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Thermal lens spectrometry - still a technique on the horizon?
Mladen Franko, 2015

Abstract: In 1980’s thermal lens spectrometry (TLS) was still considered as a “spectrometric technique on the horizon” as one can also read from one of the textbooks on spectrochemical analysis of that time. Intensive development of thermal lens instrumentation and methods of chemical analysis and material characterisation has however resulted in substantial progress in this field, which is evident from important instrumental innovations and first commercial instruments (i.e. thermal lens microscopes -TLM) designed for lab-on-a-chip chemistry as well as from novel applications of TLS in various areas, where highly sensitive and rapid chemical analysis of complex samples is needed, including food safety and quality control, environmental analysis and biomedical diagnostics. This presentation is a review of most significant contributions and applications of thermal lens spectrometry, with emphasis on most recent achievements in instrumentation, which culminated into construction of novel optimized TLM instruments, capable of exploiting the tuneability of incoherent light sources and enabled novel applications particularly in micro-fluidics. Based on latest progress relying on bio-analytical assays and micro-fluidic flow injection with TLM detection we have also witnessed firs routine applications of TLS in analytical and diagnostic laboratories, which on wine side actually classifies TLS as a conventional and routine analytical tool, but at the same time opens new horizons for development and applications of this ultrasensitive and rapid spectrometric technique.
Found in: ključnih besedah
Summary of found: ...progress relying on bio-analytical assays and micro-fluidic flow injection with TLM detection we have also... ...from one of the textbooks on spectrochemical analysis of that time. Intensive development of thermal...
Keywords: Thermal lens spectrometry, applications, Liquid chromatography, flow injection analysis, bioanalytical methods
Published: 29.03.2016; Views: 2329; Downloads: 0
.pdf Fulltext (609,15 KB)

Optimised calibration procedure for bioanalytical determination of organophosphate pesticides in apple juices by immobilised AChE
Boris Pihlar, Klavdija Mežnar, Mladen Franko, Lea Pogačnik, 2003, original scientific article

Abstract: Optimised calibration procedure for bioanalytical determination of organophosphate pesticides in apple juices by immobilised AChE
Found in: ključnih besedah
Summary of found: ...pesticidi, sadni sokovi, analytical techniques, biosensors, FIA, flow injection analysis, pesticides, fruit juices, ...
Keywords: analitske metode, biosenzorji, pesticidi, sadni sokovi, analytical techniques, biosensors, FIA, flow injection analysis, pesticides, fruit juices
Published: 17.05.2016; Views: 1805; Downloads: 6
URL Fulltext (0,00 KB)

Franja Prosenc, 2017, doctoral dissertation

Abstract: Water security and quality are a global issue of concern, which have recently become alarming due to the growth of the human population, industrialisation and expanded agricultural activities. Biologically active compounds, such as pharmaceuticals and personal care products can have major adverse effects on aquatic organisms, and are therefore one of the biggest threats in water quality. Another major concern is the spread of waterborne pathogens, including multidrug resistant (MDR) bacteria, which can cause serious illnesses in humans. In order to maintain water abundance and quality, it is necessary that adequate wastewater treatment and analytical techniques allowing for sensitive and fast-response detection of water hazards are in place. Conventional (waste)water treatment technologies often fail to adequately remove all of the water hazards detailed above. Moreover, conventional analytical techniques currently used in water quality control are, although highly selective and sensitive, time-extensive, with throughput of merely 2 to 3 samples per hour, excluding the time for sample preparation. With respect to these drawbacks, research was proposed to explore new approaches for degradation of recalcitrant compounds, inactivation of microorganisms, and fast screening methods, which are listed in the second chapter of this dissertation as research objectives. In the third chapter, an extensive theoretical background on the hazards found in aquatic environment, namely pharmaceuticals and waterborne pathogens, is given. Pharmaceuticals enter the environment through several routes (disposal of unused medication via the toilet, pharmaceuticals passing through the human body unchanged/slightly transformed, animal excretions of pharmaceutically active compounds, insufficient wastewater treatment, etc.); therefore, traces of pharmaceuticals have repeatedly been reported in surface waters, groundwater, wastewater effluents, and even drinking water. Iodinated contrast agents (ICAs), as the compounds of interest in this project are further described. ICAs are eliminated from the human body practically unchanged; therefore a large proportion of them end up in municipal and hospital wastewater, where they can be present in concentrations of up to 2.4 g/L. Their ecotoxicity, degradation attempts, as well as detection monitoring in the environment are reviewed within the chapter. Additionally, waterborne pathogens, which account for 2.2 million deaths per year, are reviewed in this chapter, with emphasis on multidrug-resistant (MDR) bacteria. Although MDR infections are mostly prevalent in hospital environments, the presence of MDR bacteria in the environment is not a rarity. A high percentage of bacterial isolates in waters have been shown to be of an MDR phenotype. The theoretical background in analytical methods in water quality monitoring is also given in this chapter. Vanguard and rearguard techniques are explained, the first offering simple, cheap, and rapid sample screening, but sacrificing sensitivity and selectivity, whereas the second providing the highest quality information, excellent sensitivity and selectivity, but in expense of complicated and timely sample handling and high-cost instruments. By combining the two techniques the benefits of both can be exploited in a single system. The basic principles of thermal lens spectrometry (TLS) and its miniaturised version - the thermal lens microscopy (TLM) as fast screening methods providing high sensitivity are further explained, and their practical applications are reviewed. Furthermore, composite materials have recently been finding applications in water treatment technologies, as filter materials, adsorptives for pollutants, catalysts for degradation reactions, and disinfectants. The applications of three main types of composites: synthetic composites, biocomposites, and nanocomposites, are also reviewed within this chapter. The core of this dissertation is presented in the fourth and the fifth chapter, which examine two separate approaches for water treatment, as well as analytical methods for fast screening purposes. The fourth chapter is investigating options for degradation of iodinated X-ray agents (ICAs), namely diatrizoate, through biodegradation with extracellular enzymes of white rot fungus Dichomitus squalens, and chemical oxidation with manganese(III) acetate. Enzymatic degradation with laccase (Lac) and manganese peroxidase (MnP) at low enzymatic activities was unsuccessful, whereas at approximately 3-times higher activities the enzymes were capable of 60 % degradation in 12 days. Chemical oxidation of diatrizoate with manganese(III) acetate resulted in 85 % degradation in 12 days. Moreover, the suitability of microfluidic flow injection analysis coupled with thermal lens microscopy (μFIA-TLM) as a fast screening method for diatrizoate degradation was examined. The degradation was monitored through the release of iodide from the diatrizoate molecule. μFIA-TLM proved to be a preferable method over UV-Vis spectrophotometry, due to its higher sensitivity, sample throughput, and simple sample handling. Limit of detection (LOD) for μFIA-TLM method was estimated to be 0.14 µM in a 100 µm channel, which is 9 times lower than LOD obtained in UV-Vis measurements. In addition to μFIA-TLM and UV-VIS, high-pressure liquid chromatography (HPLC) was used to monitor the remaining parent compound in the reaction mix. In the fifth chapter, the second water treatment approach is described. This includes synthesis of biocomposite materials from cellulose (CEL) and keratin (KER), with metal (Ag0, AgCl, Au0) nanoparticles (NPs). Materials were characterised for presence, species, and size of NPs with X-ray diffraction (XRD) and with scanning electron microscopy (SEM). Nanoparticles were confirmed to be of expected species, with sizes as follows: 6.3 ± 0.5 nm for Au NPs, 12 ± 2 nm for Ag NPs, and 22 ± 1 nm for AgCl NPs. In order to evaluate antibacterial properties of the materials, contact tests with gram-negative (Escherichia coli and Pseudomonas aeruginosa) and gram-positive bacteria (Staphylococcus aureus, Methicillin-resistant S. aureus (MRSA), and Vancomycin-resistant Enterococcus faecalis (VRE)) were conducted. Direct-contact assay over 24 hours showed a dose and species-dependent antibacterial activity of [CEL:KER + Ag NPs] materials. The highest potency against the selected bacteria (up to 6-log of reduction) was observed for the material with 500 mg of Ag NPs. AgCl NPs appeared to be less potent than Ag NPs, whereas Au NPs exhibited antibacterial activity only against MRSA and VRE. In addition, antiviral properties of materials were investigated on selected bacteriophages (MS2, phiX174, and fr). However, biocomposite materials with 500 mg of Ag NPs and AgCl NPs, as well as, 240 mg of Au NPs did not exhibit any activity against selected bacteriophages. Biocompatibility with human fibroblasts was evaluated through a direct contact assay for 3 and 7 days of exposure. High concentrations of metal NPs turned out to be cytotoxic for human fibroblasts, whereas the amount of 69 mg of Ag NPs in [CEL:KER] was low enough not to affect the viability of the fibroblasts after 3 days of exposure. Composites with Ag NPs and AgCl NPs were also tested for leachability of NPs out of the materials. Both types of NPs were leaching out in two different forms, as silver ions, and as colloidal silver. Leaching of ionic silver from both materials stabilised after 3 days, whereas colloidal silver was still leaching out on the 7th day. The overall percentage of the total silver (ionic + colloidal) leached was only 0.04 % of silver incorporated in the material. In summary, this dissertation investigates alternative approaches for water treatment technologies, which could potentially serve as unit improvements of existing technologies, or as on-point pre-treatment technologies to facilitate further conventional water treatment techniques. It also demonstrates the suitability of μFIA-TLM for fast screening measurements in aquatic samples, offering high sample throughput, simple handling of the samples and superior sensitivity over the UV-Vis spectrophotometry.
Found in: ključnih besedah
Summary of found: ...12 days. Moreover, the suitability of microfluidic flow injection analysis coupled with thermal lens microscopy...
Keywords: Antibacterial biocomposites, nanomaterials, water treatment technologies, multidrug-resistant bacteria, iodinated contrast agents, thermal lens microscopy, flow-injection analysis, microfluidics
Published: 26.04.2017; Views: 2514; Downloads: 72
.pdf Fulltext (27,08 MB)

Speciation and Determination of Ionic and Trace-Level Colloidal Silver in Selected Personal Care Products by Thermal Lens Spectrometry
Dorota Korte, Ales Grahovac, Andrej Jerkic, Olga Vajdle, Jasmina Anojčić, Valeria Guzsvány, Bojan Budič, Mladen Franko, 2018, original scientific article

Found in: ključnih besedah
Summary of found: ...silver, Personal care products, Thermal lens spectrometric determination, Flow injection analysis...
Keywords: Silver nanoparticles, Colloidal silver, Personal care products, Thermal lens spectrometric determination, Flow injection analysis
Published: 26.02.2018; Views: 1200; Downloads: 0
.pdf Fulltext (1,25 MB)

Rapid and Sensitive Determination of ChE Activity in Blood Plasma
Andrej Jerkič, Tjaša Birsa, Mojca Žorž, Dorota Korte, Martina Bergant Marušič, Mladen Franko, 2018, published scientific conference contribution abstract

Found in: ključnih besedah
Summary of found: ... flow injection analysis,thermal lens spectrometric detection, acetylcholinesterase, ...
Keywords: flow injection analysis, thermal lens spectrometric detection, acetylcholinesterase, butyrylcholinesterase, enzyme activity
Published: 16.07.2018; Views: 1110; Downloads: 0
.pdf Fulltext (642,94 KB)

TLS-FIA System For Screening of Dissolved Iron in Ocean Water
Gaja Tomsič, Dorota Korte, Arne Bratkič, Mladen Franko, 2018, published scientific conference contribution abstract

Found in: ključnih besedah
Summary of found: ... flow injection analysis, iron concentration, ocean water, thermal...
Keywords: flow injection analysis, iron concentration, ocean water, thermal lens spectroscopy
Published: 16.07.2018; Views: 1154; Downloads: 0
.pdf Fulltext (679,78 KB)

Determination of Iron in Environmental Water Samples by FIA-TLS
Mladen Franko, Arne Bratkič, Dorota Korte, Hanna Budasheva, Leja Goljat, Gaja Tomšič, 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.
Found in: ključnih besedah
Summary of found: ...of thermal lens spectrometry (TLS) coupled to flow injection analysis (FIA) as a highly sensitive...
Keywords: Flow injection analysis, iron concentration, thermal lens spectroscopy
Published: 18.12.2019; Views: 295; Downloads: 18
.pdf Fulltext (690,39 KB)

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