Djura Vujic

Comparing sugar components of cereal and pseudocereal flour by GC-MS analysis.

Gas chromatography with mass spectrometry was used for carrying out a qualitative analysis of the ethanol soluble flour extract of different types of cereals bread wheat and spelt and pseudocereals (amaranth and buckwheat). TMSI (trimethylsilylimidazole) was used as a reagent for the derivatisation of carbohydrates into trimethylsilyl ethers. All samples were first defatted with hexane. (In our earlier investigations, hexane extracts were used for the analysis of fatty acid of lipid components.) Many components of pentoses, hexoses and disaccharides were identified using 73 and 217 Da mass and the Wiley Online Library search. The aim of this paper is not to identify and find new components, but to compare sugar components of tested samples of flour of cereals bread wheat and spelt and pseudocereals (amarnath and buckwheat). Results were analysed using descriptive statistics (dendrograms and PCA). The results show that this method can be used for making a distinction among different types of flour.

Practical method for the confirmation of authentic flours of different types of cereals and pseudocereals

Gas chromatography with mass spectrometry was used to perform a qualitative analysis of the liposoluble flour extract of different types of cereals (bread wheat and spelt) and pseudocereals (amaranth and buckwheat). In addition to major fatty acids, the liposoluble extract also contained minor fatty acids with more than 20 carbon atoms, higher hydrocarbons and phytosterols. TMSH (trimethylsulfonium hydroxide, 0.2 mol/l in methanol) was used as a trans-esterification reagent. In a trans-esterification reaction, triglycerides esterified from acilglycerols to methyl-esters. SIM (selected ion monitoring) was applied to isolate fatty acid methyl esters on TIC (total ion current) chromatograms, using the 74 Da fragment ion, which originated from McLafferty rearrangement, and is typical for methyl-esters. GC-MS system was used for the trans-esterification of triglycerides to fatty acid methyl esters in the gas chromatographic injector. This eliminated laboratory preparation for fatty acid methyl esters. Cluster analysis was applied to compare the liposoluble flour extract from different types of cereals and pseudocereals. Statistical data showed the liposoluble extract analysis enabled determination of flour origin and, because the results were unambiguous, this approach could be used for quality control.

Rapid Method for Small Grain and Corn Flour Authentication Using GC/EI–MS and Multivariate Analysis

The aim of this study was the application of the gas chromatography–mass spectrometry system (GC/EI–MS) system and multivariate data analysis to investigate the possibility of chemical differentiation between small grain flour (wheat, barley, oat, triticale, rye) and corn flour samples. All cereal flour samples were first defatted with hexane, after which the extraction with ethanol was performed. Extracted simple sugars (monosaccharides, disaccharides, trisaccharides, and sugar alcohols) were analyzed in the form of their corresponding trimethylsilyl oximes. Peaks of simple sugar derivatives were selected in total ion current (TIC) chromatograms by monitoring exclusively the following characteristic abundant ions: 204, 217, and 361 m/z. The total surface areas under the selected peaks were subjected to multivariate analysis. Applying principal coordinate analysis and hierarchical cluster analysis to obtained data, samples of corn flour could be very clearly distinguished from all samples of small grain flour, which presented a weaker separation among each other. This method circumvents common analytical procedures by excluding simple sugar identifications, quantitative analysis, the use of analytical standards, and calibration curves. Results are applicable in the quality assurance of mixed flour on the market, considering the increased popularity of their consumption in human nutrition.

Unusual Cases of Suicide Among Health Care Workers

We describe three unusual cases of suicide committed by health care workers. The aim of this paper was to analyze and evaluate the evidence of general diagnostic elements of poisoning in these cases.

Dioxolane acetal ring expansion during a sugar triflate displacement. Synthesis and assignment of diastereoisomer configuration of novel 9-crown-3 ether derivatives

Abstract Treatment of 2,5:3,6-dianhydro-6-thio-4- O -trifluoromethanesulfonyl- l -talose ethylene acetal ( 5 ) with lithium benzoate in boiling DMF unexpectedly gave the 9-crown-3 ether derivatives 7 and 8 instead of the substitution product 6 . The mechanism of the process presumably involved neighbouring group participation of the dioxolane acetal function. 1 H NMR and molecular mechanics calculations (MM3) provided the assignment of stereoisomer configuration since the results of semi-empirical PM3 calculations on postulated oxonium-ion intermediates reasonably explained the high stereoselectivity of the process.