Organic compounds from environmental water

MC Hennion, P Scribe. Sample handling strategies for the analysis of organic compounds from environmental water samples. In Barcelo D, ed. Environmental Analysis. Techniques, Applications and Quality Assurance. Amsterdam Elsevier, 1998, pp 24-78. 

Schwartzenbach, R. P. and Westhall, H., 1981, Transport of Nonpolar Organic Compounds from Surface Water to Groundwater, Laboratory Sorption Studies Environmental Science and Technology, Vol. 15, pp. 1350-1367. 

An on-line technique coupling preconcentration via a precolumn packed with PGC and LC with a PGC analytical column has been applied to the trace-level determination of some polar and water-soluble organic pollutants from environmental waters.As these analytes are much more retained by the graphite surface than by silica Cig, preconcentration on the PGC precolumn cannot be coupled on-line with a widely used and more efficient Cjg silica analytical columns. In this study, applications were presented for the trace-level determination of 2-chloro-4-aminophenol, chloroanilines, amino-phenols, and cyanuric acid these organic compounds are included in the EC environmental priority pollutant list. The influence of the sample matrix was investigated with drinking and river water samples. 

The focus in Chapters 7 and 8 is on the specific sample preparation approaches available for the extraction of organic compounds from environmental matrices, principally soil and water. Chapter 7 is concerned with the role of Soxhlet, ultrasonic and shake-flask extraction on the removal of organic compounds from solid (soil) matrices. These techniques are contrasted with newer developments in sample preparation for organic compound extraction, namely supercritical fluid extraction, microwave-assisted extraction and pressurized fluid extraction. Chapter 8 is arranged in a similar manner. Initially, details are provided on the use of solvent extraction for organic compounds removal from aqueous samples. This is followed by descriptions of the newer approaches, namely solid-phase extraction and solid-phase microextraction. 

LLE has been used in the past for the extraction of pesticides from environmental water samples [17]. However, its application in the extraction of waste-water samples is scarce due to the low efficiency of extraction, especially for polar analytes. Because of the vast amount of surfactants and natural products present in wastewater samples, emulsions are formed which complicate the process of extraction and lead to low extraction recoveries. However, there have been some useful applications of LLE to wastewater analyses. For example, LLE was found to be effective for the isolation of herbicide and pesticide organic compounds from industrial wastewater samples and also from complex matrices [18]. 

Abiotic transformation of contaminants in subsurface natural waters result mainly from hydrolysis or redox reactions and, to lesser extent, from photolysis reactions. Complexation with natnral or anthropogenic ligands, as well as differential volatilization of organic compounds from multicomponent hquids or mixing with toxic electrolyte aqueous solutions, may also lead to changes in contaminant properties and their environmental effects. Before presenting an overview of the reactions involved in contaminant transformations, we discuss the main chemical and environmental factors that control these processes. 

Concentration Methods. The GCMS analysis of an environmental sample starts with the isolation of the organic compounds from the matrix (air, water, food, etc.) into a form suitable for introduction into the GCMS instrument, typically a solution in a volatile solvent. This concentration step includes essentially three major methods vapor stripping, solvent extraction, and lipophilic adsorption. We have recently reviewed the detailed operation of these methods (Ij, (See also Bellar, Budde and Eichel-berger, this volume) but their general features will be outlined here. 

USEPA (1994). Method 525. 1 Determination of organic compounds in drinking water by liquid-solid extraction and capillary column gas chromatography/mass spectrometry. Environmental Monitoring Systems Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Cincinatti, OH, USA. Available from NTIS, 5285 Port Royal Road, Springfield, VA, USA 22161. 

SPME can be used to extract semivolatile organics from environmental waters and biological matrices as long as the sample is relatively clean. Extraction of semivolatile organic compounds by SPME from dirty matrices is more difficult [134], One strategy for analyzing semivolatiles from dirty matrices is to heat the sample to drive the compound into the sample head-space for SPME sampling another approach is to rinse the fiber to remove nonvolatile compounds before analysis [134],... 

Sample preparation methods involve the extraction of volatile compounds from their matrices. Extraction of organic volatile compounds from environmental matrices has been carried out using gases, liquids, or solids. Nowadays, most sample preparation methods for the analysis of VOCs in water use gases or solids as extracting agents because liquid-liquid extraction methods (LEE) present several disadvantages ... 

Quantitative analysis LC is used for the quantitative determination of components in mixtures, especially for high molecular weight or thermally unstable compounds. It is particularly useful for separating complicated mixtures such as natural products derived from plants or animals and biological samples such as urine and blood. Ion chromatography is used routinely in water analysis. LC with MS detection (LC-MS) is a routine and powerful tool for quantitative analysis of organic compounds in environmental and biological samples. 

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