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51.
Determination of total ChE and AChE activity in human serum by FIA-TLS
Andrej Jerkič, Tjaša Birsa, Dorota Korte, Martina Bergant Marušič, Mladen Franko, 2019, published scientific conference contribution abstract

Keywords: acetylcholinesterase, FIA-TLS, butyrilcholinesterase
Published in RUNG: 19.12.2019; Views: 3244; Downloads: 0
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52.
Determination of Iron in Environmental Water Samples by FIA-TLS
Miha Tomšič, Leja Goljat, Hanna Budasheva, Dorota Korte, Arne Bratkič, Mladen Franko, 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.
Keywords: Flow injection analysis, iron concentration, thermal lens spectroscopy
Published in RUNG: 18.12.2019; Views: 3170; Downloads: 105
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53.
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, original scientific article

Abstract: 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.
Keywords: Thermal lens spectrometry, Photothermal detection, Trace determination, Chemical sensor
Published in RUNG: 10.12.2019; Views: 3123; Downloads: 0
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Photothermal spectrophotometer for meaurements of low absorption in liquid samples
J. Akbar, Humberto Cabrera, Dorota Korte, 2019, published scientific conference contribution abstract

Keywords: photothermal spectroscopy techniques, halogen lamps, TL signal
Published in RUNG: 16.07.2019; Views: 3132; Downloads: 0
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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, published scientific conference contribution abstract

Keywords: photothermal techniques, Fe determination
Published in RUNG: 16.07.2019; Views: 3540; Downloads: 0
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