Frozen specimen, transportation

Polypropylene and polyethylene containers are usually suitable for specimen transport. Glass should be avoided because of its tendency to break. Polystyrene is also unsuitable because it may crack when frozen. The containers must be leak proof and should have a Teflon-lined screw cap that does not loosen under the variety of temperatures to which the container may be exposed. The materials of both stopper and container must be inert and must not have any effect on the concentration of the analyte. 

In controlling specimen transport, the essential feature is the authority to reject specimens that arrive in the laboratory in an obviously unsatisfactory condition (such as a thawed specimen that should have remained frozen). As with other QC procedures, a small number of problems are expected, but if the error rate gets too large, there is a necessity for systems analysis of transport procedures, with resulting modifications. In tests in which stability is a major problem, the design of specific control procedures appropriate for those tests may be necessary. 

Bone samples for aluminium analysis have been taken from the iliac crest at the time of biopsy or at autopsy (Alfrey et al.. 1976 Maloney et al., 1982) and the specimen placed in an Al-free plastic container. Bone for histological staining is fixed in 10% buffered formalin (Maloney et al., 1982). Crapper et al. (1976) analyzed brain samples from specific areas of the cerebral cortex and from subcortical area. Alfrey et al. (1976) analyzed brain samples from frontal cortex. Whole brain as well as white and grey matter were analyzed. A description of how the specimen was handled before analysis was not provided. Crapper et al. (1976) transported and stored brain samples frozen in Al-free plastic containers and performed dissection from the frozen specimen in a dust-controlled room. All instruments and gloves were rinsed in aluminium-free water. At frequent intervals, this entire procedure was performed on standard homogenized freeze-dried brain powder to ensure little or negligible aluminium contamination. 

For transportation of frozen or refrigerated specimens, a styrofoam container should be used. The container walls should be 1 inch (2.5 cm) thick to provide effective insulation. The container should be vented to prevent buildup of carbon dioxide under pressure and a possible explosion. Sohd carbon dioxide (dry ice) is the most convenient refrigerant material for keeping specimens frozen, and temperatures as low as -70 °C can be achieved. The amount of dry ice required in a container depends on the size of the container and the efficiency of its insulation and the time for which the specimens must be kept frozen. One piece of solid dry ice (about 3 inches x 4 inches x 1 inch) in a container with 1-inch styrofoam walls and a volume of 125 cubic inches (2000 cm ) will maintain a single specimen frozen for 48 hours. 

Some analytes are not stable under certain transport, storage and analytical conditions. Therefore, it is essential to evaluate the stability of an analyte under a variety of conditions. Specimens may be collected with preservatives (e.g. sodium huoride) and stored refrigerated or frozen. During analysis, the addition of an internal standard and/or the use of quahty control samples can be helpful in evaluating the stability of an analyte during the entire analytical procedure. 

A styrofoam box can be used to transport the specimen. Pelleted dry ice that can be heaped up around the specimen container is ideal. Alternatively, broken up dry ice as opposed to large chucks or blocks is preferable. Urine cups with screw on caps make ideal sample collection transport containers. Once tissues are frozen, the cup can be labeled, specimens placed inside, and the lid screwed on securely. The container can then be placed on dry ice for transport to the laboratory. 

In the field of cryotechnology, which includes, for example, transport and storage of liquefied gases or frozen biomedical specimens, aerogel insulation offers numerous... 

For most biochemical determinations one should ask the diagnostic centre for information about specific requirements as to the practice of collecting and transporting material. Especially in the case of enzyme analysis in tissues or cells, one must consult the diagnostic laboratory in advance about the conditions for removal, preparation, storage (usually at -70 °C) and transport of the specimens. If fresh tissue is to be studied, a special, ice-cold buffer must be available. The specimen must be at the laboratory within 2 hours after removal of the tissue. In this material (with intact mitochondrial membranes) substrate oxidation rates and ATP production rates can be measured, as well as single enzyme activities. In frozen tissues only the latter tests can be measured. 

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