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61.
Experimental sessions: Thermal lens microscopy
Dorota Korte, Muhammad Sulaiman Yousafzai, prispevek na konferenci brez natisa

Ključne besede: Thermal lens microscopy, photothermal effect
Objavljeno v RUNG: 14.03.2017; Ogledov: 5398; Prenosov: 0
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62.
Thermal Lens Spectrometry and Microscopy Analytical Chemist’s Approach
Mladen Franko, vabljeno predavanje na konferenci brez natisa

Opis: This lecture introduces the basic concepts and recent progres in theory, instrumentation and applications of thermal lens spectrometry, thermal lens microscopy and their utilization for highly sensitive, and high throughput detection in liquid chromatography, flow injectionanalysis in microfluidic systems.
Ključne besede: Thermal lens spectrometry, TLS microscopy, theory, applications
Objavljeno v RUNG: 01.03.2017; Ogledov: 5251; Prenosov: 1
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63.
Determination of Trace Cr(VI) with Diphenylcarbazide by μFIA–Thermal Lens Microscopy
Tatyana Gor’kova, Michail Proskurnina, Mingqiang Liu, Mladen Franko, 2016, izvirni znanstveni članek

Opis: The optimum reaction parameters for the interaction of hexavalent chromium [Cr(VI)] with diphenylcarbazide in microfluidic chips (μFIA) with thermal-lens microscopic detection were selected. The characteristic feature of the applied flow scheme is the injection of the reagent into the stream containing the test metal, which enables in-field and real-time monitoring of Cr(VI) simply by flowing the sample continuously through the microchip. The limit of detection of Cr(VI) under the selected conditions (signal generating wavelength, 514.5 nm; excitation power, 100 mW; detection position, 10 cm downstream from the mixing zone of the microchip; flow rate 10 μL min–1; injection volume, 1.4 μL) is 15 ng mL–1 (2.9 × 10–7 mol L–1). The linear range is 40 ng mL–1 – 10 μg mL–1 with a relative standard deviation no higher than 10% in the concentration range 0.1–1 μg mL–1. The online monitoring by this scheme provides the possibility of up to 360 analyses per hour.
Ključne besede: Photothermal lensing, thermal-lens microscopic detection, microfluidic applications, μFIA, hexavalent chromium, diphenylcarbazide
Objavljeno v RUNG: 12.12.2016; Ogledov: 4428; Prenosov: 0
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64.
Determination of bioactive compounds in food samples by thermal lens microscopy
Jelena Topić, Mojca Žorž, Valeria Guzsvány, Branka Mozetič Vodopivec, Dorota Korte, Mladen Franko, 2016, objavljeni povzetek znanstvenega prispevka na konferenci

Ključne besede: thermal lens microscopy, food samples, bioactive compounds
Objavljeno v RUNG: 08.11.2016; Ogledov: 5398; Prenosov: 0
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65.
Determination of biogenic amines by thermal lens microscopic detection of enzymatically released ammonium
Mojca Žorž, Mladen Franko, 2016, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Biogenic amines (BAs) are organic amines present in meat, fish, dairy produce and wine due to the breakdown of amino acids, catalysed by microbial decarboxylases. BAs determination in food is important not only because of possible toxicological effects such as nausea, sweating and headache but also due to their possible role as indicators of food spoilage. Chromatographic methods are traditionally applied for determination of BAs in food [1], which usually require preliminary operations for sample pre-treatment that are laborious and difficult to automate. On the other hand, screening analytical systems provide simple, low cost and rapid analysis with the possibility of subjecting high number of samples to the screening system in a short time [2]. In this work we present a novel method for screening determination of BAs using a microfluidic system with the detection by highly sensitive thermal lens microscope (μFIA-TLM). Four biogenic amines (putrescine, cadaverine, histamine and tyramine) were subjected to enzymatic catalysis by transglutaminase, where ammonia was released as a product of acyl transfer reaction between the peptide bound glutamine (Gln) and the amino group of BAs. Ammonia was further transformed into indophenol blue by the Berthelot reaction. The coloured product was detected in batch (static) mode in a 100 μm sample cell or in μFIA (flowing) mode in a microchip with the same optical path length. The detection was performed on a TLM system applying a solid-state diode as an excitation source (660 nm). Organic solvents were tested for signal enhancement. For evaluation of the sensitivity and determination of LOD values (S/N = 3 basis), the NH4Cl standard solution was applied in Berthelot reaction with further detection on TLM system. The LODs for NH4+ in batch mode and in μFIA were 24 μg/L and 109 μg/L, respectively. Both LOD values are lower than the LOD achieved with conventional spectrophotometry (180 μg/L). When mixtures of the indophenol standard solutions and EtOH in the ratio of 1:1 were prepared the LOD in batch mode was improved to 3 μg/L, achieving 60-times improvement compared to spectrophotometry.
Ključne besede: Biogenic amines, Thermal lens microscopy, microfluidics, translgutaminase
Objavljeno v RUNG: 05.07.2016; Ogledov: 5073; Prenosov: 0
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66.
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: 5483; Prenosov: 0

67.
Thermal Lens Spectrometry: Still a Technique on the Horizon
Mingqiang Liu, Mladen Franko, 2016, objavljeni znanstveni prispevek na konferenci

Opis: In this article the historical development of thermal lens spectrometry (TLS) is briefly reviewed for introduction. In continuation, the emphasis is on the recent progresses of TLS for measurements in ensembled sample cells and in microfluidic flow injection systems. Novel theories, instrumentations and their applications for high sample throughput environmental, chemical and biomedical analysis, particularly in micro space, are presented. Discussions are given on the limitations of present TLS systems, that open new horizons for future progress of this technique, which has already found place among routine techniques for chemical analysis. In the last part, proposals for the future development of TLS toward advanced applications in new research fields are presented.
Ključne besede: Thermal lens spectrometry, Microfluidic chip, Chemical analysis, Environmental monitoring, Biomedical assay
Objavljeno v RUNG: 17.05.2016; Ogledov: 4924; Prenosov: 0
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68.
Thermal lens spectrometry - still a technique on the horizon?
Mladen Franko, 2015

Opis: 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.
Ključne besede: Thermal lens spectrometry, applications, Liquid chromatography, flow injection analysis, bioanalytical methods
Objavljeno v RUNG: 29.03.2016; Ogledov: 6422; Prenosov: 0
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