Review on recent applications of the liquid waveguide capillary cell in flow based analysis techniques to enhance the sensitivity of spectroscopic detection methods

Páscoa, Ricardo N.M.J.; Tóth, Ildikó V.; Rangel, António O.S.S.

doi:10.1016/j.aca.2012.05.058

Cited by 54 publications

(24 citation statements)

References 103 publications

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“…Photometry is widely used for trace analysis of liquid samples, because abundant chromogenic reagents and semiconductor optoelectronic devices are available 1 2 3 4 5 . In comparison with conventional cuvette-based absorbance detection, liquid waveguide capillary (LWC) can provide long optical-path (up to several meters) for ultra-sensitive detection while retaining small sample volume, by confining the probe light inside the capillary via total internal reflection (TIR) 1 2 3 4 5 . However, the optical-path is only nearly equal to the physical length of LWC without further enhancement 3 6 , and increase of LWC length longer than 1.0 m would suffer from high attenuation of light and high risk of gas bubble formation, etc 3 7 .…”

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confidence: 99%

“…In comparison with conventional cuvette-based absorbance detection, liquid waveguide capillary (LWC) can provide long optical-path (up to several meters) for ultra-sensitive detection while retaining small sample volume, by confining the probe light inside the capillary via total internal reflection (TIR) 1 2 3 4 5 . However, the optical-path is only nearly equal to the physical length of LWC without further enhancement 3 6 , and increase of LWC length longer than 1.0 m would suffer from high attenuation of light and high risk of gas bubble formation, etc 3 7 . As for the multi-reflection cell, which was proposed for optical-path enhancement, the improvement on detection limit is only 2.5 fold 8 9 .…”

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confidence: 99%

“…Currently, there are mainly two kinds of LWC, i.e., Teflon AF capillary (whose refractive-index is only ~1.3 and less than that of water), silica capillary coated with Teflon AF or metal films 1 3 4 . The low refractive-index material and large light incident-angle are required for realizing TIR at interface of dielectric materials 3 6 10 . As for Teflon AF capillary, Teflon AF is permeable to gas and could absorb little species in aqueous sample, due to its porous structure 3 11 .…”

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confidence: 99%

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RETRACTED ARTICLE: A compact photometer based on metal-waveguide-capillary: application to detecting glucose of nanomolar concentration

Bai

Huang

Hao

et al. 2015

Sci Rep

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Trace analysis of liquid samples has wide applications in life science and environmental monitor. In this paper, a compact and low-cost photometer based on metal-waveguide-capillary (MWC) was developed for ultra-sensitive absorbance detection. The optical-path can be greatly enhanced and much longer than the physical length of MWC, because the light scattered by the rippled and smooth metal sidewall can be confined inside the capillary regardless of the incident-angle. For the photometer with a 7 cm long MWC, the detection limit is improved ~3000 fold compared with that of commercial spectrophotometer with 1 cm-cuvette, owing to the novel nonlinear optical-path enhancement as well as fast sample switching, and detecting glucose of a concentration as low as 5.12 nM was realized with conventional chromogenic reagent.

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confidence: 99%

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confidence: 99%

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RETRACTED ARTICLE: A compact photometer based on metal-waveguide-capillary: application to detecting glucose of nanomolar concentration

Bai

Huang

Hao

et al. 2015

Sci Rep

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“…The optofluidic detection of particles in liquid waveguide channels has recently grown in significance [1][2][3][4][5][6][7]. The intersecting of solid-core waveguides with liquid-core waveguides enables light-matter interaction, such as fluorescence generation for single molecule detection.…”

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confidence: 99%

3D Hydrodynamic Focusing in Microscale Optofluidic Channels Formed with a Single Sacrificial Layer

et al. 2020

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Optofluidic devices are capable of detecting single molecules, but greater sensitivity and specificity is desired through hydrodynamic focusing (HDF). Three-dimensional (3D) hydrodynamic focusing was implemented in 10-μm scale microchannel cross-sections made with a single sacrificial layer. HDF is achieved using buffer fluid to sheath the sample fluid, requiring four fluid ports to operate by pressure driven flow. A low-pressure chamber, or pit, formed by etching into a substrate, enables volumetric flow ratio-induced focusing at a low flow velocity. The single layer design simplifies surface micromachining and improves device yield by 1.56 times over previous work. The focusing design was integrated with optical waveguides and used in order to analyze fluorescent signals from beads in fluid flow. The implementation of the focusing scheme was found to narrow the distribution of bead velocity and fluorescent signal, giving rise to 33% more consistent signal. Reservoir effects were observed at low operational vacuum pressures and a balance between optofluidic signal variance and intensity was achieved. The implementation of the design in optofluidic sensors will enable higher detection sensitivity and sample specificity.

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“…Thomson‐Bulldis and Karl ; Wu et al ), the MAGIC protocol has been improved (Rimmelin and Moutin ) and applied to freshwater analysis (Anagnostou and Sherrell ). The LWCC method is based on sensitivity amplification using a long‐path (up to 5 m) optical cell, normally made of Teflon AF I/II (Gimbert and Worsfold ; Páscoa et al ). Since its first application by Zhang and Chi (), the LWCC method has been widely utilized in DRP analysis in combination with different flow analysis techniques, as summarized by Zimmer and Cutter ().…”

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confidence: 99%

A simple and cost‐effective manual solid phase extraction method for the determination of nanomolar dissolved reactive phosphorus in aqueous samples

Yuan

Shu

Yuan

et al. 2015

Limnology & Ocean Methods

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Phosphate is a typical limiting nutrient in oligotrophic oceans and its concentration can be as low as the nanomolar level, especially in surface seawater. Different techniques for nanomolar level phosphate determination have been studied, most of which are automatic and high throughput methods based on flow analysis. However, these techniques need expensive commercial or laboratory‐made instruments, and experienced operators. This study reports an operationally convenient, sensitive and practical method for the determination of nanomolar dissolved reactive phosphorus in aqueous samples, based on classic phosphomolybdenum blue chemistry and solid phase extraction methodology. Under acidic conditions, the formed phosphomolybdenum blue can be preconcentrated on a hydrophilic‐lipophilic balance solid phase cartridge, eluted with 0.2 M NaOH, and detected at 700 nm after color recovery with the addition of more reagents. After optimization of the recovery reagents volumes, the effectiveness of the method was evaluated. This simple manual method is sensitive (detection limit of 3.0 nM using 50 mL sample, which can be lowered to ∼ 1 nM by preconcentrating more sample), reproducible (relative standard deviation of 2.6%, n = 81, with different operators), free of interferences from salinity (0–35), silicate (up to 200 μM) and arsenate (up to 100 nM) and suitable for different aqueous matrixes. The effects of a series of phosphorus‐containing compounds (n = 13) were evaluated, with more than half showing hydrolysis during the experiment. This method was applied to determine the phosphate concentration in samples collected from the Western Pacific.

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Review on recent applications of the liquid waveguide capillary cell in flow based analysis techniques to enhance the sensitivity of spectroscopic detection methods

Cited by 54 publications

References 103 publications

RETRACTED ARTICLE: A compact photometer based on metal-waveguide-capillary: application to detecting glucose of nanomolar concentration

RETRACTED ARTICLE: A compact photometer based on metal-waveguide-capillary: application to detecting glucose of nanomolar concentration

3D Hydrodynamic Focusing in Microscale Optofluidic Channels Formed with a Single Sacrificial Layer

A simple and cost‐effective manual solid phase extraction method for the determination of nanomolar dissolved reactive phosphorus in aqueous samples

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