An electrophoretic method (on-line coupled capillary isotachophoresis and capillary zone electrophoresis) with conductometric detection for the determination of free taurine in selected food and feed is described. Taurine is converted to isethionic acid by van Slyke method. Under optimized conditions (leading electrolyte: 5 mM HCl, 10 mM glycylglycine, and 0.05% 2-hydroxyethyl cellulose solution, pH 3.2; terminating electrolyte: 10 mM citric acid; background electrolyte: 50 mM acetic acid, 20 mM glycylglycine, and 0.1% 2-hydroxyethyl cellulose solution, pH 3.7), isethionic acid is separated from other sample components in anionic mode and detected using a conductimeter within 15 minutes. The performance method characteristics, such as linearity (25 - 1250 ng/mL), accuracy (99 ± 9%), repeatability (3.9%), reproducibility (4.3%), limits of detection (3 ng/mL) and quantification (10 ng/mL) were evaluated. By analysing 20 food and pet food samples the method was proved suitable for routine analysis. High sensitivity and selectivity, short analysis time and low costs are significant features of the presented method.
An electrophoretic method (on-line coupled capillary isotachophoresis with capillary zone electrophoresis) with conductometric detection (cITP-CZE-COND) for the determination of histamine in foodstuffs and feedstuffs is described. Under optimised conditions in cationic mode the histamine is well separated from other components of acidic sample extract and detected by conductimeter within 25 min. Method characteristics, i.e., linearity (22-222 ng/mL), accuracy (recovery 91 ± 9%), repeatability (1.5%), reproducibility (3.4%), and detection limit (4 ng/mL) were evaluated. On a representative series of 37 food and feed samples it has been shown that the cITP-CZE-COND gives comparable results as routine accredited HPLC method. Low laboriousness, high sensitivity, speed of analysis, and low running cost are important attributes of cITP-CZE-COND.
Na trhu se můžeme setkat s borůvkami různých druhů i odrůd rodu brusnice (Vaccinium), ale i s borůvkami jiných botanicky odlišných druhů rostlin. Cílem práce bylo seznámit čtenáře s různými druhy borůvek a zhodnotit jejich nutriční hodnotu. V rámci experimentální práce byl analyzován soubor 31 vzorků čtyř různých druhů borůvek se zaměřením na základní nutriční a technologické parametry (popel, rozpustná sušina, celkové cukry a kyseliny, celkové polyfenoly a antokyany).
Various kinds and varieties of blueberries of genus Vaccinium and botanically different kinds of blue-coloured berries are available jointly on the market. The aim of this study was to familiarize the reader with different kinds of blueberries and evaluate their nutritional value. The set of 31 samples of four different kinds of blue-coloured berries was analysed focusing on basic nutritional and technological parameters (ash, soluble solids, total sugars and acids, total polyphenols and anthocyanins).
Phytic acid (PA) and lower inositolphosphates (InsP(n) ) is the main storage form of phosphorus in grains or seeds. The content of PA and InsP(n) 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 InsP(n) 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 InsP(n) in barley varieties within an ongoing research project.
The aim of this work is detection of specific glucans extracted from barley grains of three varieties by the flow injection method of fluorescence analysis. The extract composition is monitored by HPLC of neutral sugars and FTIR spectrometry and improved by enzyme treatment (amylase and xylanase). The content of cereal ?-glucans in grains was determined using an enzyme set. The Aniline Blue dye and Fluorochrom (Biosupplies, Australia) were used as fluorescence agents. Both the agents show high sensitivity to ?(1›4) glycosidic bonds. Cereal ?-glucan and also ?-glucan did not form complexes. A statistically significant decrease in cereal ?-glucans was observed in infected grains. Purified extracts from infected grains showed more intense fluorescence than those from corresponding uninfected grains. This difference could be explained by the presence of mould ?-glucans. The flow injection fluorescence analysis is able to detect mouldinfected barley grains.
The aim of this work was to develop and validate electrophoretic methods for the determination of a new antiepileptic, lamotrigine (LAM). We tested the conditions for analysis of LAM in blood serum by two capillary isotachophoreses (ITP-ITP) and by capilary isotachophoresis – capillary zone electrophoresis (ITP-CZE). Best results were obtained using the ITP-CZE method with UV detection at 254 nm. The latter method offers a simple and rapid procedure for the determination of LAM in blood serum. A low sample volume is highly convenient especially for the determination in children. The analysis takes some 20 min. The linearity of the method was proved in the range 0?20 mg LAM/l. The limits of detection and quantification were 0.25 and 0.83 mg LAM/l, respectively. The variation coefficients were below 10 % at three concentration levels (1, 7 and 20 mg l????????????[na]1). The method was compared with HPLC using the Passing-Bablok regression analysis; no significant differences were found.
