Study of the application of selected representatives of the orchid family as acid-base indicator

Rod Phalaenopsis jedan je od najrasprostranjenijih i najduže cvjetajućih rodova porodice Orchidaceae. Osim lijepog izgleda, latice ovoga cvijeta možda bi mogle poslužiti i kao pH indikatori. Određivanje pH vrijednosti provodi se pomoću opće poznatih konvencionalnih kiselo-baznih indikatora, ali u istu svrhu mogu se koristiti i neki biljni materijali. To je moguće zbog prisutnosti raznih pigmenata, poput antocijanina i karotenoida, koji mijenjaju boju ovisno o pH vrijednosti. Cilj ovog rada bio je ispitati mogućnost primjene cvijeta odabranih predstavnika porodice Orchidaceae kao kiselo-baznog indikatora. U tu svrhu korištene su svježe latice Phalaenopsis orhideja u kombinaciji s različitim otapalima (voda, aceton, etanol i metanol). Istraživanjem je utvrđeno da se većina ispitanih latica Phalaenopsis orhideja može koristiti kao alternativni kiselo-bazni indikator. Neki od ispitanih uzoraka dali su dobre rezultate samo u bazičnom mediju, a neki u cijelom pH spektru.The genus Phalaenopsis is one of the most widespread and longest flowering genera of the Orchidaceae family. In addition to their beauty, the petals of this flower could be used as pH indicators. The determination of pH is carried out using commonly known conventional acid-base indicators, but some plant materials may also be used for the same purpose. This is possible due to the presence of various pigments, such as anthocyanins and carotenoids, that change colour depending on the pH value. The aim of this work was to investigate the possibility of using flowers of selected representatives of the Orchidaceae family as an acid-base indicator. For this purpose, fresh Phalaenopsis orchid petals were used in combination with different solvents (water, acetone, ethanol and methanol). The research found that most of the examined Phalaenopsis orchid petals can be used as an alternative acid-base indicator. Some give good result only in the alkaline medium, and some in the entire pH spectrum