Too low or too high of a concentration of anticoagulant in the vacuum tube can cause a deviation of the result and consequently lead to a false interpretation of the blood test. For this reason, it is important that the concentration of the anticoagulant in the vacuum test tube is within the defined range, and that the impurities that affect the functioning of the anticoagulant are in the lowest possible concentrations. In one of the types of vacuum blood collection tubes, citrate acts as an anticoagulant, which is either just sodium citrate or a combination of sodium citrate and citric acid. Citrate binds calcium from the blood and thus prevents blood clotting. Tubes for vacuum blood collection should contain a specific concentration of anticoagulant and a specific under-pressure that determines the volume of blood drawn. In my master's thesis, I evaluated the quality of vacuum blood collection tubes. With different methods of filling the tubes, I wanted to gain insight into the accuracy and repeatability of the amount of anticoagulant that is introduced into the tube during production, gain insight into the drop in vacuum inside the tubes and changes in the anticoagulant concentration over time after the addition of the aspirated volume of blood or water. As expected, the vacuum inside the tube decreased with time, and as a result, the anticoagulant concentration increased. The main source of bias is the imprecise introduction of the amount of anticoagulant during production and the evaporation of the solution from the tubes.
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