Laser-based non-fluorescence detection techniques for liquid separation systems

Beer, Tjipke de; Velthorst, N.H.; Brinkman, U.A.Th.; Gooijer, C.

doi:10.1016/s0021-9673(02)01038-5

Cited by 29 publications

(18 citation statements)

References 168 publications

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“…This behavior of normal-distribution curves for TLS and TLM does not depend on the signal level and was observed for all the solvents used. The parameters of the normal distribution are somewhat degraded under flow conditions, and as expected [21], the electric-field-driven flows show narrower distribution than pressure-driven flows for both TLS and TLM [33,34]. Altogether, we can conclude that parameters of the normal distribution are almost unchanged from TLS to TLM, despite significantly lower amounts of analytes, flow conditions, and instrumentation that is more complicated.…”

Section: Normal Distribution Of the Results Of Thermallens Measurementssupporting

confidence: 81%

Thermooptical detection in microchips: From macro‐ to micro‐scale with enhanced analytical parameters

Smirnova¹,

Проскурнин²,

Bendrysheva³

et al. 2008

Electrophoresis

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In this paper, we compared the methods of photothermal spectroscopy used in different spatial scales, namely thermal-lens spectrometry (TLS) and thermal-lens microscopy (TLM) to enhance the performance parameters in analytical procedures. All of the experimental results were confirmed by theoretical calculation. It was proven that the design for both TLM and TLS, despite a different scale for the effect, is governed by the same signal-generating and probing conditions (probe beam diameter at the sample should be equal to the diameter of the blooming thermal lens), and almost does not depend on the nature of the solvent. Theoretical and experimental instrumental error curves for thermal lensing were coincident. TLM obeys the same law of instrumental error as TLS and shows better repeatability for the same levels of thermal-lens signals or absorbances. TLS is more advantageous for studying low concentrations in bulk, while TLM shows much lower absolute LODs due to better repeatability for low amounts. The behavior of the thermal-lens signal with different flow rates was studied and optimum conditions, with the minimum contribution to total error, were found. These conditions are reproducible, are in agreement with the existing theory of the thermal response in thermal lensing, and do not significantly affect the design of the optimum scheme for setups. TLM showed low LODs in solvent extraction (down to 10(-8) M) and electrokinetic separation (10(-7) M), which were shown to be governed by discussed instrumental regularities, instead of by microchemistry.

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Section: Normal Distribution Of the Results Of Thermallens Measurementssupporting

confidence: 81%

Thermooptical detection in microchips: From macro‐ to micro‐scale with enhanced analytical parameters

Smirnova¹,

Проскурнин²,

Bendrysheva³

et al. 2008

Electrophoresis

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“…[4][5][6] And, finally, the third trend is shifting from a traditional view of thermooptical spectroscopy as a merely "highly sensitive spectrophotometry" to the development of unique techniques that take advantage of all the specific features of thermooptical spectroscopy as a method of investigation. 7,8 In this connection, the primary trend in developing thermooptical spectroscopy lies in its capabilities of facilitating the basic understanding of the processes following laser irradiation in media and their effects on photochemical and optical parameters of analytes and samples. 4,[9][10][11][12][13][14] This area combines the applications of thermooptical spectroscopy that highlight its unique properties as a method of analytical chemistry.…”

mentioning

confidence: 99%

Sensitivity Enhancement of Thermal-Lens Spectrometry Using Laser-Induced Precipitation

et al. 2009

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The possibility of thermal lensing of dynamically emerging light-absorbing layers at cell surfaces was investigated. Analyte accumulation at a cell surface determines long-term changes in the thermal-lens signal that was used as a source of analytical information to enhance sensitivity of thermal lensing. Considering the rate of accumulation as an additional analytical signal, we achieved a threefold decrease in the limits of detection for 4-aminoazobenzene to the level of 7 mM in a batch mode with the same level of reproducibility. The details of observed thermal-lens signal behavior in cells are discussed. The possibilities to use thermal-lens detection for 4-aminoazobenzene determination in quartz capillaries in flow mode were discussed and a drastic thermal-lens signal enhancement was discovered. The corresponding limit of detection for 4-aminoazobenzene in a flow mode is further decreased to the level of 3 mM.

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“…A more comprehensive review article was compiled by Swinney and Bornhop [4], who apart from the three methods mentioned above also discuss less often used methods such as refractive index change and Raman spectroscopy in detail. Nonfluorescent methods were also discussed in great detail in a review article by de Beer et al [5]. Verpoorte [6] reviewed micrometer scale optical elements for microsystems, including integrated waveguides and light detection on chip.…”

Section: Optical Detectionmentioning

confidence: 99%

Recent developments in detection for microfluidic systems

2004

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Microfluidic systems have become more and more important in the field of analytical chemistry. Detection methods on these microsystems are essential for the identification and quantification of chemical species that are being analyzed. This review concentrates on the latest developments of optical detection methods and mass spectrometry in conjunction with microfluidic systems. Electrochemical methods are discussed in another review in the same issue of this journal. Within the optical detection section, topics such as multiplexed detection and the use of waveguides are discussed. Within the discussion of mass spectrometry, the main focus is on electrospray emitters as interfaces between microsystem and spectrometer. Apart from optical detection and mass spectrometry, other techniques such as flame ionization and nuclear magnetic resonance are also mentioned.

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Laser-based non-fluorescence detection techniques for liquid separation systems

Cited by 29 publications

References 168 publications

Thermooptical detection in microchips: From macro‐ to micro‐scale with enhanced analytical parameters

Thermooptical detection in microchips: From macro‐ to micro‐scale with enhanced analytical parameters

Sensitivity Enhancement of Thermal-Lens Spectrometry Using Laser-Induced Precipitation

Recent developments in detection for microfluidic systems

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