Time-array detection data collection

There has been a considerable decline in the number of papers which deal with the details of techniques of measurement of fluorescence decay. This is no doubt due to the fact that the alternative methods are now essentially well established. Nevertheless a microcomputerized ultrahigh speed transient digitizer and luminescence lifeline instrument has been described . A very useful multiplexed array fluorometer allows simultaneous fluorescence decay at different emission wavelength using single photon timing array detection . Data collection rates could approach that for a repetitive laser pulse system and the technique could be usefully applied to HPLC or microscopy. The power of this equipment has been exemplified by studies on aminotetraphenylporphyrins at emission wavelengths up to 680 nm. The use and performance of the delta function convolution method for the estimation of fluorescence decay parameters has been... 

Time-Slice Vs.Time-Array Detection. Holland et al. have referred to this method of data collection as time-slice recordinj. It is shown schematically in... 

Schematically, two main systems can be used to collect 3D fluorescence data (time, wavelength, number of photons, see fig. 1). In a first type of system, light is directed into a monochromator connected to a photomultiplier tube and then to a fast oscilloscope (PM detection). The experimentalist thus collects luminescence decays at various wavelengths. This system is known to be very efficient for luminescence decay acquisition but is very time-consuming for the acquisition of emission spectra. In the second type of system, light is directed to a diode array detector (or CCD camera) and a subsequent electronic detection device (diode detection). The experimentalist collects emission spectra at various delay times (time zero for the pulse entering in the sample). This system is very efficient for emission data acquisition but, on the other hand, time-consuming for luminescence decay acquisitions. From this very schematic description, it appears that a system combining the two types of detections would be the optimum.

Another example of the use of optical multichannel detection is the picosecond spectroscopic study of acridine, s-tetrazine, and rhodamine B by Barbara et. al.(26) In this type of study, a sample containing the compound of interest is placed in the path of an A,6-ps FWHM laser pulse. The laser pulse is focused onto the sample cell, and the emitted light is collected and directed, by an assembly of lenses, into a streak camera which is capable of time-resolving the emission. Processing and analysis of the streak camera data are accomplished by means of an assembly consisting of a two-dimensional photodiode array... 

Particularly, in a residue analysis, identification of detected analytes is required to confirm a result. For nitrofurans analysis, there are a few confirmatory methods reported, including the use of the photodiode-array system and MS detection. The use of a photodiode array detector coupled to HPLC (HPLC-DAD) offers advantages that the target peak can be identified by its retention time and absorption spectrum. In this case, the continuous spectral data generated during the analysis are collected to check for interfering substances by comparing the spectra of samples with those of the standards. However, the specificity and the limit of detection are not sufficient to determine or identify... 

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