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The study of the electrochemical and chemical oxidative degradation of salicylic and acetylsalicylic acid
Tonnerová, Barbora ; Kubíčková, Anna (advisor) ; Křížek, Tomáš (referee)
The aim of this Thesis was to study the degradation of salicylic acid by the electrochemical oxidation. The electrochemical oxidation of salicylic acid was compared to the electrochemical oxidation of acetylsalicylic acid. Two electrochemical cells were tested - batch cell and thin- layer flow-cell. The newly developed and validated method of ultra-high performance liquid chromatography has been used to analyse the degradation products, salicylic acid and acetylsalicylic acid. The optimal analysis was made by the Kinetex column C18 (2,1 x 100 mm; 1,7 µm) and mobile phase with two components - acetonitrile and water with addition of 0,1% formic acid. These two components of the mobile phase were mixed by the gradient program from 10 % to 60 % (v/v) acetonitrile. The mobile phase flow was set to 0,3 ml min-1 and the volume of injection was 2 µl. The detection was performed by photodiode array detector at the wavelength 240 nm. Total time of the analysis was 11 minutes. The electrochemical degradation has been studied by an anodic oxidation in a flow cell with a boron-doped diamond (BDD) anode and a stainless-steel cathode. The samples of salicylic acid and acetylsalicylic acid was dissolved in the ammonium acetate, concentration 200 mmol dm-3 at pH=4,0. The 20 % oxidation rate of salicylic acid was...
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The oxidative degradation study of ticagrelor
Tonnerová, Barbora ; Kubíčková, Anna (advisor) ; Křížek, Tomáš (referee)
Ticagrelor is a platelet aggregation inhibitor drug, used for treatment of patients with acute coronary syndrome. The only active metabolite, a reverse blocator of P2Y12 adenosindiphosphate receptor, is produced by hepatic metabolism. Ticagrelor is soluble in 50 % (vol.) methanol solution. The most efficient separation of ticagrelor using ultrahigh performance liquid chromatography turned out to be in gradient: (0-4 min: 20→80 % A; 4-6 min: 80 % A; 6-6,5 min: 80→20 % A; 6,5-8,5 min: 20 % A; A stands for acetonitrile). Mobile phase is composed of acetonitrile and ammonium acetate buffer (20 mmol·dm-3 and pH 8,0). Reverse stationary phase is Kinetex C18 100A column (100 x 2,1 mm, 1,7 µm; Phenomenex, USA). Retention time of ticagrelor is 4,91 min. The separation method was used to observe the oxidative degradation of ticagrelor. After 7 hours of exposition to hydrogen peroxide solution at 50 řC, 20 % of ticagrelor has degraded. One degradation product was formed at same speed as the degradation of ticagrelor had. Retention time of this degradation product is 3,95 min.
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