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Determination of bitrex using ultra-high performance liquid chromatography
Fuková, Kateřina ; Kubíčková, Anna (advisor) ; Křížek, Tomáš (referee)
In this work, a method for the determination of bitrex (denatonium benzoate) using ultra- high performance liquid chromatography was developed. A Kinetex C18 column (Phenomenex) with dimensions of 100×2.1 mm and a particle size of 1.7 μm was used for the determination. A mixture of acetonitrile with 0.1% formic acid (component A) and deionized water with 0.1% formic acid (component B) was used as the mobile phase. The best separation was achieved with the gradient program set: 0-2 min: 20 % → 70 % A (vol. %); 2- 3 min: 70 % A (vol. %); 3-3,5 min: 70 % → 20 % A (vol. %); 3,5-5 min: 20 % A (vol. %). The temperature of the column during the separation was 40 řC and flow rate was 0,3 ml/min. The developed method was partially validated. Repeatability was measured, the linearity of the method was verified for sample injection 1 μl and 5μl. For the same sample injection limit of detection and limit of quantification was determined. Using the developed method, seven real samples containing bitrex were measured. These samples differed in matrix. The samples were five different coolants, glass cleaner and a washing gel for black clothing. In coolant Carline Antifreeze G13 (producer OMA CZ) the concentration of bitrex was set at 23,4 ppm. In coolant CS Antifreeze G 13 (producer CLASSIC Oil) the concentration...
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Chemical aposematism: reactions of predators towards chemical warning signals of prey
Chalušová, Kateřina ; Exnerová, Alice (advisor) ; Kotyková Varadínová, Zuzana (referee)
An aposematism is a type of defence mechanism, by which a prey demonstrates towards predator that it is unpalatable and toxic. The reactions of predators towards chemical warning signals of prey differ due to the quantity and a combination of signals showed by prey, the predator species and its primary orientation. Most of works tested reactions of birds towards gustatory and olfactory stimuli, often in combination with signals from other modalities. Although the birds are predators which orientate primarily visually, olfaction, gustation and chemesthesis significantly helped them with determining unpalatable food. Among other tested predators were fish, amphibians, reptiles, mammals and invertebrates and their reactions towards the same chemicals of prey are noted for comparison. The main chemicals used in the experiments regarding birds were denatonium benzoate (Bitrex), quinin and pyrazines. Predators often showed an aversive behaviour, neophobic reactions, accelerated learning and more effective memorizing of the unpalatable prey if it was presented together with chemical signals. Some of the predators were able to control their toxin intake relative to the amount of toxin ingested or to discriminate between palatable and unpalatable food according to the chemical concentration in it. Key...
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