Final answer:
The royal blue tube with sodium heparin is used for blood collection and plasma preparation for medical tests. Sodium heparin acts as an anticoagulant to prevent clotting. Plasma separated by centrifugation is then pretreated using various methods for pharmacokinetic studies and detection of specific treatments.
Step-by-step explanation:
The royal blue tube with sodium heparin mentioned in the question is typically used for collecting blood samples in the context of medical laboratory tests where sodium heparin acts as an anticoagulant to prevent clotting.
The blood collected in heparinized tubes is often centrifuged to separate plasma from the cells, a common step for preparing samples for various types of analysis, including measurement of drug levels or metabolic tests.
Sodium heparin ensures that the blood does not clot and thus yields a clear plasma sample upon centrifugation which can then be used for further clinical or pharmacokinetic studies.
For example, plasma pretreatment by Solid Phase Extraction (SPE) using Hydrophilic-Lipophilic Balance (HLB) cartridges, cation-exchange SPE cartridges, or precipitation with acetonitrile (ACN) are methods used to prepare the plasma for analysis of drug substances like lamivudine and isoniazid or to test for substances in the case of cyanide poisoning with treatments like hydroxocobalamin and Sulfanegen TEA.
The use of specific internal standard (IS) compounds, which act as reference markers, such as phenacetin and isoniazid, is also common in the quantification process in tandem with these sample preparation methods.