[VIS spectrophotometry used for quantitative determination of iodide in food products of animal origin]. / Spectrofotometria în domeniul vis utilizata la determinarea cantitativa a iodurii din produse alimentare de origine animala.

The spectrophotometric method used in dozing the iodides in the water, has been studied in order to use it in determining the iodides in a series of food products. This method is based on the catalyzed reduction of the iodide of Ce4+ by the arsenious acid. In order to determine the iodide in several food products of animal origin (eggs, milk and meat), the sample is first treated with a concentrated KOH solution and is maintained on a water bath until is obtained a residue; this is then subjected to calcination at temperatures of 500-600 degrees C until a perfectly white ash is obtained. After cooling, the ash is dissolved in water, concentrated H2SO4 is added and is completed with water up to a certain volume. The thus obtained solution is used for determination of the iodide in food, according to the method described above. The content of iodide (microgram%) have been calculated with the relation deduced from the equation of the regression line delineated in VIS at 459 nm. The method is selective and the procedure is widely applicable to the determination of iodide in different food products of animal origin.

[The polarimetric determination of pentavalent vanadium by using quinine chlorohydrate as reagent]. / Determinarea polarimetrica a vanadiului pentavalent utilizând clorhidratul de chinina drept reactiv.

The researches of the authors on the quinine chlorohydrate QH+Cl- and sodium metavanadate (Vv) reaction have led to the elaboration of two methods--a conductometric one and a gravimetric one--of dozing the QH+Cl- and, in general, of any quinine soluble salt with NaVO3. The methods, that have applications in the domain of drugs and is based on the formation of a white precipitate, in which the molar ratio QH+:Vv = 1:1. Since some authors have used quinine as a reagent in order to determine polarimetrically some ions (Ag+ and Cu2+), by taking into consideration the optic activity of quinine, we have aimed at using the formation reaction of QHVO3 for quantitatively determine the Vv with quinine chlorohydrate, by measuring the rotation angle of polarized light alpha both for the excess of QHCl reagent and for the solution obtained by dissolving the QHVO3 precipitate formed within the reaction. For this purpose there has been necessary the construction of two standard scales alpha = f(c) and there has been suggested a working methodology for the dozing of Vv with quinine chlorohydrate or any other of its soluble salts, by using any laboratory polarimeter. The results are satisfactory and depend on the sensitivity of the apparatus.

[UV spectrophotometry used for quantitative determination of oleanolic acid]. / Spectrofotometria în UV utilizata la determinarea cantitativa a acidului oleanolic.

In order to adapt the UV spectrophotometry method to oleanolic acid dosing, absorption spectra within the range from 230 to 350 nm have been determined for both OA systems in glacial acetic acid (lambda max = 256 nm) and OA systems in ethyl alcohol (lambda max = 277 nm). The time stability of oleanolic acid in the presence of the two solvents has also been investigated in this study. Besides, the composition of etalon series and graphical representation of experimental results (n = 6) have been performed. Also, the calculation algorithm was given, the regression lines have been drawn and statistical parameters were calculated to establish the mathematical expression of OA concentration (mg%).