Environmental issues analytical methods

Welch, M. J., Sniegoski, L. T., Allgood, C. C., and Habrum, M., Hair analysis for drugs of abuse evaluation of analytical methods, environmental issues, and development of reference materials, /. Anal. Toxicol, 17, 389, 1993. 

Morrison, J.F., MacCrehan, W.A., Selavka, C.M., Evaluation of supercritical fluid extraction for the selective recovery of drugs of abuse from hair, 2nd International Meeting on Clinical and Forensic Aspects of Hair Analysis, National Institute on Drug Abuse. Special Publication, submitted, 1995. Welch, M.J., Sniegoski, L.T., Allgood, C.C., Habram M., Hair analysis for drugs of abuse evaluation of analytical methods, environmental issues, and development of reference materials, /. Anal. Toxicol, 17(6), 389-398, 1993. 

The definitions of method detection and quantification limits should be reliable and applicable to a variety of extraction procedures and analytical methods. The issue is of particular importance to the US Environmental Protection Agency (EPA) and also pesticide regulatory and health agencies around the world in risk assessment. The critical question central to risk assessment is assessing the risk posed to a human being from the consumption of foods treated with pesticides, when the amount of the residue present in the food product is reported nondetect (ND) or no detectable residues . 

Elsewhere in The Chemistry of Functional Groups series appears a brief discussion on the stages in the lifetime of chemicals2. Organotin compounds are usually very toxic and they constitute a potential source of harmful pollution with both acute and longterm effects. Increasing concern with environmental and occupational issues has also contributed to the development of analytical methods. Table 1 lists organotin compounds that have found industrial application with references to occupational protection protocols where analytical methods for the particular compound can be found. 

The sustainable management of sediments, in addition to water, soil and sludge environmental matrices, in relation to surfactant regulations, is also an important and relevant issue. The US EPA has recently shown concern regarding the levels of surfactants in sediments and has thus released a Draft Contaminated Sediment Science Plan. In this draft, recommendations for the development of analytical methods and evaluations of the toxicity and risk assessment of Emerging endocrine disrupters like APEOs and their metabolites in sediment samples are outlined. 

As already noted, the chemical composition of petroleum and petroleum products is complex and may change over time following release into the environment. These factors make it essential that the most appropriate analytical methods are selected from a comprehensive hst of methods and techniques that are used for the analysis of environmental samples (Dean, 1998 Miller, 2000 Budde, 2001 Sunahara et al., 2002 Nelson, 2003 Smith and Cresset, 2003). But once a method is selected, it may not be the ultimate answer to solving the problem of identification and, hence, behavior (Patnaik, 2004). There are a significant number of petroleum hydrocarbon-affected sites, and evaluation and remediation of these sites may be difficult because of the complexity of the issues (analytical, scientific, and regulatory not to mention economic) regarding water and soil affected. 

The discipline of analytical chemistry is wide and catholic. It is often difficult for a food chemist to understand the purist concerns of a process control chemist in a pharmaceutical company. The former deals with a complex and variable matrix with many standard analytical methods prescribed by Codex Alimentarius, for which comparability is achieved by strict adherence to the method, and the concept of a true result is of passing interest. Pharmaceuticals, in contrast, have a well-defined matrix, the excipients, and a well-defined analyte (the active) at a concentration that is, in theory, already known. A 100-mg tablet of aspirin, for example, is likely to contain close to 100 mg aspirin, and the analytical methods can be set up on that premise. Some analytical methods are more stable than others, and thus the need to check calibrations is less pressing. Recovery is an issue for many analyses of environmental samples, as is speciation. Any analysis that must... 

Engineered variants of enzymes could be another approach in biosensor design for the discrimination and detection of various enzyme-inhibiting compounds when used in combination with chemometric data analysis using ANN. The crucial issues that should be addressed in the development of new analytical methods are the possibility of simultaneous and discriminative monitoring of several contaminants in a multi-component sample and the conversion of the biosensing systems to marketable devices suitable for large-scale environmental and food applications. 

No analytical method is perfect. Spectral interpretation is still difficult, and standard spectra databases are scarce. The issues of quantification, comparison with data collected by other methods, and scale up are important, especially in spectromi-croscopy studies. Radiation damage and sectioning artifacts can make analysis of susceptible samples difficult. The biggest obstacle to widespread use of NEXAFS spectroscopy, microscopy, and spectromicroscopy in environmental studies remains the extremely limited number of such instruments. Typically, each beamline allocation committee receives 2 or 3 times as many requests for time as is available. Studies, when granted, are usually for 2-5 days every 4-6 months. Thus, scientists have to be very selective about the types of questions and samples that they choose to examine using these techniques. Continued pressure and education from the scientific community will be needed to increase the number of beamlines suitable for NOM studies in the future, even as new synchrotron facilities are planned or built. 

Welch et al. evaluated analytical procedures and environmental issues. They investigated methods for the extraction and detection of cocaine, some of its metabolites, morphine, and codeine from hair. They concluded from a round-robin study that extractions with 0.1 ATHCL are as efficient to remove the target compounds from hair as enzymatic digestion that dissolve the hair. GC/MS with either El or Cl provides accurate determinations of the targeted compounds. External contamination by powdered or vapor-deposited cocaine was incompletely removed by all approaches tested, making it difficult to differentiate incorporated drug from external contamination. This was also proved in extensive laboratory experiments by Wang and Cone. ... 

INDUSTRIAL HYGIENE, ANALYTICAL METHODS AND ENVIRONMENTAL ISSUES... 

The validation of analytical methods for quantification (Section 2.4.2) should be made by spiking relevant environmental samples that may often contain seriously interfering compounds. Cleanup of the samples will reveal the continued existence of such complications, although the question of accessibility of analytes in aged samples is an entirely different issue that cannot be addressed by experiment. Assays of samples containing authentic mixtures are obligatory, but they are not sufficient. 

Compound identification in lEC is accomplished by retention time comparison and coelution and/or incomplete separation of organic acids can be expected due to the low separation efficiency of lEC compared to GC, for example. Organic acid pairs known to coelute are fumaric/acetic acid and also succinic/glycolic acid. " Ideally the identity of a compound should be confirmed with an independent analytical method. It is therefore surprising that only few of the environmental methods listed in Table 13.6 even touch on this issue. ... 

Radionuclide analysis methods are published in analytical chemistry and radiochemistry journals, and in methods manuals issued by nuclear facilities such as government laboratories. For example, the Environmental Measurements Laboratory Procedures manual, HASL-300 (Chieco 1997), is an excellent source. Standard methods for radionuclide analysis (see Section 6.7) are available, and should be used whenever appropriate. If conditions differ from those to which published methods have been applied, radionuclide recovery and decontamination must be tested and additional process steps may have to be inserted. 

Variability Of Blank Responses. In order to limit the discussion, let us focus on water analyses as representative of environmental analyses. In the United Kingdom, the Standing Committee of Analysts of the Department of the Environment issues analytical methods In a series of booklets. Included among these are the Methods for the Examination of Waters and Associated Materials. 10-14) Several of these methods have been evaluated by Individual laboratories to determine the limit of detection based on the variability of the blank and using paired comparisons for blank correction. Published values for the limit of detection for several of these methods are... 

A wide variety of analytical methods have been applied to the detection and identification of GSR. In common with other forensic analyses they can be divided into color (chemical) spot tests for initial screening and instrumental methods. The situation with GSR is complicated by the issues of contamination and by the fact that many of the chemical components seen in GSR may have other innocent or environmental sources. 

Monitoring trace elements in waters by ICP-AES How to avoid spectroscopic interferences is an important issue during the development of any analytical method. Such interference is also important in the application of ICP-EAS. Elements commonly present in environmental samples give rise to difficulties in the determination of other elements at ultratrace concentrations. For simplicity a list of alternative emission lines based on relative differences between intensities of the measured elements and their interferences are omitted in Table 4. 

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