Environmental sampling procedures

Y. Zebuelir, C. Naef, D. Broman, K. Eexen, A. Colmsjo and C. Oestman, Sampling techniques and cleanup procedures for some complex environmental samples with respect to PCDDs and PCDPs and other organic contaminants , Chemosphere 19 39-44(1989). 

As a result of limited detector sensitivity, there is often a need for sample concentration when determining trace materials contained in a bulk matrix. The need for such procedures frequently arises in forensic work, environmental samples, blood testing etc. A number of methods have been developed for this purpose and some of those in common use will be described. 

Most statutory toxicity testing is done on individual compounds. In the natural environment, however, organisms are exposed to complex mixtures of pollutants. Toxicity testing procedures are described for environmental samples that contain mixtures of different chemicals. 

Reliable methods are available for determination of nitrosamines, especially volatile nitrosamines, in a variety of foods, environmental samples, commercial products, blood and animal tissues. Reviews of these methods are available (1, 2) and descriptions of some state-of-the-art procedures are included in papers on nitrosamine occurrence in this volume. This paper is not intended to be a comprehensive review of historical developments or of the many variations of procedures... 

Separation and detection methods A survey on determination of tin species in environmental samples has been published by Leroy et al. (1998). A more detailed overview of GS-MS methodology has been published by Morabito et al. 1995) and on sample preparation using supercritical fluid extraction has been described by Bayona (1995)- The techniques are now under control, so that routine procedures are available at a relatively low cost (Leroy et al. 1998). 

In the analysis of complex PAH mixtures obtained from environmental samples, reversed-phase LC-FL typically provides reliable results for only 8-12 major PAHs (Wise et al. 1993a). To increase the number of PAHs determined by LC-FL, a multidimensional LC procedure is used to isolate and enrich specific isomeric PAHs that could not be measured easily in the total PAH fraction because of interferences, low concentrations, and/or low fluorescence sensitivity or selectivity. This multi-dimensional procedure, which has been described previously (Wise et al. 1977 May and Wise 1984 Wise et al. 1993a, 1993b), consists of a normal-phase LC separation of the PAHs based on the number of aromatic carbon atoms in the PAH, thereby providing fractions containing only isomeric PAHs and their alkyl-substituted isomers. These isomeric fractions are then analyzed by reversed-phase LC-FL to separate and quantify the various isomers. 

The activities of enforcement laboratories should not be focused on irrelevant problems. Therefore, a clear definition of the relevant residue is needed. In the crops and food sector, procedures are well established to derive the two residue definitions, one for risk assessment and one for monitoring, from metabolism studies. As far as environmental samples are concerned, there is much potential for improvement. There are no clear criteria as to which metabolites should be included in monitoring and control programs. Additionally, the development of criteria for nonpriority pesticides, e.g., naturally occurring compounds or low-risk products, which can be excluded from monitoring exercises would be helpful for laboratories and evaluators. 

Best practices in the analysis of residues in environmental samples groundwater and soil-water monitoring procedures... 

In general, three kinds of organic conpounds can be distinguished as normal constituents of air or environmental contaminants, requiring different sampling procedures for their analysis substances idiose natural state at atmospheric pressure and aid>ient temperature is that of a gas substances having sufficient vapor pressure to sublime or volatilize into the... 

Cooper EL, Milintawisamai M, Panyatipsakul Y. 1993. Implementation of a radiochemical procedure for the analysis of isotopes of Pu, Am and Cm in food and environmental samples. Sci Total Environ 130/131 177-186. 

Corwen [58] used this method for the analysis of ketones and aldehydes in seawater. Halocarbons were similarly separated from environmental samples by Kaiser and Oliver [59]. There have been many other applications of the technique [60-69]. The major advantage of the headspace method is simplicity in handling the materials. At most, only one chemical, the salt used in the salting-out procedure, needs to be added and in most cases the headspace gas can be injected directly into a gas chromatograph or carbon analyser. On the other hand the concentration of organic materials present is limited by the volume of seawater in the sample bottle. This is very much a batch process. 

The OPCW expert group found however that the procedures for environmental sample analysis were too inflexible to achieve the desired outcome. A separate approach would be needed to enable a system that would provide the necessary level and quality of information, but be practical and also recognise the very infrequent likelihood of a requirement for this capability. Compared to the current OPCW approach to environmental samples, that for biomedical samples would likely use a laboratory with a research rather than a routine focus, the accreditation procedures would be less stringent, and the methods used would focus on high quality results at the lowest limits of detection, rather than high throughput. It is not expected that more than a few laboratories will wish to maintain all or some of the necessary expertise to perform these tasks. 

Valkenburg CA, Munslow WD. 1989. Evaluation of modifications to extraction procedures used in analysis of environmental samples from Superfimd sites. J Assoc Off Anal Chem 72 602-608. 

Immunoaffinity procedures can be performed either on-line or off-line, and can be coupled to chromatographic systems [ 118,119] or even to immunoassays [120]. Many examples can be found in the literature regarding the use of immunoaffinity extraction of drugs and pharmaceuticals from biological matrices, as well as of organic pollutants such as pesticides from environmental samples [115,121-124]. 

First, it must be explained that not all published procedures give details of the detection limits achievable. Where this data is available it is quoted in Table 13.13, and compared to the range of concentrations of organometallic compounds actually encountered in environmental samples. 

As a consequence, for unequivocal identification of the constituents of complex mixtures found in surfactant blends and also in the analyses of surfactants and their metabolites in environmental samples, MS and tandem mass spectrometry (MS-MS) have proved to be more advantageous and are discussed thoroughly in Chapter 2. To optimise the output of reliable results and to save manpower and time certain procedures in sample preconcentration, clean-up and separation prior to MS examinations are inevitable. These are discussed in the present book in more detail in Chapter 3. 

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