Collection and preservation

Each step affects the final result and should be included in any method-validation 

Following the initial and critical step of designing a sampling plan, the implementation of that plan should ensure that a representative sample is collected. The sample must be stored and preserved to maintain the chemical and physical properties that it possessed at the time of collection. 

The sample type, type of containers and their preparation, possible forms of contamination, and preservation methods must be considered to maintain the integrity of the sample. Risk assessors are encouraged to seek the advice of their analytical laboratory during the sampling design stage. 

Additional problems are encountered with petroleum hydrocarbons due to the wide range in volatility, solubility and matrix effects. Knowledge of holding times should also be considered. Likewise, sample handling procedures within the laboratory will have a profound effect on the test result i.e. drying and crushing samples will lose volatile species, whereas a GC characterisation of a wet (as received) soil may sometimes show an unusually high aromatic content due to relative solubility effects. 

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The following sources may be consulted for further details regarding the collection of environmental samples. The paper by Benoit and colleagues provides a good discussion of how easily samples can be contaminated during collection and preservation. 

Searching a crime scene is a complex process (25), involving poHce, crime scene technicians, and forensic scientists. The procedure requires careful documentation, collection, and preservation of the evidence. Trace evidence (26) in criminal investigations typically consists of hairs (27,28) both natural and synthetic fibers (qv) (29,30), fabrics glass (qv) (31,32) plastics (33) sod plant material budding material such as cement (qv), paint (qv), stucco, wood (qv), etc (34), flammable fluid residues (35,36), eg, in arson investigations explosive residues, eg, from bombings (37,38) (see Explosives and propellents), and so on. 

In plasma, Lp(a) moves with a pre-beta-1 mobility (B8, B9) and has been referred to as the sinking pre-beta fraction, as it shares the mobility of VLDL yet does not float at the same density in the ultracentrifuge. Serum electrophoresis followed by a lipid staining with Oil Red O or Fat Red should be a convenient method for detection of elevated Lp(a) levels. Sample collection and preservation are, however, critical parameters in this assay (B26, K9). 

Compounds bearing the functional groups of the present chapter are usually analyzed for the characteristic N heteroatom and less frequently for O. In this section some recent advances in the analysis of these heteroatoms are presented. A critical review appeared of the analysis of the nutrient elements C, N, P and Si, and their speciation in environmental waters, including sample collection and preservation, sample preparation and methods for end analysis5. 

The ability to collect and preserve a sample that is representative of the site is a critically important step (Dean, 2003 Patnaik, 2004). Obtaining representative... 

Although these methods measure different petroleum hydrocarbon categories, there are several basic steps that are common to the analytical processes for all methods, no matter the method type or the environmental matrix. In general, these steps are (1) collection and preservation—requirements specific to environmental matrix and analytes of interest (2) extraction so that separations of the analytes... 

Wll. Winsten, S., Collection and preservation of specimens. Stand. Methods Clin. Chem. 5, 1-17 (1965). 

The objective of the Wood Library-Museum of Anesthesiology is to collect and preserve literature and equipment pertaining to anesthesiology and to make available to the anesthesiology community, others in the medical profession and the public the most comprehensive educational, scientific, and archival resources in anesthesiology... 

An important consideration in sample preservation is the observance of holding time, which is defined by ASTM (ASTM, 1987) as follows The period of time during which a water sample can be stored after collection and preservation without significantly affecting the accuracy of analysis. ... 

Plan for evidence identification, collection, and preservation. On evidence preservation, be aware that some neighboring units may want to clear explosion debris from vital roadways and their unit. Some process instrument electronic records are not retained beyond 6 hours or 24 hours, etc., and they must be secured. 

Retort water collection and preservation poses special problems because of its unusual chemical characteristics. For example, the electrochemical properties of the Fischer assay water collected in this study were pH = 8.95, conductivity = 29,000 fjmho/cm at 25°C, and Eh = —310 mv. The major species in the water are NH4 and HCOa". Con-... 

Errors in chemical analysis are the most obvious source of uncertainty in the modeling of water-rock interactions. The uncertainty may result from incomplete analysis, unreliable sample collection and preservation, or from incorrect interpretation of the data. Incomplete analysis are unfortunately prevalent, elements like aluminum are typically present in very low concentrations and are difficult to... 

It is immediately apparent that the complete automation of this sub-stage is a difficult task. Only in a few instances (e.g. the automatic in vivo determinations described In Chapter 14 and performed with the on-line process analysers dealt with in Chapter 17) is this ideal objective affordable. Much more often, some of the above-mentioned operations involve human participation, although It is still termed automated [1]. Therefore, although many clinical analysers are classed as automatic, the blood and urine samples that they handle are collected and even treated manually before they are placed on the sampler. Such is also the case with automatic off-line water pollutant analysers, also calling for manual collection and preservation of samples. Consequently, the automated sampling concept as used here refers to the Introduction Into the analyser or instrument concerned of a definite portion of sample collected from its source and even treated manually, with the few exceptions stated above. 

Grice, G.D., Harvey, G.R., Bowen, V.T. and Backus, R.H., 1972. The collection and preservation of open ocean marine organisms for pollutant analysis. Bull. Environ. Contam. Toxicol., 7 125—132. 

Syn. Nitric Oxide Nitrous Gas.—Best obtained by the action of copper clippings on moderately strong nitric acid, in the apparatus, p. 46. The metal is dissolved with effervescence, and the gas may be collected and preserved over water. 

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