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Jena, Germany

Karmowski J.,Friedrich - Schiller University of Jena | Enke K.,Friedrich - Schiller University of Jena | Killenberg M.,Analytik Jena AG | Bohm V.,Friedrich - Schiller University of Jena
LWT - Food Science and Technology | Year: 2015

Antioxidant capacity as sum parameter necessarily includes interactions between antioxidants. Thus, two compounds out of a-tocopherol, lycopene, b-carotene and lutein were mixed and measured by lipophilic photochemiluminescence (PCL) assay and a-TEAC assay. In the a-TEAC assay, all mixtures showed an antagonistic effect. The highest antagonistic effect was found for all mixtures of b-carotene and lutein. In contrast, in the PCL system antagonistic, synergistic and additive effects were detected. The mixture b-carotene and lutein 2:1 had the highest synergistic effects. The presence of functional hydroxyl groups and hydrogen bonding effects may have an influence on the interactions. In both assays used, we observed a concentration-dependent effect. The influences of glucose, fructose, saccharose and starch on the antioxidant capacity were determined by PCL and a-TEAC, too. All sugars can have an effect on the lipophilic antioxidant capacity depending on the extraction solvent. The sugar samples, extracted with n-hexane, did not show any antioxidant capacity in a-TEAC assay. In the PCL, the antioxidant potentials of sugars were dependent on the extraction solvent and reflected the dissolubility of sugars in methanol. The better the solubility the higher the antioxidant capacity. Additionally, sugars did not interact with antioxidants, with exception of the methanolic fructose extract. © 2015 Elsevier Ltd. Source

Qin Z.,University of Aberdeen | McNee D.,University of Aberdeen | Gleisner H.,Analytik Jena AG | Raab A.,University of Aberdeen | And 5 more authors.
Analytical Chemistry | Year: 2012

Figure Persented: Driven by increasing demand for the monitoring of industrial perfluorinated compounds (PFCs), the identification of novel fluorine containing compounds (FOCs) and the tracking of organofluorine drugs and their degradation products, there is a clear need for sensitive, fluorine-specific detection of unknown FOCs. Here we report the first ever direct fluorine-specific (speciation) method; capable of individually detecting untargeted FOCs in environmental and biological samples through the application of continuum source molecular absorption spectrometry (CS-MAS) using a commercial CS-AAS. Two model FOCs (2,4,6, trifluorobenzoic acid (TFBA) and 5-fluoroindol-5-carboxylic acid (FICA)) were used, achieving fluorine-specific detection across a range of 0.1 to 300 ng/mL fluorine, corresponding to a limit of detection of 4 pg F and 5.26 nM for both compounds. Both TFBA and FICA showed a similar response to CS-MAS detection, potentially enabling the quantification of fluorine content in novel FOCs without having molecular standards available. This paper also reports the use of reverse-phase high performance liquid chromatography (RP-HPLC) coupled off-line with CS-MAS for the identification of single organofluorines in a mixture of FOCs via fraction collection. The linear range of both FOCs was determined to be from 1 to 500 ng/mL. The limits of detection of those species were just above 1 ng/mL (100 pg) and can therefore compete with targeted analytical methods such as ESI-MS. Finally, as a proof of principle the analysis of a fluoride-containing groundwater sample from Ghana demonstrated that this method can be used in the detection of novel FOCs, with identification achieved through parallel ESI-MS. Coupled HPLC-CS-MAS/ESI-MS is the first analytical methodology capable of selectively detecting and identifying novel FOCs, making possible the quantification of all fluorine containing compounds in one sample. This is the necessary analytical requirement to perform fluoronomics. © 2012 American Chemical Society. Source

Bauerfeind J.,Friedrich - Schiller University of Jena | Hintze V.,Friedrich - Schiller University of Jena | Kschonsek J.,Friedrich - Schiller University of Jena | Killenberg M.,Analytik Jena AG | Bohm V.,Friedrich - Schiller University of Jena
Journal of Agricultural and Food Chemistry | Year: 2014

The purpose of this study was to compare the antioxidant activity of carotenoids to that of α-tocopherol by using a photochemiluminescence method (PCL). Comparisons to results obtained by using other established methods (α-TEAC, FRAP, DPPH, LPSC) were carried out. A relationship between the chemical structure of carotenoids and their antioxidant activity could be discussed. The number of conjugated double bonds and functional groups had a positive influence. Additionally, the lipophilic antioxidant capacities of selected tomato products were analyzed using PCL and α-TEAC. HPLC was used to identify and quantify contents of carotenoids, tocopherols, and tocotrienols. The raw material fresh tomatoes had the lowest antioxidant effect in both assays due to the lower carotenoid content. Tomato ketchup had the highest AOC in PCL, and tomato puree, in α-TEAC. The antioxidant capacities were mainly dependent on the water content of the samples. Furthermore, a concentration-dependent effect could be observed in both assays. © 2014 American Chemical Society. Source

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Gleisner H.,Analytik Jena AG | Welz B.,Federal University of Santa Catarina | Welz B.,Federal University of Bahia | Einax J.W.,Friedrich - Schiller University of Jena
Spectrochimica Acta - Part B Atomic Spectroscopy | Year: 2010

The determination of fluorine using the molecular absorption of gallium mono-fluoride (GaF) at the 211.248 nm rotational line has been optimized using a commercially available high-resolution continuum source atomic absorption spectrometer with a transversely heated graphite tube furnace. The electron excitation spectrum of GaF was generated by adding 500 μg Ga per injection into the graphite tube as molecule forming reagent. Best results were obtained by applying Zr as a permanent modifier and a mixed Pd/Zr modifier, thermally pretreated before each sample injection together with the Ga reagent at 1100 °C. The use of sodium acetate and Ru(III) nitrosyl nitrate as additional modifiers injected together with the sample further improved the performance. This way a maximum pyrolysis temperature of 550 °C could be used, and the optimum molecule forming temperature was 1550 °C. Several drinking water samples, a mineral water sample, and two certified reference materials were analyzed using the standard calibration technique; the absence of potential matrix effects was verified by measuring different dilutions and spiking with known fluorine mass. The results were in good agreement with the certified values and those measured by ion selective electrode; the recovery rate for the spiking experiments was between 97% and 106%. The results show that there was no matrix influence for that kind of samples containing relatively high concentrations of Ca, Mg and chloride, which are known to cause interference in GaF molecule absorption. The limit of detection and the characteristic mass of the method were 5.2 and 7.4 pg F, respectively, and were both about a factor of two better than recently published values. © 2010 Elsevier B.V. All rights reserved. Source

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