Effect of organic solvents in the on-line thermal lens spectrometric detection of chromium(III) and chromium(VI) after ion chromatographic separation

Šikovec, Mateja; Franko, Mladen; Novič, Milko; Veber, Marjan

doi:10.1016/s0021-9673(01)00611-2

Cited by 37 publications

(16 citation statements)

References 15 publications

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“…33,34 The value of normalization factor was 1.72, which is in good agreement with the theoretical value of 1.86 (found by dividing ((∂n/∂T)/k) ratios for n-octane and methanol). Fig.…”

Section: Resultssupporting

confidence: 87%

Microfluidic droplet-based liquid–liquid extraction: online model validation

et al. 2015

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Droplet-based liquid-liquid extraction in a microchannel was studied, both theoretically and experimentally. A full 3D mathematical model, incorporating convection and diffusion in all spatial directions along with the velocity profile, was developed to depict the governing transport characteristics of droplet-based microfluidics. The finite elements method, as the most common macroscale simulation technique, was used to solve the set of differential equations regarding conservation of moment, mass and solute concentration in a two-domain system coupled by interfacial surface of droplet-based flow pattern. The model was numerically verified and validated online by following the concentrations of a solute in two phases within the microchannel. The relative azobenzene concentration profiles in a methanol/n-octane two-phase system at different positions along the channel length were retrieved by means of a thermal lens microscopic (TLM) technique coupled to a microfluidic system, which gave results of high spatial and temporal resolution. Very good agreement between model calculations and online experimental data was achieved without applying any fitting procedure to the model parameters.

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“…33,34 The value of normalization factor was 1.72, which is in good agreement with the theoretical value of 1.86 (found by dividing ((∂n/∂T)/k) ratios for n-octane and methanol). Fig.…”

Section: Resultssupporting

confidence: 87%

Microfluidic droplet-based liquid–liquid extraction: online model validation

et al. 2015

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“…As a result of this and other already mentioned advantages of FIA, the LOD for TLS determination of Cr(VI) was reduced down to 67 ng/L, despite some loss of sensitivity due to the effects of the flow and without the addition of organic solvents for improvement of thermooptical properties (91). This represents an improvement by almost a factor of two compared to the batch mode measurement (28) and best reported LODs for determination of Cr(VI) by IC-TLS (54). The main difficulty in the FIA-TLS detection of Cr(VI) was, however, encountered in the differences of thermooptical properties of sample (carrier solution) and the injected DPC reagent (20 mL) prepared in 4% H 3 PO 4 with 8% acetone.…”

Section: Tls Detection In Fia and Separation Techniques 373mentioning

confidence: 61%

Thermal Lens Spectrometric Detection in Flow Injection Analysis and Separation Techniques

Franko

2008

Applied Spectroscopy Reviews

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Recent applications of thermal lens spectrometry in liquid chromatography (HPLC, ion chromatography), capillary electrophoresis, and flow injection analysis are reviewed. Possible effects of performing TLS measurements in flows are discussed initially for different TLS configurations. The emphasis is given to the analysis of real samples, and the performances of various detection schemes in combination with chromatographic techniques and FIA are discussed particularly in terms of sensitivity, sample throughput, and eventual interferences from complex matrices. Coaxial TLS detection with continuous wave excitation is most suitable for detection in HPLC, ion chromatography, and FIA using long-path length cells, when large volume samples are available. On the other hand, transverse or crossed beam TLS was found most suitable for detection in CE where it provides low absolute LODs, which are lowered even further by thermal lens microscopy on microchips, where the capability of detecting a single molecule in the detection volume was demonstrated.

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“…Organic solvents have much higher dn/dT and lower k than water. Addition of water-mixable solvents such as acetonitrile to the eluent and postcolumn reagent (30% and 60% v/v, respectively) enabled simultaneous determination of Cr(VI) at 0.1 mg/L and of Cr(III) at 10 mg/L levels by ion chromatography (IC) with TLS detector ( Sikovec et al, 2001). The addition of acetonitrile provided 5.4 times higher enhancement factor than an aqueous eluent.…”

Section: Selection Of Solventmentioning

confidence: 99%

Progress in Thermal Lens Spectrometry and Its Applications in Microscale Analytical Devices

Liu

Franko

2014

Critical Reviews in Analytical Chemistry

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Development of thermal lens spectrometry (TLS) as a micro space-compatible photothermal technique and its applications for analysis of different chemical compounds in micro space and particularly in microfluidic systems are reviewed. Theoretical treatment of TLS in micro space has evolved from simply following conventional theory and predictions in macro space to employing a more accurate theory where impacts of the excitation source (Gaussian laser, top-hat incoherent light source, beam divergence, power density), detection scheme (probe beam waist, mode-mismatching degree), sample flow, and sample cell (top/bottom layers, side wall) on the TL signal are included. Noise sources (light sources, sample status, detector) in TLS systems have been analyzed, and optimum pinhole-to-beam radius ratio is suggested for the maximum signal-to-noise ratio. With different excitation light sources from ultraviolet, to visible, to near-infrared regions and coupled with microfluidic devices, these TLS instruments with good temporal and spatial resolution have found many applications for highly sensitive and/or high-throughput detection of chemical or biochemical analytes, for cell imaging or single particle/molecule detection, and for characterization of molecular diffusion in single- or two-phase systems. Prospects and challenges of TLS for future applications in microchemical analysis are discussed.

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Effect of organic solvents in the on-line thermal lens spectrometric detection of chromium(III) and chromium(VI) after ion chromatographic separation

Cited by 37 publications

References 15 publications

Microfluidic droplet-based liquid–liquid extraction: online model validation

Microfluidic droplet-based liquid–liquid extraction: online model validation

Thermal Lens Spectrometric Detection in Flow Injection Analysis and Separation Techniques

Progress in Thermal Lens Spectrometry and Its Applications in Microscale Analytical Devices

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