摘要:

A number of new techniques based on spectroscopic principles are being developed for the analysis of PAH as possible alternatives to the chromatographic methods discussed in our earlier review.1The methods discussed in the following sections address themselves to one or both of two broad developmental goals. The first is the need for analytical procedures which are (1) selective for several PAH, (2) capable of detecting subnanogram amounts of PAH, (3) able to provide results on a real-time basis, (4) portable, inexpensive, and easy enough to be automated or run by technicians, all without chromatographic preseparations. Synchronous spectroscopy, room temperature phosphorimetry, and matrix isolation spectroscopy are all techniques which can satisfy these requirements. The second important goal in developing analytical instrumentation is to devise detectors which are capable of obtaining more information especially from HPLC and less urgently from GC instruments. At present, the mass spectrometer is the only detector for HPLC and GC capable of providing qualitative identifications of PAH. For this reason, matrix isolation fluorescence and infrared spectroscopy, low temperature Shpol'skii fluorescence spectroscopy, opto-electronic image detectors, and wavelength modulation and derivative spectroscopy are all being developed to provide more sophisticated information on HPLC and GC eluants.

ISSN:0007-8980    

DOI:10.1080/10408348208542751

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

An increasing number of researchers are recognizing the distinct advantages offered by molecular fluorescence spectroscopy as an analytical tool. This increase is evident from the large number of manuscripts and monographs published in this area. In the area of fluorescence instrumentation alone, the number of referenced articles in the biennial "Fundamental Reviews" ofAnalytical Chemistryincreased from 82 in 1976 to 156 in 1978. This widespread use of fluorescence analysis arises from its selectivity and sensitivity. The selectivity of fluorescence assay is derived from the dependence of the emission intensity both on the wavelength of the exciting radiation and on the wavelength of detection for the emitted radiation. Thus, it is often possible to find optimal spectral regions where the effects of background or interfering fluorescence are minimized. Moreover, the use of phosphorescence spectra and exploitation of differences in lifetimes and polarization can provide even greater selectivity. The sensitivity advantage of fluorescence arises from the direct detection of the emitted photons to give an emission signal. This is in contrast to absorption spectroscopy, in which a small difference between two large signals is measured. Consequently, with the use of state-of-the-art detectors, the sensitivity of fluorescence methods will often surpass the sensitivity of similar absorption methods by three orders of magnitude.

ISSN:0007-8980    

DOI:10.1080/10408348208542752

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor