Specific environmental sample analysis issues

Decisions made in the design of field study data collection directly and indirectly affect analytical method development. Each sampling matrix will require specific procedures, and methods need to be developed with a view to the nature and scope of field monitoring programs that are or may be required. 

The selection of the target population ( population here is used in the statistical sense of the domain from which the sampling occurs) is dependent on the regulatory question to be addressed. Among the target populations that have been the focus of water monitoring studies are  

The emphasis that the FQPA placed on the assessment of pesticide residues in drinking water, for example, led to the collection and analysis of data on the effects of drinking water treatment processes on pesticide residues. These data were presented to the FIFRA Science Advisory Board to highlight the variability in the effects of treatment on different kinds of pesticides and the products formed and the variability of treatment processes employed at different locations and at different collection time intervals at an individual location. These complexities led to the current proposal 

---

Changes in the focus of SFE can be easily followed through its reported applications. Thus, in 1993 [3], environmental applications prevailed (45.9% versus 21.9% devoted to foods and 11.6% to industrial analyses). By 1996, however, SFE applications to food analysis had risen to 38%, environmental uses fallen to 41% and industrial analyses levelled off at 11% [48]. More recently [17], the extraction of food components (particularly fat) has become one of the major applications of SFE, so much so that the current boom in SF extractor sales has been ascribed to it. The book by Luque de Castro et al. [3] contains comprehensive tables of SFE applications in various fields. Also, one review of SFE in food analysis [148] includes four tables with applications involving the extraction of fat from various types of sample (viz. meat and animal products, fish, cereal, seed and animal feed, plants and vegetables). On a more specific level, Eller and King reviewed determinations of the fat content in foods [149]. Finally, the Analytical Chemistry issues devoted to reviewing techniques provide periodic updates on SFE and SFC [150]. 

CE)] with a sensitive and element-specific atomic detector (usually an atomic absorption, emission or mass spectrometer) have become fundamental tools for speciation analysis, as can be seen in a special journal issue devoted to such application. Some of the hyphenated techniques available for spedes-selective analysis in biological and environmental materials are schematically shown in Figure 1.12. The choice of hyphenated technique depends primarily on the objective of the research. Speciation analysis in environmental and/or biological samples faces two main challenges because of the usually low concentrations of the analytes (below 1 pgg ) and the complexity of the matrix itself. 

---