101. 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.
Keywords: Thermal lens spectrometry, applications, Liquid chromatography, flow injection analysis, bioanalytical methods
Published in RUNG: 29.03.2016; Views: 6517; Downloads: 0
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102. 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: 5548; Downloads: 0
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103. Določevanje kroma(VI) v mikrofluidnem sistemu z optotermično mikroskopsko detekcijo : /Sara Malovrh, 2015, undergraduate thesis Abstract: Krom (Cr) spada med kovinske onesnaževalce, katerega učinek na okolje je močno odvisen od oksidacijskega stanja. Za ljudi je problematična njegova šestvalentna oblika Cr(VI), ki je rakotvorna, zato je potreba po hitri detekciji Cr(VI) velika. V diplomski nalogi smo preverjali točnost detekcije Cr(VI) ob prisotnosti različnih presežkov motečih elementov kot so šestvalentni molibden (Mo(VI)), petvalentni vanadij (V(V)), trivalentno železo (Fe(III)) in dvovalentno živo srebro (Hg(II)). Po kolorimetrični reakciji čistega standarda Cr(VI) in raztopin motečih elementov z difenilkarbazidom (DPC) smo za meritev uporabili spektrofotometrijsko metodo (SPEC) in mikroskopijo s toplotnimi lečami v mikrofluidnem sistemu za pretočno injekcijsko analizo (µFIA - TLM). Rezultati so pokazali, da največjo napako pri meritvah povzroči prisotnost V(V). Izvedli smo tudi študijo razpada preiskovanih kompleksov Cr-DPCO, Mo-DPCO, V-DPCO, Fe-DPCO in Hg-DPCO v odvisnosti od moči vzbujevalnega laserja v mikrofluidnem TLS sistemu (TLM). Dokazali smo, da je železov kompleks stabilnejši od ostalih preiskovanih ionskih kompleksov, ki so znani kot fotolabilni. Z izračunom spodnje meje določevanja (LOD) za SPEC in TLM metodo smo pokazali, da je TLM, zaradi nižje LOD vrednosti primernejša metoda za detekcijo nizkih koncentracij Cr(VI) v vzorcu. Analiza vzorcev iz Soče in Ljubljanice je prikazala sliko realnega stanja v, potencialno s Cr(VI), onesnaženi reki.
Keywords: spektrofotometrija, TLS, TLM, fotolabilnost, moteči elementi
Published in RUNG: 30.09.2015; Views: 6788; Downloads: 275
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104. Novel methods for the detection and removal of cyanobacteria and cyanotoxins : dissertationAmbra Delneri, 2014, doctoral dissertation Keywords: cianobakterije, cvetenje bakterij, cianopigmenti, mikrocistin LR, toplotne leče, kompozitni materiali, hitosan, celuloza, disertacije
Published in RUNG: 22.01.2015; Views: 5410; Downloads: 161
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109. Oxidation as a pre-step in determination of organophosphorus compounds by the AChe-TLS bioassayMojca Bavcon Kralj, Polonca Trebše, Mladen Franko, 2006, original scientific article Keywords: analizna kemija, analitska kemija, bioanalitske tehnike, organofosfatni pesticidi, oksidacija, učinkovitost kemijske oksidacije, kemijska analiza, plinska kromatografija na masno detekcijo, GC-MS, spektrometrija na osnovi termičnih leč, AChE-TLS, NBS
Published in RUNG: 15.10.2013; Views: 6538; Downloads: 32
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