Ondrej Novotny

University of Chemistry and Technology, Prague, Praha, Praha, Czech Republic

Are you Ondrej Novotny?

Claim your profile

Publications (3)3.15 Total impact

  • Source
    [Show abstract] [Hide abstract] ABSTRACT: A series of twelve breast milk samples were analysed by gas chromatography-mass spectrometry (GC/MS) operated in selected ion monitoring mode for 3-chloropropane-1,2-diol (3-MCPD). Whilst none of the samples contained 3-MCPD above the limit of detection of 3 microg kg(-1) milk, all contained high amounts of 3-MCPD esterified with higher fatty acids. The levels of 3-MCPD released by hydrolysis of these esters (bound 3-MCPD) ranged from the limit of detection (300 microg kg(-1), expressed on a fat basis) to 2195 microg kg(-1); with a mean level of bound 3-MCPD of 1014 microg kg(-1), which corresponded to 35.5 microg kg(-1) milk. The presence of bound 3-MCPD was confirmed using orthogonal gas chromatography coupled with high-speed time-of-flight mass spectrometry analysis for four randomly selected breast milk samples. Six breast milks collected from one of the nursing mothers 14-76 days after childbirth contained bound 3-MCPD within the range of 328-2078 microg kg(-1) fat (mean 930 microg kg(-1) fat). The calculated bound 3-MCPD content of these samples was within the range of 6 and 19 microg kg(-1) milk (mean of 12 microg kg(-1) milk). The major types of 3-MCPD esters were the symmetric diesters with lauric, palmitic, and oleic acids, and asymmetric diesters with palmitic acid/oleic acid among which 3-chloro-1,2-propanediol 1,2-dioleate prevailed.
    Full-text · Article · Jul 2008 · Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment
  • Ondrej Novotny · Karel Cejpek · Jan Velisek
    [Show abstract] [Hide abstract] ABSTRACT: The formation of a-hydroxycarbonyl and a-dicarbonyl compounds from monosaccharides (glucose, fructose, arabinose, glyceraldehyde, and 1,3-dihydroxyacetone) was studied in three different model systems comprising an aqueous and alkaline solution of potassium peroxodisulfate (K 2 S 2 0 8), and a solution of sodium hydroxide, respectively. In total, six a-hydroxycarbonyl (in the form of O-ethyloximes) and six a-dicarbonyl compounds (as quinoxaline derivatives) were identified by GC/MS and quantified. Acetoll glycolaldehyde, 1,3-dihydroxyacetone, methylglyoxal, and glyoxal were the most abundant low molecular weight carbonyls. Within the model systems studied, the yield of a-hydroxycarbonyl and a-dicarbonyl compounds was 0.32-4.90% (n/n) and 0.35-9.81% (n/n), respectively. The yield of a-dicarbonyls was higher than that of alpha-hydroxycarbonyis only in aqueous solution of K2S2O8 and in the other two model systems an inverse ratio of these two carbonyl types was found. For the first time, ethylglyoxal was identified as a sugar degradation product and several mechanisms explaining its formation were proposed. The achieved data indicated that low molecular weight a-hydroxycarbonyl and a-dicarbonyl compounds are predominantly formed by a direct retroaldol reaction and alpha- and beta-dicarbonyl cleavage. It was evident that some compounds were produced from the sugar fragmentation products. Thus, isomerisation, reduction of dicarbonyls by formaldehyde (cross-Cannizzaro reaction), and mutual disproportionation are possible reaction pathways participating in the formation of a-hydroxycarbonyl compounds. Oxidation and disproportionation of a-hydroxycarbonyl precursors as well as the aldol condensation of low molecular weight carbonyl species (followed by subsequent reactions) play an important role in the formation of several a-dicarbonyl compounds.
    No preview · Article · Jan 2007 · Czech Journal of Food Sciences
  • Source
    [Show abstract] [Hide abstract] ABSTRACT: We provide here for the first time the evidence that 3-chloropropane-1,2-diol (3-MCPD) occurs in foodstuffs in its free form and also in the form of esters with higher fatty acids. These esters represent a new class of food contaminants as 3-MCPD may be released in vivo by a lipase-catalysed hydrolysis reaction. We analysed 20 samples of selected retail food products for their free and bound 3-MCPD content. All samples contained free 3-MCPD at approximately 9.6-82.7 mug/kg food (3 replications, RSD = 0.4-7.0%). The levels of bound 3-MCPD (monoesters and diesters of 3-MCPD with higher fatty acids) found in the foodstuffs analysed varied between the LOD (1.1 mg per kg of fat) and 36.8 mg/kg fat with RSD = 0.3-3.3%. Five foodstuffs of plant origin processed at high temperatures contained elevated levels of bound 3-MCPD (0.14-6.10 mg/kg). A high level of bound 3-MCPD (0.28 mg/kg) was also found in a sample of pickled fish. Some variables potentially influencing the levels of either free or bound 3-MCPD in foodstuffs were determined (pH, water, chlorides, glycerol, fat and its components) and their significance was discussed.
    Full-text · Article · Oct 2004 · Czech Journal of Food Sciences