The CO2 absorption and liquid scintillation counting (LSC) are methods used in radioactivity monitoring programs of nuclear facilities for 14C measurements due to high number of samples and relatively high expected level of 14C concentration. The paper describes the chemical sample preparation applied to a quality control material (IAEA-C3 Cellulose), in order to evaluate the reproducibility of CO2 absorption method for this type of material. Consequently, in the experiments we used two home-made scintillation cocktails, containing two amines, 2-methoxyethylamine (MEA) and 3-methoxypropyl amine (MPA), which detained CO2 as carbamates. Due to the fact that the material used in the dedicated experiments is cellulose (contained in all vegetable materials), the method can be considered as appropriate for 14C determination from biological and vegetable materials.