A role of reductones in the monitoring of sulphur dioxide content in wines during their maturation and storage

The content of free SO2 (1.3-37.9 mg/l and 5.3-19.7 mg/l for 2009 and 2010) and total SO2 (38.3-272.0 mg/l and 52.0-102.1 mg/l for 2009 and 2010) for individual wines was in a broad interval. Results of free SO2 found using the commercial SO2 reagent were higher than our results since the reagent determined not only free SO2 but also reductones. The content of titrated acids was constant with a very moderate time decrease and the values were on average about 9.1-5.3 g/l (2009) and 13.1-7.9 g/l (2010). Similarly, the content of tartaric acid was nearly constant and the values were on average about 2.37-1.47 g/l (2009) and 6.65-2.69 g/l (2010). The percentage ratio of tartaric acid in the content of titrated acids is also constant (average 24.39%-38.6% for individual wines).Eurostars.program [WINEurope E! 4230

Spectrophotometric study of time stability and acid-base characteristics of chelerythrine and dihydrochelerythrine

Časová stabilita, acidobasické a optické vlastnosti dihydrochelerythrinu (DHCHE) v UV-VIS spektrální oblasti byly studovány spektrofotometricky v prostředí voda:methanol a voda:ethanol. DHCHE je stabilní v silně kyselém prostředí (pH < 3) a při vyšších množstvích (60% v/v) alkoholů. Acidobasické characteristiky a UV-VIS spektrální vlastnosti chelerythrinu (CHE) byly studovány ve vodných roztocích v přítomnosti různých koncentrací HCl, HNO3, H2SO4, H3PO4 a jejich směsí. Zřetelné posuny tvorných částí absorbančních-pH (A-pH) křivek do alkalické oblasti byly pozorovány v závislosti na typu a koncentraci inertního elektrolyte (nejvýraznější pro HNO3 a HCl). Odpovídající rovnovážné konstanty pKR+ reakce mezi nabitou iminium Q+ částicí a nenabitou QOH částicí (pseudo-basí, 6-hydroxy-dihydro derivátem) chelerythinu vypočtené pomocí numerické interpretace of A-pH křivek za použití počítačového programu SQUAD-G computer leží v rozsahu 8.51-9.31. Nejvýraznější změny delta pKR+ (0.75 a 0.53) byly pozorovány pro H3PO4 a H2SO4, respective. Primární efekt ionových částic a iontové síly byl potvrzen v přítomnosti přídavků NaCl a KCl. Síla interakcí CHE s biomakromolekulárními sloučeninami (např., peptidy, proteiy, nukleovými kyselinami etc.) může být ovlivněna díky pozorovaným vlivům kationů i anionů inertních elektrolytů na acidobasické chování CHE i DHCHE.Time stability, acid-base and UV-VIS spectral proper ties of dihydrochelerythrine (DHCHE) were studied spectrophotometrically in water:methanol and water:ethanol media. DHCHE is stable in strongly acid milieu (pH < 3) and at the higher amounts (60% v/v) alcohol. Acid-base characteristics and UV-VIS spectral proper ties of chelerythrine (CHE) were studied in aqueous solutions in the presence of different concentrations of HCl, HNO3, H2SO4, H3PO4 and their mixtures. Remarkable shifts of formation par ts of absorbance-pH (A-pH) curves to the alkaline medium were observed depending on the type and concentration of iner t electrolyte (most remarkable for HNO3 and HCl). The corresponding equilibrium constants pKR+ of the transition reaction between charged iminium Q+ and uncharged QOH (pseudo-base, 6-hydroxy-dihydro derivative) forms of chelerythine were calculated using a numerical interpretation of A-pH curves by a SQUAD-G computer program which ranged from 8.51-9.31. The highest changes of deltapKR+ (0.75 and 0.53) were observed for H3PO4 and H2SO4, respectively. The priority effect of ionic species and ionic strength was confirmed in the presence of additions of NaCl and KCl. The strength of interaction of CHE with biomacromolecular compounds (i.e., peptides, proteins, nucleic acids etc.) may be affected because of the observed influence of both cation and anion of the iner t electrolyte on acid-base behavior

Acid-base Behaviour of Sanguinarine and Dihydrosanguinarine

V práci byly sledovány acidobazické a optické vlastnosti sanguinarinu a dihydrosanguinarinu v přítomnosti HCl, HNO3, H2SO4, H3PO4, CAPSO a kyseliny octové. Síla interakcí sanguinarinu s bioakticními sloučeninami může být ovlivněna jak kationty, tak i anionty inertního elektrolytu.Acid-base and optical properties of sanguinarine and dihydrosanguinarine were studied in the presence of HCl, HNO3, H2SO4, H3PO4, CAPSO and acetic acid (HAc) of different concentrations and their mixtures. The equilibrium constants pKR+ of the transition reaction between an iminium cation Q+ of sanguinarine and its uncharged QOH (pseudo-base, 6-hydroxy-dihydroderivative) form were calculated. A numerical interpretation of the A-pH curves by a SQUAD-G computer program was used. Remarkable shifts of formation parts of absorbance-pH (A-pH) curves to alkaline medium were observed. The shifts depend on the type and concentration of inert lectrolyte (the most remarkable for HNO3 and HCl ). The corresponding pKR+ values ranged from 7.21 to 8.16 in the same manner (?pKR+ = 0.81 and 0.73 for HNO3 and HCl, respectively). The priority effect of ionic species and ionic strength was confirmed in the presence of NaCl and KCl. The strength of interaction of SA with bioactive compounds (i.e. receptors, transport roteins, nucleic acids etc.) may be affected because of the observed influence of both cations and anions of the inert electrolytes