51. The impact of Saccharomyces and non-Saccharomyces yeasts on wine colour: a laboratory study of vinylphenolic pyranoanthocyanin formation and anthocyanin cell wall adsorptionJelena Topić, Lorena Butinar, Alen Albreht, Irena Vovk, Dorota Korte, Branka Mozetič Vodopivec, 2020, original scientific article Keywords: Non-Saccharomyces yeast, Hydroxycinnamate decarboxylase activity, Sequential fermentation, Vinylphenolic pyranoanthocyanins, Anthocyanin adsorption Published in RUNG: 23.01.2020; Views: 3227; Downloads: 0 This document has many files! More... |
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54. Determination of Iron in Environmental Water Samples by FIA-TLSMiha Tomšič, Leja Goljat, Hanna Budasheva, Dorota Korte, Arne Bratkič, Mladen Franko, 2019, original scientific article Abstract: The determination of low concentration of iron in natural waters can be difficult due to the complexity of natural water, but primarily because it requires preconcentration of the sample with solvent extraction. In this work we report on results of thermal lens spectrometry (TLS) coupled to flow injection analysis (FIA) as a highly sensitive FIA-TLS method of iron detection. The concentration of iron redox species was determined using 1,10-phenanthroline (PHN), that forms stable complexes with Fe(II) ions which are characterized by an absorption maximum at 508 nm. The TLS system using a 633 nm probe laser and 530 nm pump laser beam was exploited for on-line detection in flow injection analysis, where a PHN solution was used as the carrier solution for FIA. The concentration of the complexing agent affects the quality of the TLS signal, and the optimal concentration was found at 1 mM PHN. The achieved limits of detection (LODs) for Fe(II) and total iron were 33 nM for Fe(II) and 21 nM for total iron concentration. The method was further validated by determining the linear concentration range, specificity in terms of analytical yield and by determining concentration of iron in a water sample from a local water stream. Keywords: Flow injection analysis, iron concentration, thermal lens spectroscopy Published in RUNG: 18.12.2019; Views: 3286; Downloads: 105 Full text (690,39 KB) |
55. A multi-thermal-lens approach to evaluation of multi-pass probe beam configuration in thermal lens spectrometryHumberto Cabrera, Leja Goljat, Dorota Korte, Ernesto Marin, Mladen Franko, original scientific article Abstract: In this work, a recently proposed thermal lens instrument based on multi-pass probe beam concept is investigated and described as a multi-thermal-lens equivalent system. A simulation of the photothermal lens signal formation in a multi-thermal-lens equivalent configuration of the system is performed and validated by comparing the experimental signals of single, dual and ten-pass configurations to theoretically calculated values. The theoretically predicted enhancement of the signal is 9 to 10-fold for a weak thermal lens when comparing the ten-pass configuration with the conventional single-pass thermal lens system. Experimentally achieved signal enhancement in the ten-pass system is 8.3 for pure ethanol sample and between 8 and 9 for solutions with different concentrations of the Fe(II) - 1,10-Phenanthroline complex. Additionally, a value of 9.1 was calculated as the ratio of the slopes of the calibration lines obtained using the ten-pass and single-pass configurations. The achieved limit of detection for determination of Fe(II), in the ten-pass configuration, was 0.4 µgL-1, with a relative standard deviation around 4.5%, which compares favorably with previously reported results for TLS determination of Fe(II) in thin samples using low excitation power. For the multi-pass configuration the linear range of measurement is reduced when compared to the single-pass configuration. This is explained by the theoretical analysis of the photothermal signal under multi-pass condition, which shows the important contribution of the nonlinear term in the theoretical expression for the photothermal signal. The ten-pass configuration, which is presented and validated experimentally for the first time, offers important signal enhancement needed in recently developed TLS instruments with tunable, low power excitation sources. Keywords: Thermal lens spectrometry, Photothermal detection, Trace determination, Chemical sensor Published in RUNG: 10.12.2019; Views: 3245; Downloads: 0 This document has many files! More... |
56. Quantitative detection of Microcystis aeruginosa in fresh water using single domain antibodies (VHHs)Gbenga Folorunsho Oginni, Sandra Oloketuyi, Elisa Mazzega, Mladen Franko, Hanna Budasheva, Dorota Korte, Ario De Marco, published scientific conference contribution abstract Keywords: thermal lens spectrometry, nanobodies, fluobodies, cyanobacteria Published in RUNG: 18.11.2019; Views: 3628; Downloads: 122 Full text (15,09 KB) |
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58. Developing DGT technique for determination of iron redox species by photothermal beam deflection spectrometryHanna Budasheva, Arne Bratkič, Chang Zhou, Dorota Korte, Yue Gao, Mladen Franko, Bruno Delille, 2019, published scientific conference contribution abstract Keywords: Diffusive Gradients in Thin Films, Beam Deflection Spectrometry, iron redox species Published in RUNG: 25.09.2019; Views: 3452; Downloads: 0 This document has many files! More... |
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