Sample storage biological materials

In the preparation of samples from biological materials, the time between sampling and analysis should be kept as short as possible. For storage times of a few (2 or 3) days, refrigeration at 4°C may be adequate. In favorable cases, holding times can be prolonged by the addition of chemical preservatives (e.g., formalin (formaldehyde, HCHO) and alcohol). Dehydration (by drying, combustion, and lyophili-zation) is also used. 

Iyengar G. 1986. Sampling, storage and pretreatment of biological material. In OTMeill IK, Schuller P, Fishbein L, eds. Some metals As, Be, Cd, Cr, Ni, Pb, Se, Zn. lARC Scientific Publication No. 71. Lyon, France Intemational Agency for Research on Cancer, 141-158. 

Together with details of sample preparation and storage, an appropriate analytical method of known accuracy, precision, and sensitivity must be available for the quantification of the substance in the test solution and in the biological material. If these are lacking it is impossible to determine a true BCF. The use of radiolabelled test substance can facilitate the analysis of water and fish samples. However, unless combined with a specific analytical method, the total radioactivity measurements potentially reflect the presence of parent substance, possible metabolite(s), and possible metabolized carbon, which have been incorporated in the fish tissue in organic molecules. For the determination of a true BCF it is essential to clearly discriminate the parent substance from possible metabolites. If radiolabelled materials are used in the test, it is possible to analyse for total radio label (i.e. parent and metabolites) or the samples may be purified so that the parent compound can be analysed separately. 

Safety, adverse events and reporting of adverse events Sample collection, storage and handling of biological material Bioanalytical data (laboratory phase)... 

Sample collection, storage and handling of biological material... 

Sansoni B and Iyengar GV (1980) Sampling and storage of biological materials for trace element analysis. In Elemental Analysis of Biological Materials, IAEA Tech Rep Ser 197, pp. S7-72. International Atomic Energy Agency, Vienna. 

TABLE 1.1 Sampling and Storage Conditions for Biological Material... 

Most stringent requirements on sampling, sample pretreatment, and sample storage have to be fulfilled in the analysis of biological materials, because physiological concentrations are in the low microgram per liter or submicrogram per liter level. 

Ideally samples should be analyzed in situ or at the site of sampling in the field. If direct measurements are not possible or are too expensive, samples should be analyzed as soon as possible to avoid the need for preservation. However, samples cannot always be analyzed directly and they may have to be stored for so long that preservation is necessary. The preservation of water samples is covered in ISO standard 5667/3 (1985). The preservation methods described in this standard include time limits for sample storage and analysis specifications for container material prevention of exposure to light temperature control (2-5°C) pH control (addition of sulfuric, nitric, or phosphoric acid, or sodium hydroxide) addition of special reagents (e.g., ethylenediaminetetraacetic acid (EDTA), copper sulfate, zinc acetate, formaldehyde) to retard biological activity, hydrolysis of compounds and complexes and measures for reducing volatility of compounds and sorption effects. 

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