Marijana M. Ačanski

Evaluation of the predictive power of calculation procedure for molecular hydrophobicity of some estradiol derivates.

Several calculation procedures for log P values based on the fragmental and atomic contributions are compared with experimental reversed-phase liquid chromatography (RPLC) retention of estradiol derivates. The RPLC experiments were performed on HPTLC and HPLC commercially available stationary phases. Binary solvent mixtures of methanol-water and acetonitrile-water were used as mobile phases. The correlation between log P and various chromatographically obtained hydrophobicity parameters (R(M)0, log k(w) and phi0) are quantified. The R(M)0, i.e., log k(w) were obtained by linear extrapolation of retention to 0% organic modifier. Phi0 values were obtained from the slopes and intercepts of such linear relationship. The mutual relationship between phi(0,MeOH) and phi(0,ACN) values of the compounds were discussed. The obtained statistical results can be summarized in the following order of reliabilities for different log P calculation methods: Broto>ACD/logP>Crippen>Rekker>Viswanadhan.

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.

High-performance liquid chromatography of some estrogens on chemically bonded phases

SummaryThe chromatographic behaviour of 30 estradiol and estrone derivatives has been studied on diol, amino- and cyanopropyl silica gel stationary phases with non-aqueous mobile phases. The slopes of linear relationships between the logarithm of the retention factor and logarithm of the volume fractions of the polar components of the binary eluents have been calculated and are discussed in relation to the characteristics of the solute, eluent and stationary phase. An equation for testing the separation efficiency of stationary phases has been derived.

Reversed phase liquid chromatography of some benzimidazole derivatives

SummaryThe retention behaviour of a series of benzimidazole derivatives has been studied as a function of the water content of aqueous methanol and aqueous acetonitrile eluents. The relationship between the retention constant (log k) and the pH of the aqueous phase was linear, with slope values depending on the composition of the aqueous phase, the molecular structure of the compound, and the type of C-18 bonded stationary phase. The type of organic modifier significantly affected the shape of the relationship between log k and the volume fraction of organic modifier in the mobile phase.

Characterization of the liposoluble fraction of common wheat (Triticum aestivum) and spelt (T. aestivum ssp. spelta) flours using multivariate analysis.

BACKGROUND In the present paper, a special method for derivatization of liposoluble extract of common wheat and spelt flours was employed which enables simultaneous detection of fatty acid and non-saponifiable lipid fractions. RESULTS Gas chromatographic-mass spectrometric analytical data for both fractions were separately analyzed by multivariate statistical techniques to model classes of different common wheat and spelt cultivars. Cluster analysis was used, and the results obtained revealed that better discrimination of samples was achieved by analyzing the peak area after 16 min retention time (non-saponifiable lipids), rather than commonly used peak area between 12 and 16 min (fatty acid fraction), due to more distinctive positions of points in factor space, even though the distances between points for fatty acid fraction (12-16 min) were greater. Similar results were obtained by principal components analysis, where all wheat points almost coincided whereas spelt showed good discrimination. CONCLUSION Comparison of chromatogram areas for non-saponifiable lipid fraction between common and spelt wheat showed a statistically high difference and hence has a potential for use in authenticity control.

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.

Normal and reversed phase high performance liquid chromatography of some new 1, 2, 4-triazole derivatives

The retention behaviour and separation ability of normal and reversed phase HPLC with one non-polar and two polar mobile phases, have been studied by measuring the retention constants of a series of newly synthesized 1,2,4-triazole derivatives. The results are discussed in terms of the nature of the solute, eluent and stationary phase.

Authentication of Cereal Flours by Multivariate Analysis of GC–MS Data

In this work flour samples of various cereal species, a group of different cultivars of small grain species (wheat, Triticum spp.; barley, Hordeum vulgare; oat, Avena sativa; rye, Secale cereale; triticale, Triticosecale) and cultivars of corn species, Zea Mays, growing in the same period and in the same geographical area, were selected to establish differences between each other, using a new rapid method: a comparison of derivatized hexane extracts by GC–MS and multivariate analysis, using the characteristic fragmentation ion m/z 74, without performing qualitative and quantitative analysis of eluting components. Obtained results were compared with the results obtained using a common electron microscopy method. Flour samples made of every corn and oat cultivar showed complete differences compared to flour samples of each wheat, barley, rye and triticale cultivar investigated in this study. The GC–MS approach combined with multivariate analysis outperforms the standard electron microscopy method in a faster and easier way, and may be used to verify flour types in the market.