Solutions of citric acid sodium salts and/or sodium citrate buffer solutions (combination of citric acid and its sodium salts) are often used in clinical laboratories as solutions that inhibit coagulation of blood. Citrate buffer (anticoagulant) in evacuated blood collection tubes consists of different forms of citrate. The determination of citrate is therefore difficult. In this work we optimized the method for the determination of the total concentration of citrate species in aqueous solutions and monitored the quality of selected evacuated blood collection tubes during their shelf life. The suitability of the evacuated blood collection tubes was determined by evaluating two parameters, the draw volume measurement and the determination of the citrate (anticoagulant) concentration. The draw volume of evaluated tubes did not exceed ± 10 % of the indicated value during their shelf life and thus met the specifications. As expected, the draw volume of the evacuated blood collection tubes decreased gradually during their evaluation due to the reduction of the vacuum in the tubes. An increase in the anticoagulant concentration was observed as the draw volume of the tubes decreased.
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