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1.
Effective microorganisms technology applied to sewage sludge and tested in short exposure on Lepidium sativum
Tanja Buh, Leja Goljat, Darian Rampih, Petra Makorič, Sara Pignattelli, 2024, izvirni znanstveni članek

Opis: Sewage sludge has fertilizer properties and can supply a large amount of necessary nutrients to the crops, because it is full of organic matter, carbon, nitrogen and other nutrients, but on the other hand, it also contains a lot of toxic compounds, derived from its origin, such as heavy metals, antibiotics and microplastics. Effective microorganisms are a collection of naturally occurring beneficial microorganisms that are able to coexist and are commonly used in agriculture and gardening to improve plant performance and production. In this study, increasing concentrations of sewage sludge alone and added with effective microorganisms were evaluated in a short exposure on Lepidium sativum L. Parameters that were evaluated are: (i) percentage inhibition of germination, (ii) root length, (iii) biomass, (iv) soil pH, (v) total organic carbon and nitrogen both at soil and at root level. Results carried out from our experiment highlighted that effective microorganisms when coupled with sludge are able to restore biometric parameters by resetting seeds germinability inhibition and improving root elongation more than 50% when compared with plants added only with sludge, restoring the values almost of those to the control plants, as well as for soil pH values. Total organic carbon and total nitrogen are boosted at soil level almost at 50% when compared with the same concentrations added only with sludge, while at root level they appear decreased only in plants directly added with sludge treated with effective microorganisms
Ključne besede: sewage sludge, effective microorganism, total organic carbon, total nitrogen, germinability, short plants exposure, acute toxicity, biomass, pH
Objavljeno v RUNG: 12.04.2024; Ogledov: 1415; Prenosov: 3
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2.
Recent progress and applications of thermal lens spectrometry and photothermal beam deflection techniques in environmental sensing
Mladen Franko, Leja Goljat, Mingqiang Liu, Hanna Budasheva, Mojca Žorž, Dorota Korte, 2023, izvirni znanstveni članek

Opis: This paper presents recent development and applications of thermal lens microscopy (TLM) and beam deflection spectrometry (BDS) for the analysis of water samples and sea ice. Coupling of TLM detection to a microfluidic system for flow injection analysis (µFIA) enables the detection of microcystin-LR in waters with a four samples/min throughput (in triplicate injections) and provides an LOD of 0.08 µg/L which is 12-times lower than the MCL for microcystin-LR in water. µFIA-TLM was also applied for the determination of total Fe and Fe(II) in 3 µL samples of synthetic cloudwater. The LODs were found to be 100 nM for Fe(II) and 70 nM for total Fe. The application of µFIA-TLM for the determination of ammonium in water resulted in an LOD of 2.3 µM for injection of a 5 µL sample and TLM detection in a 100 µm deep microfluidic channel. For the determination of iron species in sea ice, the BDS was coupled to a diffusive gradient in the thin film technique (DGT). The 2D distribution of Fe(II) and total Fe on DGT gels provided by the BDS (LOD of 50 nM) reflected the distribution of Fe species in sea ice put in contact with DGT gels.
Ključne besede: thermal lens microscopy, beam deflection spectrometry, microfluidic system, microcystin-LR detection, iron species determination, ammonium detection
Objavljeno v RUNG: 03.01.2023; Ogledov: 2683; Prenosov: 37
.pdf Celotno besedilo (2,90 MB)
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3.
Determination of Iron in Environmental Water Samples by FIA-TLS
Miha Tomšič, Leja Goljat, Hanna Budasheva, Dorota Korte, Arne Bratkič, Mladen Franko, 2019, izvirni znanstveni članek

Opis: 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.
Ključne besede: Flow injection analysis, iron concentration, thermal lens spectroscopy
Objavljeno v RUNG: 18.12.2019; Ogledov: 4175; Prenosov: 111
.pdf Celotno besedilo (690,39 KB)

4.
A multi-thermal-lens approach to evaluation of multi-pass probe beam configuration in thermal lens spectrometry
Humberto Cabrera, Leja Goljat, Dorota Korte, Ernesto Marin, Mladen Franko, izvirni znanstveni članek

Opis: 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.
Ključne besede: Thermal lens spectrometry, Photothermal detection, Trace determination, Chemical sensor
Objavljeno v RUNG: 10.12.2019; Ogledov: 4200; Prenosov: 0
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5.
DETEKCIJA KOVINSKIH KOMPLEKSOV IN ORGANOKOVINSKIH SPOJIN V VZORCIH IZ OKOLJA S SPEKTROMETRIJO TERMIČNIH LEČ
Leja Goljat, 2019, doktorska disertacija

Opis: Environmental pollution is one of the greatest challenges that the world is facing today. Toxic compounds, such as pesticides, allergens, pharmaceuticals, toxins and heavy metals are widely present in the air, water and soil, and can affect the health of people and animals even in small quantities, as well as they may cause long- or short-term damage in plants [Hill, 1997]. Heavy metals (mercury, arsenic, cadmium…) are widely spread in the environment. They derive from a number of sources, including mining, industrial wastes and vehicle emissions [Tchounwou et al., 2012]. They are easily incorporated into biological molecules and exert their toxic effects by displacing essential metals of a lower binding power in biologically active molecules or by acting as noncompetitive inhibitors of enzymes, affecting neurological, reproductive, renal and hematological systems [Sunil D’Souza et al., 2003; Heavy-Metal Pollution, 2018]. Metals form countless compounds (e.g. metal complexes and organometallic compounds) which are essential for living organisms (vitamin B12, hemoglobin, chlorophyll) and/or have a wide range of applications in industry and other areas, including analytical chemistry. Because of the potential risk which toxic metals represent to the living organisms and also because of the importance of some essential metals, different analytical techniques and detection methods have been developed for studies of their occurrence, fate and concentration in the environment and in organisms. However, providing a required sensitivity for determination and speciation of different metals and their compounds, especially in small- volume samples is still a challenge. Therefore, general objectives of this dissertation were development of novel analytical methods for sensitive, reliable and fast determination of metal species, based on highly sensitive optothermal technique thermal lens spectrometry (TLS), which can be used as detection tool following colorimetric reaction of a selected metal ion or for direct detection of colored organometallic compounds. This dissertation is composed of the following chapters: introduction, research goals, theoretical background, results and discussion, conclusion and references. The core of this dissertation is presented in the fifth chapter (results and discussion), which is divided into three parts. They separately cover development of methods for determination of iron redox species, pyoverdine and Fe-pyoverdine complexes and mercury. Pyoverdine is a siderophore, excreted by a certain bacteria in order to scavenge iron in the environment and is closely related to the chemistry of iron in such biological systems. Therefore, the first two parts are closely related. Procedures for batch mode thermal lens microscopy (TLM), flow-injection thermal lens sprectrometry (FIA-TLS) and µFIA-TLM (flow injection and TLS detection in microspace) were developed for Fe(II) and Fe(III) determination, based on colorimetric reaction of Fe(II) with 1,10-Phenanthroline. All these procedures were focused on cloudwater examination with a tendency to minimize sample consumption but at the same time preserve low limits of detection (LOD) and limits of quantification (LOQ). TLM measurements with highly collimated probe beam were performed in a 100 μm optical path length cell (40 µL volume), which resulted in a considerably smaller sample volume requirement (500 µL in total) and consumption, as compared to UV-Vis spectrophotometry, which required at least 25 mL of sample due to large volume (almost 30 mL) of the 10 cm optical path-length sample cell. LODs for mode-mismatched TLM were 0.16 and 0.14 µM for Fe(II) and Fe(total) (sum of Fe(II) and Fe(III) concentrations), respectively, while LODs for UV-Vis spectrophotometry were 0.01 µM for both Fe(II) and Fe(total). By using the mode mismatched TLM we were able to detect concentrations corresponding to absorbances as low as 1.5 × 10-5, while the lowest absorbance detectable on the UV-Vis spectrophotometer corresponded to 1.1 × 10-3, despite the use of the 10 cm optical path-length cell. Another important step in the development of new methods for Fe(II) and Fe(III) determination was the use of TLS detection in FIA (FIA-TLS). By injecting 50 µL of the sample into the FIA-TLS system, cca. 10 times lower LODs were achieved (1 × 10-3 µM for Fe(II) and 8 × 10-4 µM for Fe(total)), as compared to the UV- Vis spectrophotometry. Nevertheless, the development of μFIA-TLM method, with on-line colorimetric reaction for Fe(II) and Fe(III) determination is considered as the most important achievement of this study. The results show that despite 100 times shorter optical path length and low sample consumption (3 µL of each sample/injection) compared to UV-Vis spectrophotometry, LODs for µFIA-TLM were 0.10 and 0.07 μM for Fe(II) and Fe(total) respectively, which is sufficiently for cloudwater analysis, since concentrations, lower than 0.1 μM are not expected [Parazols et al., 2006; Deguillaume et al., 2014]. Linear range for Fe(II) and Fe(III) determination by μFIA-TLM was between 0.1 and 70 µM. To test the accuracy of this method, artificial cloudwater was prepared, spiked with different amounts of Fe(II) and Fe(III) and analyzed for iron content by µFIA-TLM and UV-Vis spectrophotometry. Good agreement was observed between the two methods. To ascertain the ruggedness of the method 7 (or more) replicate determinations at two different concentrations for both, Fe(II) and Fe(total) in artificial cloudwater were carried out on day 1 (replicates were measured instantly after fortification), day 2 and day 5. A student’s t-test (p=0.05) was applied to compare 3 sets of obtained data (day 1, day 2 and day 5) and showed that sets are not significantly different from each other. Considering very low sample volume requirement of µFIA-TLM, this should be the method of choice for determination of Fe(II) and Fe(III) in investigations of processes in cloudwater, where multiparameter analysis is desired (determination of other ions, ligands, microbial counts, etc.). When larger sample volumes are available, FIA-TLS can be used for accurate determination of iron species at lowest concentration levels. High performance liquid chromatography (HPLC) was applied for separation and detection of pyoverdine (PVD), produced by Pseudomonas fluorescens 36b5, a bacterial strain isolated from the aqueous phase of clouds at the Puy de Dôme station (1465 m, France). Reversed-phase (RP) chromatography (RP-18 chromatographic column Hypersil gold), hydrophilic interaction liquid chromatography (HILIC) (ZIC®-Hilic column) and three different detection systems (diode-array (DAD), spectrofluorimetry (FLD) and TLS) were tested for their performance in separation and determination of pyoverdines and corresponding complexes of pyoverdine with iron (Fe(III)-PVDs). PVDs and Fe(III)-PVD complexes could not be separated and quantified by applying HILIC technique, therefore it was concluded, that HILIC is not suitable for HPLC-DAD and also not for HPLC-TLS, since the method should offer a simultaneous sensitive detection of free PVDs as well as Fe(III)-PVD complexes in a single chromatographic run. Since pyoverdine standards were available only as a mixture of several different forms of PVDs, whereby the exact composition was unknown, the quantification of each of the four major specie (two fluorescent PVDs and two nonfluorescent Fe(III)-PVDs) in the standard, which was obtained from Université Clermont Auvergne, Institut de Chimie de Clermont-Ferrand, was performed. When applying Hypersil gold column, a linear correlation between fluorescence intensity and absorbance of each component was observed in a concentration range 3–24 µg/mL, whereby LODs were estimated to be 0.03–0.04 µg/mL for each of the major PVD species (HPLC-DAD). Even though HPLC-FLD method provided cca. 100 times lower LODs, it is not the method of choice for determination of PVD species in cloudwater, because it does not allow detection of PVD complexes with Fe(III). When comparing HPLC-TLS and HPLC-DAD, LODs were 5 to 8 times lower in case of HPLC-TLS, which was a significant improvement. Furthermore, recoveries (89–111 %) at two concentration levels of four PVD species in two independent samples, showed good reliability of the method. Almost all mercury in uncontaminated drinking-water is thought to be in the form of Hg2+ [WHO, 2010]. Therefore, the method for Hg2+determination based on colorimetric reaction with triamterene, described originally by Al-Kady and Abdelmonem was further investigated in this study, as well as the possibilities of application of this reaction for Hg2+ determination by TLS. The stoichiometry of the complex formation was determined by the method of continuous variations and saturation experiment, suggesting formation of the complex with the formula Hg2-triamterene. The obtained value of the molar absorption coefficient was 9988 Lmol-1cm-1 at 403 nm, which significantly contradicts the existing data in literature, which reports the molar absorption coefficient of 5.32 × 104 Lmol-1cm-1 [Al-Kady and Abdelmonem, 2013]. Even though the spectrophotometric results were not encouraging for triamterene as colorimetric reagent for Hg2+ determination, it was further investigated for its performance in TLS system. Fe(II)-1,10-phenanthroline (ferroin) was used for comparison, because it was well studied for TLS applications previously. The results showed that Hg2-triamterene in solutions was degraded when it was exposed to the light of the excitation beam. Due to the lower molar absorptivity than reported in literature, fotodegradation and unfavorable complex stoichiometry, triamterene was not confirmed as a suitable colorimetric reagent for highly sensitive Hg2+ determination by TLS. In summary, this dissertation investigates alternative approaches for analysis of metal complexes and organometallic compounds in small-volume environmental water samples. Methods, which were developed in this research, could potentially serve as improvements of existing technologies, to facilitate analysis of such samples, by offering simple handling of samples and superior sensitivity over the UV-Vis spectrophotometry.
Ključne besede: thermal lens spectrometry, thermal lens microscopy, high performance liquid chromatography, microfluidics, metal complexes, organometallic compounds, iron, pyoverdine, mercury
Objavljeno v RUNG: 05.09.2019; Ogledov: 5710; Prenosov: 167
.pdf Celotno besedilo (3,65 MB)

6.
Novel methods and applications of photothermal techniques for speciation studies in environmental samples
Leja Goljat, Hanna Budasheva, Virginie Vinatier, Anne-Marie Delort, Dorota Korte, Mladen Franko, 2019, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: photothermal techniques, Fe determination
Objavljeno v RUNG: 16.07.2019; Ogledov: 4453; Prenosov: 0
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7.
DETERMINATION OF Fe2+ IN LIQUID SAMPLES BY THE USE OF AMPLIEFIED THERMAL LENS SPECTROMETRY
Humberto Cabrera, Dorota Korte, Leja Goljat, Mladen Franko, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: AMPLIEFIED THERMAL LENS SPECTROMETRY, Fe2+
Objavljeno v RUNG: 30.08.2017; Ogledov: 5240; Prenosov: 0
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8.
Investigation and determination of metal complexes and organometallic compounds by thermal-lens spectrometry
Leja Goljat, Mikhail A. Proskurnin, Ivan V. Mikheev, Mladen Franko, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: thermal-lens sprectrometry, thermal-lens microscopy, HPLC, metal complexes, organometallic compounds
Objavljeno v RUNG: 30.08.2017; Ogledov: 5396; Prenosov: 0
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9.
Comparison of Colorimetric Reagents and Their Applicability in Thermal Lens Spectrometry
Leja Goljat, Mikhail A. Proskurnin, Mladen Franko, 2017, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: thermal lens spectrometry, colorimetric reagents, mercury
Objavljeno v RUNG: 30.08.2017; Ogledov: 5126; Prenosov: 0
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10.
Highly Sensitive Determination of Pyoverdine in Cloud Water by HPLC-Thermal Lens Spectrometry
Leja Goljat, Mitja Martelanc, Virginie Vinatier, Anne-Marie Delort, Mladen Franko, 2016, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: 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.
Ključne besede: Pyoverdine, Fe(III)-pyoverdine, cloud water, high-performance liquid chromatography, thermal lens spectrometry
Objavljeno v RUNG: 04.07.2016; Ogledov: 6537; Prenosov: 0

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