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31.
CHARACTERIZATION OF BIOCOMPOSITE MATERIALS BY PHOTOTHERMAL BEAM DEFLECTION SPECTROMETRY
Hanna Budasheva, Patricia Cazon Diaz, Dorota Korte, Mladen Franko, Chieu D TRAN, prispevek na konferenci brez natisa

Ključne besede: EAM DEFLECTION SPECTROMETRY, BIOCOMPOSITE MATERIALS, porosity
Objavljeno v RUNG: 02.12.2021; Ogledov: 1718; Prenosov: 0
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Towards a novel method for iron species determination in Antarctic sea ice
Hanna Budasheva, Arne Bratkič, Dorota Korte, Mladen Franko, 2021, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Sea-ice borne iron has been found to be an important factor controlling Southern Ocean phytoplankton growth [1]. Knowing the amount and chemical speciation of its labile fraction in sea ice would advance our understanding of the involved processes. Unfortunately, it is rather difficult to perform their measurement because of limited access to the Antarctic. Thus there is a strong need for the development of a quick, simple and reliable technique for determination of iron and its speciation in sea-ice that ensures also low enough limits of detection. Recently, diffusive gradients in thin films (DGT) have been widely used as passive samplers for collecting time-averaged data on the concentrations of transition metals in different media [2]. DGTs are further coupled to an analytical technique that in case of detecting metals in passive sampler films primarily requires their extraction [3], which may potentially lead to changes of the metal specification. In the present study, the beam deflection spectrometry (BDS) is coupled to DGT and used to determine the average concentration of iron in the sea ice samples collected at the Davis Station in the Antarctic. Such a combined technique has been already successfully applied for detecting labile iron species in freshwater sediments [4]. The obtained BDS data were validated by thermal lens spectrometry (TLS) and UV-Vis spectrophotometry (SPEC). The distribution of iron species over a given ice surface area using the DGT-BDS technique revealed total iron concentrations in the range of 0.6 – 5.3 μgL-1, whereas the Fe2+ content was found to be in the range of 0.1 – 1.5 μgL-1. The range taking into account all of the measurement points (5×4), the precision of a single measured point is 0.2 μgL-1. The calculated 24 h-average concentration of total Fe labile species in the ice by using BDS is 2.3 ± 0.5 μgL-1, which coincides with data obtained by SPEC (2.5 ± 0.4 μgL-1) and TLS (2.39 ± 0.02 μgL-1). Our results indicate that it is possible to develop a robust, contamination-resilient detection method for measuring the labile iron species concentration in the sea ice. In opposite to TLS and SPEC, BDS-DGT provides reliable information not only about the speciation of iron but also about their distribution on the ice surface.
Ključne besede: beam deflection spectrometry, diffusive gradients, thin films, iron species, photothermal techniques, Antarctic sea ice
Objavljeno v RUNG: 30.11.2021; Ogledov: 2156; Prenosov: 0
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Thermal lens spectrometric detection in microfluidic systems
Mladen Franko, 2020, objavljeni znanstveni prispevek na konferenci (vabljeno predavanje)

Ključne besede: thermal lens, spectrometric detection, microfluidic systems
Objavljeno v RUNG: 17.12.2020; Ogledov: 2866; Prenosov: 12
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39.
Implementation of high performance liquid chromatography coupled to thermal lens spectrometry (HPLC‑TLS) for quantification of pyranoanthocyanins during fermentation of Pinot Noir grapes
Jelena Topič Božič, Lorena Butinar, Natka Ćurko, Karin Kovačević Ganić, Branka Mozetič Vodopivec, Dorota Korte, Mladen Franko, 2020, izvirni znanstveni članek

Opis: In this work high performance liquid chromatography coupled to thermal lens spectrometry (HPLC-TLS) was applied for monitoring of vinylphenolic pyranoanthocyanins formation during the fermentation of Pinot Noir wines. Vinylphenolic pyranoanthocyanins are wine pigments, present in low concentrations, but very important for wine colour stability. Fermentation process was conducted with four different yeast strains, used as starters, either in sequential fermentation of non-Saccharomyces with S. cerevisiae yeast or as single fermentation with S. cerevisiae yeasts in order to test the applicability of developed method for monitoring of selected compounds in real wine fermentation experiments. The developed HPLC-TLS method showed higher sensitivity compared to HPLC coupled to diode array detection (DAD) technique for particular wine colour compounds. Obtained limits of detection (LODs), were 6- and 22-times lower in comparison to HPLC–DAD in gradient and isocratic elution mode, respectively, whereas limits of quantification (LOQs) 5 and 18-times lower. Lower LODs enabled earlier observation of vinylphenolic pyranoanthocyanins formation during fermentation (already at day 7) in the case of HPLC-TLS method in gradient mode, while by using HPLC–DAD in gradient elution mode the formation of vinylphenolic pyranoanthocyanins was noticed only after 12 days of fermentation.
Ključne besede: Thermal lens spectrometry (TLS), High performance liquid chromatography (HPLC), Pyranoanthocyanins, Wine, Yeasts
Objavljeno v RUNG: 18.06.2020; Ogledov: 3201; Prenosov: 0
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