František Kvasnička

Determination of phenolic acids by capillary zone electrophoresis and HPLC

Selected phenolic acids are determined by capillary zone electrophoresis and HPLC, each using UV detection. The optimised CZE background electrolyte contained 50 mM acetic acid, 95 mM 6-aminocaproic acid, 0.1% polyacrylamide, 1% polyvinylpyrrolidone, and 10% methanol. Twelve phenolic acids (gallic, p-hydroxybenzoic, 3,4-dihydroxybenzoic, vanillic, syringic, o-coumaric, p-coumaric, caffeic, sinapic, ferulic, salicylic and chlorogenic) were separated within 10 minutes. Chromatographic separation of these phenolic acids was carried out on an Eclipse XBD C8 column using a mobile phase gradient (acetonitrile / methanol / water / 0.1% phosphoric acid); all were separated within 25 minutes. Electrophoretic and chromatographic determinations of ferulic and chlorogenic acids were compared on barley, malt, and potato samples. The methods’ characteristics were: linearity (1–20 mg ml and 0.2–4 mg ml−1), accuracy (recovery 94 ± 5% and 96 ± 4%), intra-assay repeatability (4.1% and 3.5%), and detection limit (0.2 and 0.02 mg ml−1).

Electrophoretic determination of calystegines A3 and B2 in potato

Potatoes, members of the Solanaceae plant family, contain calystegines, water-soluble nortropane alkaloids, which are biologically active as glycosidase inhibitors. The content of calystegines A(3) and B(2) in different varieties of potato and in various parts of the tubers (whole potato, peel, flesh, and sprouts) were analysed by new capillary zone electrophoresis and capillary isotachophoresis methods and by the routine GC method. The optimized background electrolyte for capillary zone electrophoretic analysis was mixture of 20 mM histidine, 20 mM N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid and 20% (v/v) methanol in demineralized water. Calystegines were detected by indirect UV detection at 210 nm. A clear separation of calystegines from other components of the methanolic sample extract was achieved within 4 min. The electrolytes for isotachophoretic analysis consisted of 5 mM NH(4)OH, 10 mM N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid, 0.1% hydroxyethylcellulose and 20% (v/v) methanol in demineralized water (leading) and 5 mM histidine+10 mM acetic acid+20% (v/v) methanol in demineralized water (terminating). Calystegines were separated within 20 min and detected by a conductimeter. Method characteristics of both zone electrophoresis and isotachophoresis, i.e., linearity (10-100 ng/microl and 1-10 ng/microl), accuracy (recovery 96+/-5% and 98+/-4%), intra-assay repeatability (4.2% and 3.5%), and detection limit (3 and 0.4 ng/microl) were evaluated. Simple sample preparation, sufficient sensitivity, speed of analysis, and low running cost are important attributes of the electrophoretic methods. The overall results of electrophoretic methods were comparable with GC.

Determination of phytic acid and inositolphosphates in barley

Phytic acid (PA) and lower inositolphosphates (InsPn) is the main storage form of phosphorus in grains or seeds. The content of PA and InsPn in different varieties of barley was analyzed by capillary isotachophoresis and online‐coupled capillary isotachophoresis with CZE. The electrolytes (in demineralized water) for the isotachophoretic analysis consisted of 10 mM HCl, 14 mM glycylglycine, and 0.1% 2‐hydroxyethylcellulose (leading) and 10 mM citric acid (terminating). The optimized electrolytes for the online coupling isotachophoresis with zone electrophoresis analysis were mixtures of 5 mM HCl, 7 mM glycylglycine, and 0.1% 2‐hydroxyethylcellulose (leading), 20 mM citric acid, 10 mM glycylglycine, and 0.1% 2‐hydroxyethylcellulose (background) and 10 mM citric acid (terminating). PA and all studied InsPn were separated within 25 min and detected by a conductivity detector. Simple sample preparation (acidic extraction), sufficient sensitivity, speed of analysis, and low running cost are important attributes of the electrophoretic methods. The method was used for the determination of PA and InsPn in barley varieties within an ongoing research project.

Variability in phytic acid content in barley grain.

KATEŘINA VACULOVÁ, MARTA BALOUNOVÁ, FRANTIŠEK KVASNIČKA, IRENA SEDLÁČKOVÁ, JAROSLAVA EHRENBERGEROVÁ, ELIŠKA VÁCLAVÍKOVÁ, MILAN POUCH 1 Agrotest fyto, s.r.o. / Agrotest Fyto, Ltd. Havlíčkova 2787, 767 01 Kroměříž 2 Vysoká škola chemicko-technologická v Praze / Institute of Chemical Technology in Prague, Technická 5, 166 28 Praha 6 Dejvice 3 Mendelova univerzita v Brně / Mendel University in Brno, Zemědělská 1, 613 00 Brno e-mail: vaculova.katerina@vukrom.cz

Erratum to: “Occurrence of 2-phenylphenol in food paper packages”

The original version of the article was published in Cent. Eur. J. Chem. 12(11) (2014) pp. 1162–1168. Unfortunately, the original version of this article contains some mistakes in the Tables 2 and 3. Corrected versions of the tables are presented below.