Diode lasers and practical trace analysis

Imasaka, Totaro; Ishibashi, Nobuhiko

doi:10.1021/ac00205a001

Cited by 30 publications

(7 citation statements)

References 18 publications

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“…Ideally, such materials would not only detect VOCs below the part per million (ppm) level but would also show a unique response for each VOC. Responsive compounds that report in the NIR region may be particularly promising because of intrinsic low level background interferences …”

Section: Introductionmentioning

confidence: 99%

“Vapochromic” Compounds as Environmental Sensors. 2. Synthesis and Near-Infrared and Infrared Spectroscopy Studies of [Pt(arylisocyanide)₄][Pt(CN)₄] upon Exposure to Volatile Organic Compound Vapors

et al. 1997

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The synthesis, characterization, and vis−NIR−IR vapochromic/spectroscopic studies are reported for isocyanide compounds of the form [Pt(arylisocyanide)4][Pt(CN)4] (where arylisocyanide = p-CNC6H4C n H2n+1; n = 1, 6, 10, 12, 14). The dark blue, solid materials change color in the NIR (near-infrared) spectral region upon exposure to the ambient room-temperature vapor pressure of volatile organic compounds (VOCs). At room temperature the PtPt compounds exhibit strong solid-state absorption and emission bands in the NIR region of the spectrum that are red-shifted from similar bands in the PtPd analogues; (n = 1, λmax abs = 744, λmax emit = 958; n = 6, λmax abs = 841, λmax emit = 910; n = 10, λmax abs = 746, λmax emit = 944; n = 12, λmax abs = 764, λmax emit = 912; n = 14, λmax abs = 690, λmax emit = 876 nm). The positions of these broad bands depend on the number of carbons in the alkyl substituent. The absorption and emission bands for the solid material (n = 10 compound) also exhibit a substantial red-shift upon cooling to 77 K (λmax abs (293 K) = 746; λmax emit (293 K) = 944; λmax abs (77 K) = 846; λmax emit (77 K) = 1094 nm) that is consistent with an alternating cation−anion stacked structure. Qualitatively, compounds with n > 6 respond well to nonpolar VOCs; the n = 1, 6 compounds respond better to polar VOCs. The shifts observed for λmax abs (at 293 K) are on the order of 700 cm-1 and are 2−3 times greater than those exhibited by the PtPd analogue compounds under identical conditions. The n = 10 compound is the most responsive; the positions of the vis−NIR band in the presence of several solvent vapors are as follows: none, 746 nm; methanol, 757; ethanol, 782; 2-propanol, 782; diethyl ether, 787; acetonitrile, 809; hexanes, 775; acetone, 800; benzene, 801; dichloromethane, 811; chloroform, 837. No response was observed for water vapor. IR studies of films of the n = 10 compound on an ATR crystal show that the sorption of VOC by the solid causes no change in the ν(CN) isocyanide stretching frequency but in some cases a substantial shift (0−15 cm-1) in ν(CN) of the cyanide stretch is observed. When the n = 10 compound contacts VOCs capable of H-bonding with the Pt(CN)4 2- anion, two cyanide stretches are observed. All the spectroscopic data suggest that the VOC penetrates the solid and interacts with the linear chain chromophore to cause the spectral shifts in the vis−NIR−IR spectral regions. The vapochromic shifts are suggested to be due to dipole−dipole and/or H-bonding interactions between the Pt(CN)4 2- anion and polar VOCs. For nonpolar VOCs, lypophilic interactions between the VOC and the isocyanide ligands that cause no change in the ν(CN) stretching region must cause the NIR vapochromism observed. The absence of a vapochromic response for water vapor is suggested to a...

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Section: Introductionmentioning

confidence: 99%

“Vapochromic” Compounds as Environmental Sensors. 2. Synthesis and Near-Infrared and Infrared Spectroscopy Studies of [Pt(arylisocyanide)₄][Pt(CN)₄] upon Exposure to Volatile Organic Compound Vapors

et al. 1997

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“…Most of the commercially available derivatization reagents have therefore been developed for this wavelength region . Although, very low mass detection limits (femtomole and attomole levels) have been achieved in this region, the sensitivity of analysis is limited by Raman scatter . Additionally, endogenous porphyrin-type molecules provide high background fluorescence which results in reduced selectivity when analysis is conducted in biological matrixes .…”

mentioning

confidence: 99%

Visible Diode Laser-Induced Fluorescence Detection of Phenylacetic Acid in Plasma Derivatized with Nile Blue and Using Precolumn Phase Transfer Catalysis

Rahavendran

Karnes

1997

Anal. Chem.

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This study reports the application of Nile blue (NB), a farred oxazine label, as a precolumn derivatization reagent for the measurement of free levels of phenylacetic acid (PAA) in plasma. The measurement of PAA in psychiatric populations is important because it provides a marker for 2-phenylethylamine (PEA), which has been implicated in the pathogenesis of schizophrenia and major depression. PAA was derivatized with NB through an amide linkage in the presence of 2-chloro-1-methylpyridinium iodide (carboxylic acid activator, CMP) and triethylamine (base catalyst, TEA), respectively. The formation of the NB-PAA derivative was confirmed using normal phase and reversed phase thin-layer chromatography, reversed phase liquid chromatography, and electrospray mass spectrometry. The formation of the NB-PAA derivative was optimized using a sequential single factor approach. The optimal conditions for the formation and chromatographic separation of the derivative were determined to be 8.0 nmol/mL NB, 390 nmol/mL CMP, 2 mumol/mL TEA, a reaction time of 45 min, and a reaction temperature of 25 degrees C. This derivatization scheme was performed in a phase transfer catalysis mode that enabled the simultaneous extraction, preconcentration, and derivatization of the analyte in a single step. The limit of derivatization of PAA was determined to be 1.0 x 10(-9) M in phosphate-buffered saline, a PAA-free matrix. This derivatization was limited not by the kinetics of the reaction but by the chromatographic separation of the derivative from a side reaction product. The method was used to estimate endogenous free levels of PAA in human plasma samples. The levels of PAA in four sources of plasma were determined to be within 30-70 ng/mL using the method of standard addition and reflected levels that have been reported in the literature. The limit of detection of the derivative was determined to be 7.33 x 10(-11) M using a laboratory-constructed HPLC-VDLIF detector.

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“…Of the available light sources, diode lasers emitting at 670 and 780 nm are preferred due to their high intensity, low cost and suitable performance when waveguides are to be used. However, the lack of commercial chromoionophores, which display absorption bands in the far viseNIR region of the electromagnetic spectrum, is a significant hindrance to the exploitation of integrated optical sensors [16,17] and, only very few types of dyes with such characteristics have been successfully applied in bulk optodes and integrated sensors [18]. Therefore, some promising new types of chromoionophores have been synthesised in our research group.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of new norcyanine dyes and their application as pH chromoionophores in optical sensors

et al. 2007

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Diode lasers and practical trace analysis

Cited by 30 publications

References 18 publications

“Vapochromic” Compounds as Environmental Sensors. 2. Synthesis and Near-Infrared and Infrared Spectroscopy Studies of [Pt(arylisocyanide)₄][Pt(CN)₄] upon Exposure to Volatile Organic Compound Vapors

“Vapochromic” Compounds as Environmental Sensors. 2. Synthesis and Near-Infrared and Infrared Spectroscopy Studies of [Pt(arylisocyanide)₄][Pt(CN)₄] upon Exposure to Volatile Organic Compound Vapors

Visible Diode Laser-Induced Fluorescence Detection of Phenylacetic Acid in Plasma Derivatized with Nile Blue and Using Precolumn Phase Transfer Catalysis

Characterisation of new norcyanine dyes and their application as pH chromoionophores in optical sensors

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Diode lasers and practical trace analysis

Cited by 30 publications

References 18 publications

“Vapochromic” Compounds as Environmental Sensors. 2. Synthesis and Near-Infrared and Infrared Spectroscopy Studies of [Pt(arylisocyanide)4][Pt(CN)4] upon Exposure to Volatile Organic Compound Vapors

“Vapochromic” Compounds as Environmental Sensors. 2. Synthesis and Near-Infrared and Infrared Spectroscopy Studies of [Pt(arylisocyanide)4][Pt(CN)4] upon Exposure to Volatile Organic Compound Vapors

Visible Diode Laser-Induced Fluorescence Detection of Phenylacetic Acid in Plasma Derivatized with Nile Blue and Using Precolumn Phase Transfer Catalysis

Characterisation of new norcyanine dyes and their application as pH chromoionophores in optical sensors

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“Vapochromic” Compounds as Environmental Sensors. 2. Synthesis and Near-Infrared and Infrared Spectroscopy Studies of [Pt(arylisocyanide)₄][Pt(CN)₄] upon Exposure to Volatile Organic Compound Vapors

“Vapochromic” Compounds as Environmental Sensors. 2. Synthesis and Near-Infrared and Infrared Spectroscopy Studies of [Pt(arylisocyanide)₄][Pt(CN)₄] upon Exposure to Volatile Organic Compound Vapors