Direct detection of gradient-eluted non-labeled amino acids using micro-HPLC with ultraviolet thermal lensing

Katae, Hitoshi; Hirashima, Satoshi; Harata, Akira

doi:10.1088/1742-6596/214/1/012122

Cited by 3 publications

(2 citation statements)

References 13 publications

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“…However, photothermal techniques are ill suited for the gradient separation mode: the detection sensitivity under gradient separation is generally lower than that under isocratic separation. 4,20 This is mainly because locally incomplete mixing of different solvents results in turbulence in the thermal conductivity and temperature coefficient of the refractive index, causing noise in the photothermal signals. Molecular diffusiondominated uniform mixture formation is quadratically faster in a smaller space.…”

Section: Resultsmentioning

confidence: 99%

Ultraviolet-Excitation Photothermal Heterodyne Interferometer as a Micro-HPLC Detector

2019

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The first demonstration of a photothermal heterodyne interferometer (PHI) combined with micro-HPLC (high-performance liquid chromatography) is reported. A semiconductor laser (375 nm) was used for excitation, and the temperature change caused by heat released from photoexcited species was detected with a He-Ne laser (632.8 nm). The temperaturedependent refractive index change of the solvent modified the optical path of the probe beam. The phase difference between two arms of the interferometer, one passing through the heated sample and another as a reference, was sensitively detected with the PHI. The nitro-polycyclic aromatic hydrocarbon and vitamin mixture separated via micro-HPLC was successfully detected with the PHI as well as a UV detector. The detection limit of the PHI for riboflavin in the absorbance units was 77 times better than that of the commercial UV detector. The detection limit of the PHI with a small flow cell (6 nL) was the same as that with a large flow cell (18 nL) for 1-nitropyrene.

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Section: Resultsmentioning

confidence: 99%

Ultraviolet-Excitation Photothermal Heterodyne Interferometer as a Micro-HPLC Detector

2019

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“…In the UV region, a frequency-doubled Arþ laser was used for detection of nitroaromatic compounds in contaminated water by a crossed-beam TL system at 257 nm after separation by micellar electrokinetic chromatography (Ragozina et al, 2002), and for detection of neonicotinoids by a TLS system at 244 nm after separation by LC (Guzsv any et al, 2007); the third harmonics (261 nm) of a mode-locked Ti: sapphire laser has been used in a TLM for imaging yeast fungus cells (Harata et al, 2007), and the fourth harmonics (214 nm) was employed in a crossed-beam TL system coupled with micro-HPLC for direct detection of non-labeled amino acids (Katae et al, 2010). Hiki et al (2006) developed a UV-TLM using a high-repetition-frequency (80 kHz) 266 nm UV pulsed laser for detection of nonfluorescent molecules on a microchip.…”

Section: Improvements Of Specificitymentioning

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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Ultraviolet and Deep-Ultraviolet Excitation Photothermal Heterodyne Interferometer Combined with Semi-Micro HPLC

et al. 2020

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A detection system consisting of a photothermal heterodyne interferometer (PHI) combined with semi-micro HPLC (high-performance liquid chromatography) has been designed and investigated. An ultraviolet (UV) or deep-UV laser emitting at 375 nm or 213 nm, respectively, was used for the excitation of nitro-polycyclic aromatic hydrocarbons (NPAHs) and amino acids. Photothermally induced change in the refractive index of the solvent causes an optical phase difference between two arms of the interferometer, one beam passing through the photoexcited region and another as a reference, which was sensitively detected with the PHI. Separation and detection of NPAHs and amino acids were successfully demonstrated via semi-micro HPLC with the PHI and a UV detector. The detection limits of the UV-excitation PHI for NPAHs were 1.2-5.2 times better than that of the commercial UV detector, although the first demonstration of deep-UV excitation suffered from significant baseline fluctuation.

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Direct detection of gradient-eluted non-labeled amino acids using micro-HPLC with ultraviolet thermal lensing

Cited by 3 publications

References 13 publications

Ultraviolet-Excitation Photothermal Heterodyne Interferometer as a Micro-HPLC Detector

Ultraviolet-Excitation Photothermal Heterodyne Interferometer as a Micro-HPLC Detector

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

Ultraviolet and Deep-Ultraviolet Excitation Photothermal Heterodyne Interferometer Combined with Semi-Micro HPLC

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