MICRO-SCALE ZINC DETERMINATION IN A SPECIFIC MEDICINE. This work presents zinc determination in certain medicines that contain zinc oxide and zinc undecylenate. The technique consists of a spectrophotometric micro-scale titration, where EDTA is used as titrant, and xylenol orange as an indicator, in a medium adjusted to pH = 6 with acetic acid and sodium acetate. After each added portion of EDTA, the absorbance value is measured at a selected wavelength, in order to detect the end-point of the spectrophotometric titration. The results already obtained are satisfactory and promote student's interest. An additional contribution intends to propose the use of micro-scale techniques.
<span>En su mayoría, los metales se encuentran en la naturaleza combinados químicamente en forma de minerales; esto es, como sustancias naturales, con una composición química característica, ej.: CaCO3 (calcita, piedra caliza), Al2O3 (corindón), FeS2 (pirita), Cu2O (cuprita), Ca5(PO4)3OH (hidroxiapatita), NaCl (halita), CaSO4 (anhidrita), Be3Al2Si6O18 (berilo).</span>
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