCBs from shark liver. Similarly, Ramos etal. [138] used the Smith etal. [136] method for the extraction of PCBs in dolphin liver. Bethan etal. [139, 140] used a LiChrosorb 100-Si HPLC column for the extraction of bromocyclen collected from river water and of ck-HCH in marine water. However, HPLC cannot achieve a reputation as the universal and highly applicable extraction technique, due to its low range with regard to preparative chromatography. Therefore, further advancement of the technique is required, especially with regard to the development of preparative columns. 

One of trends of development of thin-layer chromatography implies that replacement of aqueous-organic eluents by micellar surfactants solution. This is reduces the toxicity, flammability, environmental contamination and cost of the mobile phases, reduce sample prepar ation in some cases. 

The need to understand the fate of pesticides in the environment has necessitated the development of analytical methods for the determination of residues in environmental media. Adoption of methods utilizing instrumentation such as gas chro-matography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), liquid chromatography/tandem mass spectrometry (LC/MS/MS), or enzyme-linked immunosorbent assay (ELISA) has allowed the detection of minute amounts of pesticides and their degradation products in environmental samples. Sample preparation techniques such as solid-phase extraction (SPE), accelerated solvent extraction (ASE), or solid-phase microextraction (SPME) have also been important in the development of more reliable and sensitive analytical methods. 

In gc, derivatives are usually prepared to allow or improve the chromatography of the sample. The purpose of derivative preparation in hplc is usually to improve detection, especially when determining traces of solutes in complex matrices, such as biological fluids or environmental samples. 

Thin-layer chromatography (TLC) is one of the most popular and widely used separation techniques because of its ease of use, cost-effectiveness, high sensitivity, speed of separation, as well as its capacity to analyze multiple samples simultaneously. It has been applied to many disciplines including biochemistry [1,2], toxicology [3,4], pharmacology [5,6], environmental science [7], food science [8,9], and chemistry [10,11]. TLC can be used for separation, isolation, identification, and quantification of components in a mixture. It can also be utilized on the preparative scale to isolate an individual component. A large variety of TLC equipment is available and discussed later in this chapter. 

Recently, turbulent flow chromatography (TFC) has shown a great potential for online sample pre-treatment in the analysis of PFCs. Up to now, the use of this technique in food and environmental analysis is scarce, but some successful applications have been developed. Among them, the analysis of PFCs has been carried out in cord blood and also in less invasive human samples, hair and urine. In these works, the main advantages presented were the simplified sample preparation, robustness and sensitivity. In addition in the case of cord blood, a low volume of sample was required. 

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