Reference laboratory, environmental sampling

A case in which cyanide concentration is higher than the normal reference range (0.02-0.05 /U.g/mL) in whole blood, or cyanide is detected in environmental samples. The case can be confirmed if laboratory testing is not performed because either a predominant... 

Another uncertainty in understanding environmental concentrations arises because of the problem referred to as sampling. Suppose inspectors from the FDA want to know whether a shipment of thousands of heads of lettuce from Mexico contains illegal concentrations of a particular pesticide. Obviously, the entire shipment cannot be sampled, because analysis destroys the lettuce. So the inspector takes a few heads from different areas of the shipment and these are either combined in the laboratory (a composite analysis) or analyzed individually. In either case a certain concentration (for the composite) or a range of concentrations (for the individual heads) is reported from the laboratory. How can the inspector be sure these results fairly represent the entire shipment ... 

With reference to the measurement of artificial and natural radionuclides in environmental samples, activities of the Agency s laboratories in Seibersdorf include the preparation, characterisation, and distribution of reference materials of terrestrial origin, organisation of interlaboratory comparison exercises and proficiency tests, co-ordination of the activities of the ALMERA network, provision of training and expert assistance to scientists from Member States (MS) laboratories, and provision of analytical and radioanalytical support for the benefit of the programmes and projects of the IAEA and its Member States. 

The inter-comparison analysis adopted consists of the sample dividing method and the reference standard sample method . The former method is to divide various environmental samples collected by monitoring laboratories or the hygiene institutes of local government into two parts. One of them is then analysed by such laboratories and the other by JCAC for comparison. The latter method uses reference standard samples which are prepared by JCAC and Japan Isotope Association Corp., by adding appropriate radioactive nuclides to the materials such as aluminum oxide powder or agar. These mock-up samples are analysed by both JCAC and the monitoring laboratories. 

Identification of components in environmental samples and in samples from laboratory studies of biodegradation and biotransformation is generally based on the application of MS coupled to either GC or LC systems. For environmental samples which may contain only small amounts of the relevant compounds, MS is particularly attractive in view of the extremely small amounts of samples — of the order of nanograms — which are required. An important additional advantage is that since the mass spectrometer can be interfaced with GC, LC, or capillary electrophoresis (CE) systems which incorporate separation procedures, pure samples are not required. Some salient issues in MS in the context of environmental application are summarized briefly as an introduction. Reference should be made to an exhaustive review (Burlingame et al. 1998) for instrumental details and aspects that are not covered here, such as MS of synthetic and natural polymers. 

Reference 9 gives a review of applications of atomic absorption spectrophotometry to biological samples. Tiiis technique is widely used for metal analysis in biological fluids and tissues, in environmental samples such as air and water, and in occupational health and safety areas. Routine applications of flame emission spectrometry to biological samples are generally limited to the alkali and alkaline earth metals. Ion-selective electrode measurements (Chapter 13) have largely replaced the flame emission measurements in the clinical chemistry laboratory. 

Zinc is ubiquitous in both the environment and the laboratory. Since many biological and environmental samples contain low levels of zinc, it is easy to contaminate the samples. While analyzing samples, it is imperative that special precautions be taken to avoid sample contamination in order to obtain accurate results and ensure the integrity of the sample. Blood collection tubes are potential sources of zinc contamination (Delves 1981). An example of failure to institute proper measures to control sample contamination, which led to inaccuracies in reported data, was described by Windom et al. (1991). Methods that can be used to avoid reporting erroneous results include interlaboratory data comparison (Galloway et al. 1983) or use of standard reference materials, such as certified SRM 1549 (nonfat powdered milk) available from the National Institute of Standards and Technology (Perry 1990). 

Certified reference materials are intended primarily for calibration and in quality control of analytical techniques. A certified reference material is a reference material, accompanied by a certificate, one or more of whose property values are certified by a procedure that establishes its traceability to an accurate realization of the unit in which the property values are expressed and for which each certified value is accompanied by an uncertainty at a stated level of confidence. They are used to test, validate, and optimize new analytical techniques as well as in quality control of routine laboratory work. Table 3 gives a list of environmental samples that provide certified values of PAH content. These are available from various bodies as certified reference materials. In measuring the concentration of a substance for certification purposes, more than two independent and reliable analytical methods are used. Certified reference materials when used for standardization of analytical methods will make comparisons between PAH data obtained by a variety of workers using... 

The general application of ion chromatography (IC) to environmental samples has been described in a review [1]. More laboratories are looking at speciation as methods are being developed. As well as the traditional ion chromatography companies, most of the inductively coupled plasma mass spectrometry (ICP-MS) companies (PE, Agilent, Thermo, Varian) have done applications or offer speciation columns and/or kits. A website on speciation called Evisa is sponsored by the EU and provides much information (www.spedation.net). There is a links tab that lists various elemental metals, with further Usts of references and certified methods on several different spedes of each particular element... 

Charcoal Tubes Reference has been made earlier to adsorption, which is the property of some solid materials, such as activated charcoal, to physically retain solvent vapors on their surfaces. In environmental health testing, the adsorbed vapors are removed, generally with a solvent, in a laboratory. The solvent is then analyzed by physical methods (gas chromatography, etc.) to determine the individual compounds whose vapors, such as benzene, were present in the sampled air. Industrial atmospheric samples can be collected in small glass tubes (4 mm ID) packed with two sections of activated charcoal, separated and retained with fiberglass plugs. To obtain an air sample, the sealed ends of the tube are broken off, and air is drawn through the charcoal at the rate of 1 liter per minute by means... 

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