Search

This work focusses on the analysis of anthocyanins present in wild Czech elderberries, using spectrophotometric methods and liquid chromatography. Spectrophotometric methods were used to determine antioxidant capacity, total phenolic content, and total anthocyanin content. Further, four major elderberry anthocyanins were determined using reversed-phase high-performance liquid chromatography with isocratic elution of 30% aqueous methanol with 5% of formic acid. All optimised methods were applied to the analysis of extracts prepared from frozen and dried elderberry fruit samples, and the results were evaluated using principal component analysis which clearly divided the samples into individual groups according to the sample pretreatment (frozen and dried samples). The frozen samples reached higher values of antioxidant capacity and total phenolic and anthocyanin contents compared to the dried samples, probably due to the degradation of anthocyanins during the drying process. [ABSTRACT FROM AUTHOR]

The nasturtium (Tropaeolum majus L.) contains many biologically active compounds with very promising effects on human health. Our attention was paid to glucotropaeolin and phenolic compounds that were simultaneously determined in different parts of nasturtium using rapid reversed-phase high performance liquid chromatography coupled to tandem mass spectrometry. Mainly isomers of hydroxycinnamic acid and derivatives of quinic acid, kaempferol, and quercetin were present. Moreover, many of them were identified for the first time. Their representation varied significantly depending on the part of nasturtium (flower, stem, seed, and leaf). Although the highest total concentration of the target compounds was found in leaves, all monitored compounds were present in flowers at concentrations higher than their limit of quantification. Furthermore, the effect of sample pre-treatment (drying and freezing) on their content was investigated. Surprisingly, frozen samples showed a considerable reduction in glucotropaeolin content. Finally, antioxidant capacity, total phenolic content, and total anthocyanin content were determined using spectrophotometric techniques and the results were compared to chromatographic data. [ABSTRACT FROM AUTHOR]

Coffee is a very popular beverage worldwide. However, its composition and characteristics are affected by a number of factors, such as geographical and botanical origin, harvesting and roasting conditions, and brewing method used. As coffee consumption rises, the demands on its high quality and authenticity naturally grows as well. Unfortunately, at the same time, various tricks of coffee adulteration occur more frequently, with the intention of quick economic profit. Many analytical methods have already been developed to verify the coffee authenticity, in which the high-performance liquid chromatography (HPLC) plays a crucial role, especially thanks to its high selectivity and sensitivity. Thus, this review summarizes the results of targeted and non-targeted HPLC analysis of coffee-based products over the last 10 years as an effective tool for determining coffee composition, which can help to reveal potential forgeries and non-compliance with good manufacturing practice, and subsequently protects consumers from buying overpriced low-quality product. The advantages and drawbacks of the targeted analysis are specified and contrasted with those of the non-targeted HPLC fingerprints, which simply consider the chemical profile of the sample, regardless of the determination of individual compounds present. [ABSTRACT FROM AUTHOR]

The content of 40 phenolic compounds was determined in 68 samples of extra virgin olive oils (EVOOs) coming from 9 Italian regions using high-performance liquid chromatography coupled to diode array detector and mass spectrometry. Oleuropein isomers (M = 540 g/mol) and derivatives (M = 378 g/mol) together with ligstroside aglycone isomers (M = 362 g/mol) and derivatives (M = 394 g/mol) were the major EVOOs compounds (median of 44–228 mg/kg). On the other hand, verbascoside isomers (M = 624 g/mol) and apigenin (M = 270 g/mol) were the minor compounds (median < 2 mg/kg). Different techniques of multivariate data analysis were applied to find important parameters for discrimination of EVOOs. Principal component analysis and factor analysis distributed the samples into two groups according to the total amount of phenols and quantity of elenolic acid giving information about ripeness of olives. Linear discriminant analysis successfully classified the samples according to their geographical origin into three groups (Northern Italy, Southern Italy, and Sicily). [ABSTRACT FROM AUTHOR]

Highlights: [•] New phase II metabolites were found during biotransformation of nabumetone in minipigs. [•] The metabolites were identified by coupling HPLC/ESI-MS/MS. [•] Phase I metabolites are subsequently conjugated with glucuronide acid and glycine. [•] Metabolites were found in small intestine content, they were absent in minipig urine. [ABSTRACT FROM AUTHOR]

The monitoring of phenolic compounds in mead is a useful tool for the evaluation of its quality and potential adulteration because the profile and content of phenolic compounds strongly depend on the amount and type of honey used for mead production and on the technological process. Therefore, the aim of this study was the optimization of rapid reversed-phase high performance liquid chromatography coupled to tandem mass spectrometry for the determination of 23 phenolic compounds in 22 mead samples. The isolation of monitored phenolic compounds was performed using liquid-liquid extraction with a mixture of diethyl ether and ethyl acetate. 3,4-dihydroxybenzoic, 4-hydroxybenzoic, caffeic, p -coumaric, salicylic, chlorogenic, gentisic, gallic and ferulic acids, together with apigenin, quercetin and 3,4-dihydroxybenzaldehyde were the most frequently occurred phenolic compounds in mead extracts. The instrumental limits of detection and quantification were for all compounds below 20 μg/L and 65 μg/L, respectively. Among the samples studied, four meads contained a low total amount of phenolic compounds (below 10 mg/L), and two of them did not even exceed 2 mg/L. Moreover, a very high concentration of vanillin as a flavouring was observed in one of those samples. • Rapid HPLC/MS/MS separation of phenolic compounds present in meads was optimized. • Phenolic profile and content strongly depend on the origin and quality of honey. • Phenolic content can help to assess the quality of mead. • Meads of poor quality were found among the analysed samples. [ABSTRACT FROM AUTHOR]

Abstract: Chromatographic behavior of block (co)oligomers of oxyethylene (EO) and oxypropylene (PO) surfactants in reversed-phase HPLC (RP-HPLC) was investigated. The retention of EO/PO block (co)oligomers depends on the distribution of the individual monomer repeat units, but the sequence of the individual blocks also plays a (less significant) role. The enthalpic and entropic contributions of the EO and PO repeat units to the retention were determined from the data measured at changing temperature. In RP-HPLC, the effect of the repeat PO units on separation is higher than the influence of the repeat EO units. In addition to the enthalpic contributions, the retention is significantly influenced by the entropy (possibly by the change of conformation and solvation of adsorbed molecules); dual molar mass distribution according to the number of EO and PO units complicates correct assignment of the chromatographic peaks to the individual (co)oligomers in complex samples based only on the chromatographic retention data. In spite of imperfect chromatographic separation, HPLC coupled with positive ion mode atmospheric pressure chemical ionization mass spectrometry allow identifying unambiguously the dual monomer distribution in the samples of EO–PO block (co)oligomers. [Copyright &y& Elsevier]

Abstract: Hops contain a wide range of polyphenolic compounds with antioxidant properties divided in various chemical classes. These compounds are detected in hop extracts and also in beer as its main product. Based on the careful optimization of column type, column packing, mobile phase composition and gradient steepness, two high-performance liquid chromatography–mass spectrometry (HPLC/MS) methods have been developed. The first method using Purospher Star RP-8e column and the gradient of aqueous acetonitrile containing 0.3% formic acid is optimized for the separation of low polar polyphenolic compounds, while the second one with Zorbax SB-CN column is used for more polar hops and beer components. In this work, more compounds are detected in comparison to previous reports. In total, 49 low polar and 37 polar compounds are detected in studied samples and their molecular weights are determined based on atmospheric pressure chemical ionization (APCI) mass spectra. Some compounds are identified based on the interpretation of their full scan and tandem APCI mass spectra, retention behavior and UV spectra, while the full structure elucidation of other species still requires further research. The quantitation of xanthohumol related prenylflavonoids and bitter acids is done with two detection techniques (APCI-MS and UV detection) providing comparable results. Both compound classes (i.e., prenylflavonoids and bitter acids) are separated and quantitated in a single HPLC run, where numerous other polyphenolics are detected as well. [Copyright &y& Elsevier]

• Fast and easy derivatization procedure of amino acids by PITC agent was developed. • Rapid separation of PITC derivates by HPLC with UV/VIS detection was optimized. • The method was successfully applied to samples of Czech meads. • Obtained results were compared with Harmonized spectrophotometric method. • The promising results pave the way for new related projects. Amino acids (AAs) are minor compounds occurring in meads contributing to their final organoleptic properties. Determination of AAs profile and content can help to assess the mead authenticity, adulteration and thus its quality. This work deals with the optimization of rapid analysis of 21 AAs present in mead using reversed-phase high performance liquid chromatography with spectrophotometric detection after simple derivatization procedure with phenyl isothiocyanate agent without any sample pre-treatment. Optimized derivatization and separation conditions have been successfully applied to the quantification of AAs present in five Czech meads using the multiple point standard addition method. The total amino acid content was in the range of 134−828 mg/L. The content of proline was confirmed by Harmonised spectrophotometric method. Both chromatographic and spectrophotometric methods provided overlapping results in the range of 30−266 mg/L. [ABSTRACT FROM AUTHOR]

A completely new voltammetric method has been developed for quantitative determination of food additive Taurine (Tau) in energy drinks. This electroanalytical method is based on voltammetric oxidation of o -phthalaldehyde-ethanthiol derivative of Tau at glassy carbon electrode in 95% methanol containing 0.1 mol L−1 lithium perchlorate. Working conditions necessary for quantitative Tau derivatization reaction and electrochemical detection using square wave voltammetry were optimized. Linear range from 1.0 × 10−5 to 1.0 × 10−4 mol L−1 characterized by coefficient of determination 0.9998, limits of quantification 6.8 × 10−6 mol L−1 and detection 2.1 × 10−6 mol L−1 were obtained at pulse amplitude 50 mV and frequency 80 Hz. Analytical method of calibration curve was used for evaluation of Tau content in several commercially available energy drinks. The procedure was validated using standard reference high performance liquid chromatography (HPLC) method. Both methods showed nearly identical Tau content, around 0.35% (w/w). Besides its reliability to the Tau determination, that is totally comparable to reference method used, present voltammetric approach is more advantageous on the economic and simplicity basis. Finally, developed voltammetric method could find employment in food quality control. Image 1 • The first scientific work focusing on reliable voltammetric determination of taurine. • Electroanalytical method based on anodic oxidation of isoindole derivative. • Fully comparable with the standard reference chromatographic method. • Suitable method for analysis of foodstuffs containing dominantly one amino acid. [ABSTRACT FROM AUTHOR]

This work deals with the rapid simultaneous determination of caffeine and the three most abundant chlorogenic acid isomers (3-, 4-, and 5-O-caffeoylquinic acids) present in 64 samples of regular (un)roasted and decaffeinated (un)roasted coffee beans using reversed-phase high-performance liquid chromatography with spectrophotometric detection. In the developed method, the target analytes were separated in just 6 min with a resolution higher than 1.2. Afterwards, factor analysis and principal component analysis were employed to reveal the relationships between the samples and the content of monitored compounds. The samples were successfully divided into three discrete groups (decaffeinated, roasted, and unprocessed) by these methods. Finally, the impact of sample roasting and decaffeination on the content of chlorogenic acid isomers was investigated. The decrease in 5-O-caffeoylquinic acid concentration during the decaffeination process was found not as significant as during the roasting process. Regarding caffeine isolation, dichloromethane was the best extraction solvent because it did not cause significant losses of chlorogenic acid isomers or changes in the coffee beans colour and its extraction efficiency reached 85%. [Display omitted] • Rapid simultaneous separation of chlorogenic acid isomers and caffeine using isocratic HPLC. • 64 regular and decaffeinated (un)roasted coffee samples were analysed. • Multivariate statistical methods were used for their classification. • Various solvents were tested for decaffeination of green coffee beans. [ABSTRACT FROM AUTHOR]

Mycotoxins have been widely studied by many research groups but further multidisciplinary research is needed to better understand and clarify many issues. This study describes the use of high-performance liquid chromatography coupled with ion trap mass spectrometry (HPLC-MS) to measure T-2 toxin and its metabolites, such as HT-2 toxin, neosolaniol (NEO) and diacetoxyscirpenol (DAS), as well as masked glucosylated mycotoxins in Fusarium -infected Czech spring barley. In total, 152 spring barley samples from the 2018 harvest were analyzed by the ELISA screening method for the presence of T-2 toxin. The most contaminated samples (15), which exceeded the recommended maximum level set by the EU for the sum of T-2 and HT-2 toxin in unprocessed cereals (200 μg/kg), were analyzed by HPLC-MS/MS and microbiological testing. Isolated fungi were evaluated microscopically and identified by polymerase chain reaction (PCR) assays. The prevalence of Fusarium species in spring barley across the Czech Republic in 2018 showed a predominance of F. poae (12 barley samples) and F. tricinctum (9 barley samples). Other strains (F. sporotrichioides and F. langsethiae) were present at a lower frequency, in 1 and 2 samples, respectively. The average concentration of T-2 plus HT-2 toxin was 107.7 μg/kg, while NEO and DAS were found in a few samples at values close to their limit of quantification. HT-2 glucoside was identified in all samples. • In total 152 barley samples were analyzed by ELISA for the presence of T2 toxin. • Fifteen of them exceeded the recommended maximum level set by the EU for the sum of T-2 and HT-2 toxin. • T-2 toxin and its metabolites including masked forms were identified and quantified by HPLC-MS/MS. • Cross-reactivity and overestimation of ELISA results compared to HPLC-MS/MS was confirmed. • In the most contaminated samples Fusarium tricinctum and Fusarium poae were predominant. [ABSTRACT FROM AUTHOR]