Study of the application of common yew fruit, Taxus baccata L., as acid-base indicator

Pomoću pH vrijednosti možemo opisati kemijske uvjete u otopini i odrediti točku ekvivalencije. Osim toga, mjerenje pH vrijednosti koristi se i izvan kemijskog laboratorija, primjerice u svrhu poboljšanja kvalitete ljudskog zdravlja možemo provjeriti i kontrolirati pH vrijednost tla, vode ili hrane. U kemiji su najzastupljeniji konvencionalni kiselo-bazni indikatori, a sve se više radi na razvoju prirodnih kiselo-baznih indikatora. Tako pripremljeni indikatori sadrže biljne pigmente koji mijenjaju boju ovisno o pH vrijednosti sredine u kojoj se nalaze. Cilj ovog rada bio je ispitati potencijal primjene bobica šumske tise (Taxus baccata L.) kao kiselo-baznog indikatora u kombinaciji s odabranim otapalima (voda, metanol, etanol i aceton). Naime, bobice šumske tise izrazito su crvene boje i sadrže polifenole i karotenoide, što upućuje na moguću upotrebu kao kiselo-bazni indikator. Rezultati ispitivanja pokazali su vizualno najdojmljivije rezultate pri pH = 14, a aceton se pokazao kao najpogodnije otapalo za pripremu ovih indikatora.Using the pH value, we can describe chemical conditions in solution and determine the equivalence point. pH value measurement is also used outside of chemical laboratory, for example in order to improve the quality of health, we can check and control the pH value of soil, water or food. Conventional acid-base indicators are the ones most commonly used in chemistry, but there is a lot of effort being put in the development of natural acid-base indicators. Indicators prepared in this way contain plant pigments that change colour depending on the pH value their environment. The aim of this work was to examine the potential of yew berries (Taxus baccata L.) as acid-base indicators in combination with selected solvents (water, methanol, ethanol and acetone). Yew berries are bright red and contain polyphenols and carotenoids, which points to their potential use as acid-base indicators. Obtained results showed visually most impressive results at pH = 14, and acetone showed to be the most suitable solvent for preparation of these indicators