11. Preparation of porous [alpha]-Fe[sub]2O[sub]3 thin films for efficient photoelectrocatalytic degradation of basic blue 41 dyeManel Machreki, Takwa Chouki, Mitja Martelanc, Lorena Butinar, Branka Mozetič Vodopivec, Saim Emin, 2021, original scientific article Abstract: A novel method was developed for the preparation of porous hematite (α-Fe2O3) thin films. First, a solution containing iron precursor was spin-coated on fluorine-doped tin oxide substrate and later short heat-treated at 750 °C. The prepared α-Fe2O3 thin films were applied as dual-function catalyst in photoelectrochemical (PEC) water oxidation and textile dye degradation studies. For the first time, α-Fe2O3 thin films were used in efficient PEC degradation of a textile dye (Basic Blue 41 – B41) using in-situ generated reactive chlorine species. In comparison with photocatalytic and electrocatalytic approaches, the PEC technique allows faster degradation of B41 dye at an applied bias potential of 1.5 V versus reversible hydrogen electrode and under visible light illumination. In the presence of Cl− using the PEC approach the degradation of B41 reaches 99.8%. High-performance liquid chromatography coupled with UV–VIS system confirmed the degradation of B41 dye using PEC. Gas-chromatography coupled to mass spectrometry was used to study the by-products obtained during PEC degradation. Chemical oxygen demand analyses confirmed that the mineralization level of B41 is in the order of 68%. The α-Fe2O3 films developed in this study give a higher level of PEC degradation efficiency compared to other iron oxide-based systems.
Keywords: thin films, photoelectrocatalysis, kinetics, visible light, degradation, textile dye
Published in RUNG: 10.05.2021; Views: 2358; Downloads: 12
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12. NOVEL APPROACHES FOR THE DETERMINATION OF BIOGENIC AMINES IN FOOD SAMPLESMladen Franko, Mojca Žorž, Mitja Martelanc, Sara Budal, 2017, original scientific article Abstract: In this work, new analytical approaches for determination of biogenic amines in wines were developed.
For the first time, we studied the derivatization of BAs in wines with naphthalene- 2,3-dicarboxaldehyde (NDA) and with dabsyl chloride (DBS) and analysis of derivatized BAs by HPLC coupled to fluorescence (HPLC-NDA-FL) and thermal lens spectrometry (HPLC-DBS-TLS) detectors. The sensitivity of the two methods (LODs HPLC-NDA-FL in the range 27-73 μg/L; LODs HPLC-DBS-TLS in the range 3.4-11 μg/L) was higher than that of the official method for biogenic amines in wines, OIV-MA-AS315-18 (60-77 μg/L). For its best performances, the HPLC-DBS-TLS technique was applied to the analysis of putrescine, cadaverine, histamine and tyramine in two white wine samples. Additionally, exploiting the Berthelot reaction, the TLS fast screening of biogenic amines in wines, following the release of ammonia by transglutaminase, was also proposed. This approach allowed us to determine total biogenic amount content in concentrations below 0.1 mg/L, expressed as equivalents of histamine.
Keywords: biogenic amines, NDA, liquid chromatography, TLS, fluorescence, wine
Published in RUNG: 02.11.2017; Views: 4461; Downloads: 270
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13. Bilirubin is an Endogenous Antioxidant in Human Vascular Endothelial CellsLovro Žiberna, Mitja Martelanc, Mladen Franko, Sabina Passamonti, 2016, original scientific article Abstract: Bilirubin is a standard serum biomarker of liver function. Inexplicably, it is inversely correlated with
cardiovascular disease risk. Given the role of endothelial dysfunction in originating cardiovascular
diseases, direct analysis of bilirubin in the vascular endothelium would shed light on these relationships.
Hence, we used high-performance liquid chromatography coupled with thermal lens spectrometric
detection and diode array detection for the determination of endogenous cellular IXα-bilirubin. To
confirm the isomer IXα-bilirubin, we used ultra-performance liquid chromatography coupled with a
high-resolution mass spectrometer using an electrospray ionization source, as well as tandem mass
spectrometric detection. We measured bilirubin in both arterial and venous rat endothelium (0.9–1.5
pmol mg−1 protein). In the human endothelial Ea.hy926 cell line, we demonstrated that intracellular
bilirubin (3–5 pmol mg−1 protein) could be modulated by either extracellular bilirubin uptake, or by
up-regulation of heme oxygenase-1, a cellular enzyme related to endogenous bilirubin synthesis.
Moreover, we determined intracellular antioxidant activity by bilirubin, with EC50 = 11.4 ± 0.2 nM, in
the range of reported values of free serum bilirubin (8.5–13.1 nM). Biliverdin showed similar antioxidant
properties as bilirubin. We infer from these observations that intra-endothelial bilirubin oscillates, and
may thus be a dynamic factor of the endothelial function.
Keywords: Antioxidants, bilirubin, endothelial cells
Published in RUNG: 07.07.2016; Views: 5019; Downloads: 406
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14. Highly Sensitive Determination of Pyoverdine in Cloud Water by HPLC-Thermal Lens SpectrometryLeja Goljat, Mitja Martelanc, Virginie Vinatier, Anne-Marie Delort, Mladen Franko, 2016, published scientific conference contribution abstract Abstract: New method for pyoverdine and Fe(III)-pyoverdine detection was developed. Two isomers of pyoverdine and two isomers of Fe(III)-pyoverdine were separated isocraticaly on reversed-phase (RP)-C18 chromatograhic column and detected by DAD, FLD and TLS. HPLC-TLS method enables separation and determination of pyoverdine and Fe(III)-pyoverdine in a single run and excels in superior sensitivities when compared to conventional HPLC-DAD system.
Keywords: Pyoverdine, Fe(III)-pyoverdine, cloud water, high-performance liquid chromatography, thermal lens spectrometry
Published in RUNG: 04.07.2016; Views: 5611; Downloads: 0 |
15. Application of high-performance liquid chromatography combined with ultra-sensitive thermal lens spectrometric detection for simultaneous biliverdin and bilirubin assessment at trace levels in human serumMitja Martelanc, Lovro Žiberna, Sabina Passamonti, Mladen Franko, 2016, original scientific article Abstract: We present the applicability of a new ultra sensitive analytical method for the simultaneous determination of biliverdin and bilirubin in human serum. The method comprises isocratic reversed-phase(RP) C18 high-performance liquid chromatography (HPLC) and thermal lens spectrometric detection (TLS)based on excitation by a krypton laser emission line at 407 nm. This method enables the separation of IX-α biliverdin and IX-α bilirubin in 11 min. with limit of detection (LOD) and limit of quantitation (LOQ) for
biliverdin of 1.2 nM and 3 nM, and 1nM and 2.8 nM for bilirubin,respectively.In addition, a step-gradient elution was set up, by changing the mobile phase composition, in order to further enhance the sensitivity for bilirubin determination with LOD and LOQ of 0.5 nM and 1.5 nM, respectively. In parallel, an isocraticHPLC-DAD method was developed for benchmarking against HPLC-TLS methods. The LOD
and LOQ forbiliverdin were 6 nM and 18 nM, and 2.5 nM and 8nM for bilirubin,respectively. Additionally, both isocratic methods were applied for measuring biliverdin and free bilirubin in human serum samples (from 2 male and 2 female healthy donors). Combining isocratic HPLC method with TLS
detector was crucial for first ever biliverdin determination in serum together with simultaneous free bilirubin determination. We showed for the first time the concentration ratio of free bilirubin versus unbound biliverdin in human serum samples.
Keywords: Bilirubin, biliverdin, serum, HPLC, TLS
Published in RUNG: 29.03.2016; Views: 5581; Downloads: 0
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