Pressure assisted capillary electrophoresis was applied to determination of acid dissociation constants (pKa) of six widely used triazole fungicides (cyproconazole, epoxiconazole, flusilazole, tebuconazole, penconazole and propiconazole) in aqueous medium. The pKa values were determined from the dependence of effective electrophoretic mobility of the triazole fungicides on p[H(+)] of the background electrolyte (BGE) using non-linear regression analysis. The p[H(+)] was used instead of pH to reflect the increased ionic strength of the strongly acidic BGEs (pH<1.75) as compared to the BGEs at pH equal to or greater than 1.75. Prior to the pKa calculation, the measured effective electrophoretic mobilities were corrected to the reference temperature (25°C) and constant ionic strength (25mM). The regression function was modified to allow the determination of pKa in the BGEs of varying ionic strength. The electrophoretic measurements showed that the above triazole fungicides are very weak bases - their pKa values were found to be in the range 1.05-1.97 and were in a good agreement with the values calculated by SPARC online pKa calculator.

• MeSH
• elektroforéza kapilární metody   MeSH
• elektrolyty MeSH
• epoxidové sloučeniny analýza   MeSH
• fungicidy průmyslové analýza   MeSH
• koncentrace vodíkových iontů MeSH
• osmolární koncentrace MeSH
• silany analýza   MeSH
• tlak MeSH
• triazoly analýza   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Previous studies have shown that a large number of polyvinylchloride (PVC) lid gaskets exceed the existing migration limits for epoxidised soybean oil (ESBO) and correct prediction of ESBO release into food therefore appears to be a difficult issue. ESBO migration from PVC gaskets of metal closures into food simulants and food products from the Czech market is evaluated during a survey in 2009 and subsequently one in 2012 to assess progress in lid manufacturing and official testing conditions. ESBO migration from lids into various food simulants was studied at various temperatures (25, 40 and 60°C) during storage times up to 12 months. ESBO released into food simulants or food products was transmethylated, derivatised and analysed by GC-MS. The levels of ESBO migration in foodstuffs in 2012 exceeded the specific migration limit (SML) in fewer products in comparison with the previous survey. However, most of the products were analysed at a time far from the expiry date and exceedance of the SML at the end of the product shelf life is not therefore excluded. More severe test conditions (60°C for 10 days) for specific migration given by the current European Union legislation (Regulation (EU) No. 10/2011) still seem to be insufficient for the simulation of ESBO migration during long-term storage.

• MeSH
• analýza potravin MeSH
• difuze MeSH
• epoxidové sloučeniny analýza   MeSH
• kontaminace potravin analýza   MeSH
• obaly potravin * MeSH
• plynová chromatografie s hmotnostně spektrometrickou detekcí MeSH
• polyvinylchlorid analýza   MeSH
• sójový olej analýza   MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH