Handling Biological Materials

Sample handling is always a crucial part of analysis. In the biomedical field, there are several issues not conunonly encountered in general analytical work, and these will be described in this section. Biological materials are potentially hazardous  

Sample collection may be noninvasive (e.g., urine, feces, sputum, collection of exfoliated cells with buccal swab) or invasive (e.g., blood taking and biopsy). The measured parameter may show time dependence in such cases the sample should be taken at various intervals and the time course of the parameter (such as drug clearance) should be determined. Biological fluids are (in most cases) homogenous. For nonhomogenous samples (such as tissues), it is important to estabhsh that the sample taken is representative and for all persons involved in the study the same type (or same fraction) of sample is studied. 

To cite a few examples, anticoagulants must nearly always be added to the blood sample. There are various anticoagulants, for example, heparin, citrates, or EDTA. Best quality of RNA and DNA samples may be obtained from citrate-stabilized blood, but it may lead to a higher yield of lymphocytes for culture. On the contrary, heparin-stabilized blood could influence T-cell proliferation, and moreover heparin binds to many proteins and may therefore compromise proteomic studies. EDTA is suitable for both DNA assays and proteomics, but it affects Mg concentration causing problems for cytogenetic analyses (e.g., decreases mitotic index). 

The intended storage time also influences what temperature should be considered optimal. Isolated DNA may be stored at 4°C for several weeks, at -20°C for several months, and at —80°C for several years. On the contrary, isolated RNA should always be kept at — 80°C. Live cells are stable at room temperature up to 48 h, but after that they must be either cultured or cryopreserved in liquid nitrogen at — 150°C in order to remain aUve. Since serum and plasma contain a large amount of soluble molecules, it should be kept at very low temperature (-80°C) to remain intact. At this temperature, plasma is regarded stable (in most respects) for several years. 

Proteins are sensitive to degradation by proteases thus, if the cells are damaged the result of the assay may be misleading. To avoid this problem the proteins 

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The stability of a reference material is of great importance since the same material may be used over a period of many years. At issue is not only the question of whether it continues to be pleasant to handle (biological materials can of course be attacked by bacteria, fungi, insects and other pests), but also that, due to evaporation or chemical reactions, the concentrations and chemical binding of some of the elements of interest may change. This is obviously of greatest concern for elements that can exist in a volatile form such as mercury and arsenic, which could thereby be lost. 

Fried, B. (1993). Obtaining and handling biological materials and prefractioning extracts for lipid analyses. In Handbook of Chromatography—Analysis of Lipids, K. D. Mukherjee and N. Weber (Eds.). CRC Press, Boca Raton, FL, pp. 1-10. 

Recent reviews on sample preparation include that of Christie (70a) on obtaining lipid extracts from tissues and that of Fried (70b) on obtaining and handling biological materials and prefractionating extracts for lipid analyses. Chapter 2 in Hammond (la) also provides detailed descriptions on lipid extraction of photosynthetic tissue, oilseeds, tiger prawns (crustaceans), coffee whitener, wheat flour, spores, and volatile fatty acids from cells grown in culture media. 

As pointed out in Section 4.3.2, containment is the most important practice when handling biological materials. To achieve containment requires strict adherence to standard microbiological practices and techniques. Failure to follow these standard practices can result in laboratory-acquired infections (LAIs) as illustrated in Incidents 4.3.2.1, 4.3.2.2, 7.3.4.1, and 7.3.4.2. 

Handling biological material always raises the issue of safety for the persoimel involved. Chemical hazards and safety procedures relating to these are well known for chemists. Regarding biological hazards, first the staff participating in the research should be aware of them, and second, adequate precautions should be taken and the personnel should be trained on how to handle human samples safely. 

Laboratories handling biologicals have their own special problems. They often have to dispose of small but significant amounts of materials that may be very hazardous. Every laboratory procedure must then be scrutinized with this in mind. 

Diselenophosphate complexes are prepared from the interaction of metal salts and complexes with appropriate diselenophosphoric acid or its salt. The acids are obtained from the reaction of phosphorus(V) selenide with alcohols 229). The preparation of phosphorus(V) selenide and its reactions with alcohols 229) and amines 22°) have been described and a variety of complexes reported (Table 4). The biological activity of these compounds does not seem to have described but the exercise of extreme caution when handling these materials is recommended. Zingaro and his coworkers 229-232) thoroughly characterized the thermal and spectroscopic properties of a number of compounds. 

The publisher cannot assume any legal responsibility for given data, especially as far as directions for the use and the handling of chemicals and biological material are concerned. This information can be obtained from the instructions on safe laboratory practice and from the manufacturers of chemicals and laboratory equipment. 

Many of the problems encountered in the processing of biological materials are similar to those found in other areas of chemical engineering, and the separation processes used are frequently developments from counterparts in the chemical industry. However, biological materials frequently have rheological properties which make then difficult to handle, and the fact that their density differs little from that of water and the interfacial tensions are low can give rise to difficulties in physical separation of product. 

RSH groups are not easy to assay. Some arise during the handling of the biological material before the measurements are made and some arise from the lack of specificity of many reagents used as probes for quantitation of sulphydryl compounds (reviewed in Russo and Bump, 1989). 

A precondition for miniatiuization of the assay volume to a few microliter is the availability of reliable and versatile liquid-handling tools for precise metering and delivery of microliter and nanoliter aliquots of compound solutions, assay reagents, and biological materials. Low-volume liquid handlers in the life sciences utilize a variety of basic microfluidic methods for precise dosage of the aliquot volume being transferred, including ... 

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