Detection luminescence spectrometry

A number of less commonly used analytical techniques are available for determining PAHs. These include synchronous luminescence spectroscopy (SLS), resonant (R)/nonresonant (NR)-synchronous scan luminescence (SSL) spectrometry, room temperature phosphorescence (RTP), ultraviolet-resonance Raman spectroscopy (UV-RRS), x-ray excited optical luminescence spectroscopy (XEOL), laser-induced molecular fluorescence (LIMP), supersonic jet/laser induced fluorescence (SSJ/LIF), low- temperature fluorescence spectroscopy (LTFS), high-resolution low-temperature spectrofluorometry, low-temperature molecular luminescence spectrometry (LT-MLS), and supersonic jet spectroscopy/capillary supercritical fluid chromatography (SJS/SFC) Asher 1984 Garrigues and Ewald 1987 Goates et al. 1989 Jones et al. 1988 Lai et al. 1990 Lamotte et al. 1985 Lin et al. 1991 Popl et al. 1975 Richardson and Ando 1977 Saber et al. 1991 Vo-Dinh et al. 1984 Vo- Dinh and Abbott 1984 Vo-Dinh 1981 Woo et al. 1980). More recent methods for the determination of PAHs in environmental samples include GC-MS with stable isotope dilution calibration (Bushby et al. 1993), capillary electrophoresis with UV-laser excited fluorescence detection (Nie et al. 1993), and laser desorption laser photoionization time-of-flight mass spectrometry of direct determination of PAH in solid waste matrices (Dale et al. 1993). 

Low temperature-molecular luminescence spectrometry (LT-MLS), SLS, and HPLC/fluorescence detection have been used to measure pyrene in broiled hamburger (Jones et al. 1988). A comparison of the three methods showed that sensitivity for all three methods was in the low-ppb range and that all methods were comparably reproducible (6-9% RSD). Adequate recovery (75-85%) was obtained from the extraction procedure for all three methods. While HPLC is the least expensive and easiest to operate, it has the longest analysis time (30 minutes), and it provides the least resolution of components. LT-MLS is the fastest technique (5 minutes), and it gives mores spectral information than the other two methods. SLS, with an analysis time of 15 minutes, offers no real advantages over LT-MLS other than cost of equipment. 

In the past, molecular luminescence spectrometry was always conducted with single channel systems involving a photomultiplier tube (PMT) as the detector. The availability of multichannel detectors with internal gain has provided a new powerful tool for luminescence measurements, and several types of applications have been reported (1-15). This paper is concerned with the application of an intensified diode array dynamic molecular fluorescence and chemiluminescence measurements. In this paper the types of measurements and analytical systems for which multichannel detectors are used in our laboratory are introduced. Next the specific IDA system used is presented along with important hardware and software considerations. Third, the characteristics of the IDA detector are reviewed to give some perspective about its influence on the quality of measurements. Finally, some typical applications to chemical systems are presented to illustrate the advantages of multichannel detection. 

Molecular luminescence spectrometry, especially molecular fluorescence spectrometry, has become estabhshed as a routine technique in many analytical applications. In many cases, molecular luminescence spectrometry can yield a lower detection limit and greater selectivity than molecular absorption spectrometry. However, although most compounds exhibit strong fluorescence or... 

In addition, a number of advanced analytical techniques, such as low temperature luminescence spectroscopy, tandem mass spectrometry (MS/MS), Fourier-Transform IR-spectroscopy and nuclear magnetic resonance spectrometry have been successfully applied to PAH analysis. For instance, low temperature luminescence spectrometry, sometimes in combination with laser excitation, was used for the analysis of PAH in various matrices without prior separation, which is attractive especially for screening or finger-printing purposes (10, 73). However, a wider application for routine analysis is at present inhibited by the limited availability of the required equipment. The same remark applies to tandem mass spectrometry, FT-IR spectroscopy and NMR. All three techniques, however, are increasingly used for the detection and identification of novel PAH species and derivatives and efforts are continuing towards coupling IR and NMR as detectors to GC and HPLC (74) respectively. 

The equipment for screening passengers and baggage is designed to identify trace amounts of specific known explosives. Analytic trace detection is conducted using mass spectrometry, gas chromatography, chemical luminescence, or ion mobility spectrometry. Ion mobility spectrometry is most commonly used. Novel explosive material wiU not be probably detected by these systems. Information on the equipment s technical performance is not publicly available because of security reasons, which inhibits an independent analysis of equipment s performance [160]. 

Several other analytical procedures exist in which solvent extraction may be applied. Thus extraction has been used in a limited number of analyses with procedures such as (1) luminescence (fluorimetry), where, for example, the detection limit of rhodamine complexes of gallium or indium can be increased by extraction [28] (2) electron spin resonance using a spin-labelled extractant [29] and (3) mass spectrometry, where an organic extract of the analyte is evaporated onto pure AI2O3 before analysis [30]. 

Maupin, C. L. Riehl, J. P. Circularly polarized luminescence and fluorescence detected circular dichroism. In Encyclopedia of Spectroscopy and Spectrometry, Lindon, J. C. Trantner, G. E. Holmes, J. L., Eds. Academic Press, 2000 pp 319-326. 

In the specific case of the determination of trace amounts of actinides, it is interesting to compare the results obtained by TRES to those obtained by other techniques. This very brief presentation is based on a very detailed and comprehensive lecture on radioactive ultra-trace determination in the environment (Aupiais, 2001, in French). In order to detect radioactive traces in environmental samples, various techniques are available (a and ft liquid scintillation, y spectrometry, mass spectrometry,. ..), which most of the time are coupled to a preconcentration of the sample. Such methods allow isotope discrimination, which is impossible with TRES. Another restriction of TRES as compared to the other techniques available is that TRES is strictly limited to luminescent elements. On the other hand, liquid scintillation is a rather time-consuming method as compared to TRES. For example, detection limits with a liquid scintillation are equal to 2 x 10-10 mol for 238U and 9 x 10-19 mol for 244Cm but the acquisition time is on the order of a few days, to be compared with TRES acquisition times of a few minutes. In the case of Cm, the advantage of a liquid scintillation is clear but TRES appears to be competitive in the case of U, if no isotopic discrimination is required. 

Chromatographic techniques are the main methods that have been used to separate, detect, and identify organic components of FDR.152 162 Other methods considered include molecular luminescence,163 infrared spectroscopy,164 Raman spectroscopy,165 electron spin response spectrometry,166 microchemical crystal tests,167 168 ultraviolet spectroscopy/nuclear magnetic resonance/polarography.169... 

The theory of rotation effects on prolate luminescent molecules in solution and its experimental verification have been developed and compared. Generalized diffusion equations for the rotational motion of an asymmetric rigid motor have been used to given an expression for steady-state fluorescence depolarization. " The radiationless transition from the first excited singlet state of Eosin has been measured by optoacoustic relaxation, and the absolute fluorescence quantum yields of organic dyes in poly(vinyl alcohol) have also been measured by the photoacoustic method. The accuracy of the method has been discussed in the latter paper. Actinometry in flash photolysis experiments has been assisted by new measurements on the extinction coefficient of triplet benzophenone. Matrix-isolation fluorescence spectrometry has been used to detect polycyclic aromatic hydrocarbons from gas chromatography. ... 

While luminescence in vapor-deposited matrices accordingly should be a powerful technique for detection and quantitation of subnanogram quantities of PAH in complex samples, it suffers from two major limitations. First, it is obviously limited to the detection of molecules which fluoresce or phosphoresce, and a number of important constituents of liquid fuels (especially nitrogen heterocyclics) luminesce weakly, if at all. Second, the identification of a specific sample constituent by fluorescence (or phosphorescence) spectrometry is strictly an exercise in empirical peak matching of the unknown spectrum against standard fluorescence spectra of pure compounds in a hbrary. It is virtually impossible to assign a structure to an unknown species a priori from its fluorescence spectrum qualitative analysis by fluorometry depends upon the availabihty of a standard spectrum of every possible sample constituent of interest. Inasmuch as this latter condition cannot be satisfied (particularly in view of the paucity of standard samples of many important PAH), it is apparent that fluorescence spectrometry can seldom, if ever, provide a complete characterization of the polycyclic aromatic content of a complex sample. 

Apart from these methods, pulse radiolysis, ESR and NMR spectroscopy, mass spectrometry, optical, chromatographic, and luminescent methods are also used. To study the kinetics and mechanism of the reactions in the early stages of polymerization pulse radiolysis with spectroscopic detection is often used [2-4],... 

Most optical detection methods for biosensors are based on ultra-violet (UV) absorption spectrometry, emission spectroscopic measurement of fluorescence and luminescence, and Raman spectroscopy. However, surface plasmon resonance (SPR) has quickly been widely adopted as a nonlabeling technique that provides attractive advantages. Fueled by numerous new nanomateiials, their unique, SPR-based or related detection techniques are increasingly being investigated [28-31]. 

Ultraviolet and luminescence (fluorescence and chemiluminescence) spectrometry provides sensitive and selective detection of PAHs. 

Ackerman, A.H. and R.J. Hurtuhise, Methods for Coating Filter Paper for Solid-Phase Microextraction with Luminescence Detection and Characterization of the Coated Filter Paper by Infrared Spectrometry. Anal. Chim. Acta, 2002. 474 77-89. 

McKelvie, 2008). Detection methods have included UV/Vis spectroscopy (the largest number of applications for its robustness, versatility, simplicity, and low cost), luminescence and chemiluminescence (CL) (which offer low detection limits and high sensitivity, being therefore especially favored for biological, biochemical, and trace analysis), atomic absorption and emission spectroscopy (which benefit enormously from automated sample pretreatment, used for matrix removal and analyte accumulation), electrochemistry (pH, fluoride ion selective electrodes, stripping voltammetry and conductivity), turbidimetry, vibrational spectroscopy (Fourier transform infrared spectroscopy [FTIR] and Raman) and mass spectrometry. 

See also Biochemical Applications of Raman Spectroscopy Biomacromolecular Applications of Circular Dichroism and ORD Carbohydrates Studied by NMR Circularly Polarized Luminescence and Fluorescence Detected Circular Dichroism Induced Circular Dichroism Magnetic Circular Dichroism, Theory Nucleic Acids and Nucleotides Studied Using Mass Spectrometry Organometallics Studied Using Mass Spectrometry Polymer Applications of IR and Raman Spectroscopy Proteins Studied Using NMR Spectroscopy Vibrational CD Spectrometers Vibrational CD, Theory. 

Maupin CL, Riehl JP. Circularly Polarized Luminescence and Fluorescence Detected Circular Dichroism. In Lindon JC, Trantner GE, Holmes JL, editors. Encyclopedia of Spectroscopy and Spectrometry Academic Press, New York 2000, pp. 319-326. 

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