“…Equation 3 reveals the fundamental relationships that are expected between the photopotential and the experimental variables. A semilogarithmic relationship is predicted for the pulse energy, which has been verified experimentally for nitrogen (337 nm, 0.15−0.23 mJ) and excimer (248 nm, 2.4−6.8 mJ) lasers under static conditions. , A semilogarithmic relationship is also expected for the solute concentration, which has been observed for TMPD and other solutes in aqueous and methanolic solutions. , Other variables that affect the instrument-dependent constant K , such as the illuminated area and the separation distance between electrodes, have also been examined under static conditions …”
Section: Resultsmentioning
confidence: 59%
“…Hence, the photovoltaic detection method is well suited for solvents with high water content. This method has also been shown to be capable of detecting photoionization in ionic solutions and buffers of high ionic strength. , This suggests that the photovoltaic detection method is likely to be compatible with the common mobile phases used for reversed-phase liquid chromatography. 3 Dependence of photopotential on solvent dielectric constant.…”
Section: Resultsmentioning
confidence: 96%
“…The relationship between the photopotential and the solute concentration is shown in Figure A for 10-μL injections of aniline, benzaldehyde, and 2-methylvaleraldehyde in methanol at a constant flow rate of 0.3 mL/min. This relationship appears to be semilogarithmic, as predicted by eq 3, and is the same as that observed under static conditions. , The calibration curves are linear for aniline ( r 2 = 0.90), benzaldehyde ( r 2 = 0.85), and 2-methylvaleraldehyde ( r 2 = 0.93), with linear dynamic ranges that exceed 2 orders of magnitude. The minimum detectable concentration is 5 × 10 -6 M (3 ng) for aniline, 1 × 10 -5 M (5 ng) for benzaldehyde, and 1 × 10 -5 M (5 ng) for 2-methylvaleraldehyde in methanol at a signal-to-noise (S/N) ratio of 3.…”
Section: Resultsmentioning
confidence: 99%
“…Consequently, measurements of the photovoltaic response can be readily accomplished in polar or ionic solutions where a photoconductive measurement would be difficult or impossible. More recently, Judge and McGuffin characterized the photovoltaic response with respect to laser pulse energy and wavelength, electrode composition, thickness, and separation distance . In addition, the photovoltaic and photoconductive methods have been compared for detection of solutes in methanol, water, and ionic solutions …”
A photoionization system has been developed for flow injection and liquid chromatographic applications that employs photovoltaic rather than traditional photoconductive detection. This detection system utilizes an excimer laser at 248 nm (5.0 eV) to achieve one-photon excitation in alcoholic, aqueous, and ionic solutions. The photovoltaic response is reported for a variety of solutes including aliphatic and aromatic amines, aldehydes, ketones, carboxylic acids, and halogenated compounds. The photovoltaic method is characterized with respect to solute concentration and flow rate. The detection limit is 5 × 10(-)(6) M (2.3 ng) for aniline in methanol with a linear dynamic range greater than 2 orders of magnitude, which compares favorably to UV-visible absorbance detection. Photovoltaic detection is demonstrated for a series of substituted anilines and aldehydes separated by reversed-phase liquid chromatography.
“…Equation 3 reveals the fundamental relationships that are expected between the photopotential and the experimental variables. A semilogarithmic relationship is predicted for the pulse energy, which has been verified experimentally for nitrogen (337 nm, 0.15−0.23 mJ) and excimer (248 nm, 2.4−6.8 mJ) lasers under static conditions. , A semilogarithmic relationship is also expected for the solute concentration, which has been observed for TMPD and other solutes in aqueous and methanolic solutions. , Other variables that affect the instrument-dependent constant K , such as the illuminated area and the separation distance between electrodes, have also been examined under static conditions …”
Section: Resultsmentioning
confidence: 59%
“…Hence, the photovoltaic detection method is well suited for solvents with high water content. This method has also been shown to be capable of detecting photoionization in ionic solutions and buffers of high ionic strength. , This suggests that the photovoltaic detection method is likely to be compatible with the common mobile phases used for reversed-phase liquid chromatography. 3 Dependence of photopotential on solvent dielectric constant.…”
Section: Resultsmentioning
confidence: 96%
“…The relationship between the photopotential and the solute concentration is shown in Figure A for 10-μL injections of aniline, benzaldehyde, and 2-methylvaleraldehyde in methanol at a constant flow rate of 0.3 mL/min. This relationship appears to be semilogarithmic, as predicted by eq 3, and is the same as that observed under static conditions. , The calibration curves are linear for aniline ( r 2 = 0.90), benzaldehyde ( r 2 = 0.85), and 2-methylvaleraldehyde ( r 2 = 0.93), with linear dynamic ranges that exceed 2 orders of magnitude. The minimum detectable concentration is 5 × 10 -6 M (3 ng) for aniline, 1 × 10 -5 M (5 ng) for benzaldehyde, and 1 × 10 -5 M (5 ng) for 2-methylvaleraldehyde in methanol at a signal-to-noise (S/N) ratio of 3.…”
Section: Resultsmentioning
confidence: 99%
“…Consequently, measurements of the photovoltaic response can be readily accomplished in polar or ionic solutions where a photoconductive measurement would be difficult or impossible. More recently, Judge and McGuffin characterized the photovoltaic response with respect to laser pulse energy and wavelength, electrode composition, thickness, and separation distance . In addition, the photovoltaic and photoconductive methods have been compared for detection of solutes in methanol, water, and ionic solutions …”
A photoionization system has been developed for flow injection and liquid chromatographic applications that employs photovoltaic rather than traditional photoconductive detection. This detection system utilizes an excimer laser at 248 nm (5.0 eV) to achieve one-photon excitation in alcoholic, aqueous, and ionic solutions. The photovoltaic response is reported for a variety of solutes including aliphatic and aromatic amines, aldehydes, ketones, carboxylic acids, and halogenated compounds. The photovoltaic method is characterized with respect to solute concentration and flow rate. The detection limit is 5 × 10(-)(6) M (2.3 ng) for aniline in methanol with a linear dynamic range greater than 2 orders of magnitude, which compares favorably to UV-visible absorbance detection. Photovoltaic detection is demonstrated for a series of substituted anilines and aldehydes separated by reversed-phase liquid chromatography.
“…However, the relatively low sensitivity, narrow dynamic range, and non‐quantitative analysis limit the further application seriously. [ 15–18 ] Therefore, the researchers put lots of effort into exploiting highly sensitive, accurately quantitative chromogenic detection methods for biomolecular analysis. [ 19–22 ]…”
Chromogenic detection of target objects has attracted extensive attention in the academic field with high specificity and sensitivity. Based on color changes in chemical reactions, biomolecular analysis with simple and rapid signal readout in disease diagnosis can be realized. At present, three main mechanisms of chromogenic detection were proposed, including proteases catalysis, enzyme mimics catalysis, and chemical reactions based on inorganic or organic for biomolecular analysis. With the unremitting efforts of scientific researchers, the evolution of chromogenic detection has been developed from the early qualitative detection to the current quantitative detection, accompanied by the improvement of sensitivity. Herein, this paper reviewed the mechanisms and relevant applications of chromogenic detection from the above three aspects, discussed the challenge, and provided a future perspective in this emerging field.
We report a first attempt to use the laser multiphoton ionization method for analysis of trace aromatic compounds on the surface of environmental (soils) and artificial (silica) samples. The measurement setup is composed of a N(2) pulsed laser and a fast conductivity detection system. The technique has been tested for detection of pyrene deposited on moist fine-powdered samples. The observed photoionization signals have indicated a gradual increase in the photoionization current and charge as a function of increasing concentration of pyrene/hexane solutions used for sample contamination. Contaminants have been analyzed in several (organic and inorganic) environmental samples, and a method to compensate for matrix effects is suggested. A contamination model is assumed and applied in order to renormalize all signals and provide an useful calibration plot. This calibration plot provides an upper estimate of pyrene LOD as 35 ng/g.
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