203 research outputs found

    Predviđanje retencije β-diketonato kompleksa u TLC sistemima na silika-gelu primenom kvantitativnog odnosa strukture i retencije

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    Quantitative structure retention relationships for a series of 30 mixed beta-diketonato complexes of cobalt(III), chromium(III) and ruthenium(III) were derived by multiple linear regression analyses using molecular descriptors obtained by quantum chemical calculations. The retention parameters were obtained by thin layer chromatography on silica gel using mono and two-component solvent systems. The molecular descriptors included in the multiple linear regression analysis were molecular weight, molecular volume, surface area, hydrophilic lipophilic balance, percent hydrophilic surface area, dipole moment, polarizability, refractivity, energy of the highest occupied molecular orbital and energy of the lowest unoccupied molecular orbital. High agreement between the experimental and predicted retention parameters was obtained when polarizability and the hydrophilic lipophilic balance were used as the molecular descriptors. Comparison of the models with those established on polyacrylonitrile showed that the structure of the sorbent is responsible for the chromatographic behaviour of the same compounds. The presented models can be used for the prediction of the retention of new solutes in screening chromatographic systems.U ovom radu kvantifikovan je odnos strukture i retencije 30 mešovitih β-diketonato kompleksa kobalta(III), hroma(III) i rutenijuma(III) primenom multilinearne regresione analize korišćenjem molekulskih deskriptora, koji su dobijeni pomoću kvantno-hemijskih izračunavanja. Retencioni parametri su dobijeni tankoslojnom hromatografijom na silika-gelu primenom mono-i dvokomponetnih rastvarača. Molekulski deskriptori koji su uključeni u multilinearnu regresionu analizu su molekulska težina, molekulska zapremina, površina, hidrofilni-lipofilni balans, procenat hidrofilne površine, dipolni momenat, polarizabilnost, refraktivnost, energija najviše zauzete molekulske orbitale i energija najniže prazne molekulske orbitale. Dobijena je zadovoljavajuća korelacija između eksperimentalnih retencionih parametara i retencionih parametara predviđenih postavljenim modelima, koji sadrže polarizabilnost i hidrofilni-lipofilni balans kao deskriptore. Poređenja ovih modela sa modelima dobijenim na poliakrilonitrilnom sorbentu, za ista jedinjenja, pokazuju da je struktura sorbenta odgovorna za hromatografsko ponašanje. Ovi modeli se mogu koristiti za predviđanje retencije novih jedinjenja u datim hromatografskim sistemima

    Modern analytical techniques in the assessment of the authenticity of Serbian honey

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    Food authenticity in a broader sense means fulfilling chemical and physical criteria prescribed by the proposed legislation. In the case of honey authenticity, two aspects are of major concern: the manufacturing process and the labelling of final products in terms of their geographical and botanical origin. A reliable assessment of honey authenticity has been a long-term preoccupation of chemists-analysts and it usually involves the use of several criteria and chemical markers, as well as a combination of analytical and statistical (chemometric) methods. This paper provides an overview of different criteria and modern methods for the assessment of honey authenticity in the case of a statistically significant number of authentic honey samples of several botanical types from various regions of Serbia

    Predviđanje retencije β-diketonato kompleksa u TLC sistemima na silika-gelu primenom kvantitativnog odnosa strukture i retencije

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    Quantitative structure retention relationships for a series of 30 mixed beta-diketonato complexes of cobalt(III), chromium(III) and ruthenium(III) were derived by multiple linear regression analyses using molecular descriptors obtained by quantum chemical calculations. The retention parameters were obtained by thin layer chromatography on silica gel using mono and two-component solvent systems. The molecular descriptors included in the multiple linear regression analysis were molecular weight, molecular volume, surface area, hydrophilic lipophilic balance, percent hydrophilic surface area, dipole moment, polarizability, refractivity, energy of the highest occupied molecular orbital and energy of the lowest unoccupied molecular orbital. High agreement between the experimental and predicted retention parameters was obtained when polarizability and the hydrophilic lipophilic balance were used as the molecular descriptors. Comparison of the models with those established on polyacrylonitrile showed that the structure of the sorbent is responsible for the chromatographic behaviour of the same compounds. The presented models can be used for the prediction of the retention of new solutes in screening chromatographic systems.U ovom radu kvantifikovan je odnos strukture i retencije 30 mešovitih β-diketonato kompleksa kobalta(III), hroma(III) i rutenijuma(III) primenom multilinearne regresione analize korišćenjem molekulskih deskriptora, koji su dobijeni pomoću kvantno-hemijskih izračunavanja. Retencioni parametri su dobijeni tankoslojnom hromatografijom na silika-gelu primenom mono-i dvokomponetnih rastvarača. Molekulski deskriptori koji su uključeni u multilinearnu regresionu analizu su molekulska težina, molekulska zapremina, površina, hidrofilni-lipofilni balans, procenat hidrofilne površine, dipolni momenat, polarizabilnost, refraktivnost, energija najviše zauzete molekulske orbitale i energija najniže prazne molekulske orbitale. Dobijena je zadovoljavajuća korelacija između eksperimentalnih retencionih parametara i retencionih parametara predviđenih postavljenim modelima, koji sadrže polarizabilnost i hidrofilni-lipofilni balans kao deskriptore. Poređenja ovih modela sa modelima dobijenim na poliakrilonitrilnom sorbentu, za ista jedinjenja, pokazuju da je struktura sorbenta odgovorna za hromatografsko ponašanje. Ovi modeli se mogu koristiti za predviđanje retencije novih jedinjenja u datim hromatografskim sistemima

    Sinteza i karakterizacija kompleksa cink(II), kadmijum(II), platina(II),i paladijum(II) sa kalijum-3-ditiokarboksi-3-aza-5-aminopentanoatom

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    Complexes of zinc(lI), cadmium(II). platinum(lI) and palladium(II) with a new poly-dentate dithiocarbamate ligand, 3-dithiocarboxy-3-aza-5-aminopentanoate (daap(-)), of the type M(daap)(2).nH(2)O (M = Zn(II), Cd(II), n = 2, or M = Pt(II) Pd(II) n = 0). have been prepared and characterized by elemental analysis. IR and UV/VIS spectroscopy, as well as magnetic measurements. The spectra of the complexes suggest a bidentate coordination of the daap- ligand to the metal ions via the sulfur atoms of the deprotonated dithiocarbamato group. The fact that under the same experimental conditions its S-methyl ester does not form complexes could be taken as proof of the suggested coordination mode.Reakcijom između cink(II), kadmijum(II), platina(II) i paladijum(II)-soli i kalijum- 3-ditiokarboksi-3-aza-5-aminopentanoata dobijeni su dogovarajući kompleksi tipa M(daap)2.nH2O. Izolovani kompleksi su okarakterisani elementarnom analizom, IR i UV/VIS spektroskopijom kao i merenjem magnetnih susceptibiliteta. Spektri kompleksa sugerišu bidentatnu koordinaciju daap liganda sa navedenim metalnim jonima preko atoma sumpora deprotonovane ditiokarbamato grupe. Kao dokaz navedenog načina koordinacije može poslužiti činjenica da pri istim eksperimentalnim uslovima S-metil estar liganda ne daje komplekse
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