Blood sample collection/storage

Serum isolated from blood samples obtained by venipuncture and collected in glass tubes prepared by centrifugation (10 min, 1600 xg) at room temperature following a clotting period for at least 1 h at room temperature storage at - 18°C or lower (stable for > 1 year). The minimum amount required for analysis is 150 pi. 

Patients need not be fasting. Venous blood should be collected in tubes containing EDTA, oxalate, or fluoride. Sample stability depends on the assay method. Whole blood may be stored at 4 °C for up to 1 week. Above 4 °C, Hb Ai +b increases in a time- and temperature-dependent manner, but Hb Ale is only slightly affected. Storage of samples at -20 °C is not recommended. For most methods, whole blood samples stored at -70 °C are stable for at least 18 months. Heparinized samples should be assayed within 2 days and may not be suitable for some methods of analysis (e.g., electrophoresis). 

Serotonin can be measured in whole blood, serum, platelet-rich plasma, platelet-poor plasma (i.e., platelet-free plasma), isolated platelet pellets, urine, and CSF. Most blood serotonin is stored in the platelets and is easily released during sample preparation. For whole blood serotonin, venous blood (10 mL) is drawn into a tube containing potassium EDTA as an anticoagulant, gently mixed, placed on ice, and transferred to a storage tube. An aliquot of blood is then removed for a platelet count alternatively, a simultaneous EDTA blood sample can be collected. Antioxidants such as ascorbic acid or metabisulfite are conveniently added to the storage tube when a fluorometric detection system is used. Blood serotonin samples are stored frozen at -20 °C, preferably within 2 hours after collection. 

Sampling. A blood sample (1-10 ml) was collected in a EDTA vacutube, mixed thoroughly and frozen (quickly) for storage at -20 °C or transportation. 

FIGURE 28.3 The automated blood sampler and telemetry (ABST) system. 1. Animal cage 2. metabolic collection system 3. Empis infusion pump 4. blood sampling pump 5. refrigerated blood storage unit 6. circular telemetry antenna 7. DSI telemetry receiver. BASi Empis automated infusion system for continuous infusion of inuUn-FITC and PAH for GFR and ERPF measurements. The modified urine collector minimizes feces contamination and provides clinical pathology quality urine samples. Chen et al. (2014). Reproduced with permission from Elsevier. 

The analysis of volatiles presents particular problems. First, many of the compounds of interest occur commonly in laboratories and this necessitates special precautions against contamination and interference. Second, collection, storage, and transport of biological samples must be controlled as far as practicable in order to minimize loss of analyte - quantitative work is futile if very volatile compounds such as propane are encoimtered unless special precautions are taken to prevent the loss of analyte from the sample prior to the analysis. Third, many compounds of interest are excreted imchanged via the lungs and thus blood (and/or other tissues in fatalities), and not urine, is usually the sample of choice. Finally, the interpretation of results can be difficult, especially if legitimate exposure to solvent vapor is a possibility. 

If the analyte is very volatile (e.g., propane or butane) and a quantitative analysis is required, a blood sample should be collected directly into the headspace vial in which the analysis will be carried out. Many other volatile compounds are relatively stable in blood and other tissues if simple precautions are taken. In the case of blood, the container used for the sample should be glass, preferably with a cap lined with metal foil greater losses may occur if plastic containers are used. The tube should be as full as possible and should only be opened when required for analysis and then only when cold (4°C). If the sample volume is limited, it is advisable to select the container to match the volume of blood so that there is minimal headspace. An anticoagulant [sodium ethylenediaminetetraacetate (EDTA) or lithium heparin] should be used. Specimen storage between - 5 and 4°C is recommended and 1% (w/v)... 

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