Pulsed discharge detector

Pulsatile drug delivery systems, 9 57-61 Pulsating heat pipes (PHP), 13 235-236 Pulse combustion heat sources, 9 104-105 Pulse cycles, 9 778 Pulsed baffle reactors, 15 709-710 Pulsed discharge detector (PDD) gas chromatography, 4 614 Pulsed dye lasers, 23 144 Pulsed electrochemical machining (PECM), 9 604-605... 

Forsyth, D.S., Taylor, J. Detection of organotin, organomercury, and organolead compounds with a pulsed discharge detector (PDD). Anal. Bioanal. Chem. 374, 344-347 (2002)... 

Detection systems for GC are chosen for their sensitivity and selectivity for a particular class of VOCs. Detectors for GC include FID, the BCD, the photoionization detector (PID), the pulsed discharge detector (PDD), and the reduction gas detector (RGD). A variety of mass spectrometers can also be interfaced with a GC for confirmation of molecular structure and quantitation. Singlewavelength ultraviolet-visible detectors (190 to 600 nm) and diode array detectors are used to detect carbonyls as their 2,4-dinitrophenylhydrazone derivatives. The absorption maxima for aliphatic carbonyls, aromatic carbonyls, and dicarbonyls are near 360 nm, 385 to 390 nm, and 415 to 430 nm, respectively. Formic, acetic, and pyruvic acid are detected by ion conductivity. 

The pulsed discharge detector (PDD) is a universal and highly sensitive nonra-dioactive and non-destructive detector, also known as a helium photoionization detector. It is based on the principle of the photoionization by radiation... 

Figure 2.149 Pulsed discharge detector (PDD) in cutaway view (Thermo Scientific).

The pulsed helium discharge detector [7,8] is an extension of the helium detector, a diagram of which is shown in figure 11. 

The Pulsed Hehum Discharge Detector Courtesy of Valeo Instruments Company Inc. 

The Separation of Some Aromatic Hydrocarbons Monitored by the Pulsed Helium Discharge Detector... 

The pulsed discharge electron capture detector is an extension of the previously discussed pulsed discharge helium ionization detector, a... 

The sensor consists of two sections the upper section where the discharge takes place has a small diameter and the lower section where the column eluent is sensed and the electron capturing occurs has a wider diameter. As with the pulsed discharge helium ionization detector, the potential across the discharge electrodes is pulsed at about 3 kHz with a discharge pulse width of about 45 psec for... 

The Separation of Some Pesticides Monitored by the Valeo Pulsed Discharge Electron Capture Detector Courtesy of Valeo Instmments Company Inc. 

The Simple or Macro Argon Detector Sensor The Micro Argon Detector The Triode Detector The Thermal Argon Detector The Helium Detector The Pulsed Helium Discharge Detector The Electron Capture Detector The Pulsed Discharge Electron Capture Detector References Chapter 7... 

Fig.l The discharge ionization detector (courtesy of GOW-M AC Instruments) and the pulsed helium discharge detector (courtesy of Valeo Instruments). 

Wentworth has been a member of the American Chemical Society, the American Solar Energy Society, and Alpha Chi Sigma. He has published over 125 papers, written three textbooks, and received numerous patents. One of the publications from his doctoral dissertation was selected as a pioneer paper in analytical chemistry. His papers on the chemical applications of nonlinear least squares became Citation Index Classics. His patent for pulse discharge ionization detectors was selected as one of the 100 most significant inventions of 1997. He retired after four decades of teaching and research, having about forty graduate students, half of whom received doctorates. The Robert A. Welch Foundation supported his efforts every year. 

The ECD used to establish the kinetic model was custom-built. Affordable commercial ECD and negative-ion gas chromatograph chemical ionization mass spectrometers are now available. Thus in order for an investigator to use these techniques, it is simply a matter of calibrating the instrument by reproducing the experimental results to verify that no artifacts result from the equipment. The major work described in this book was conducted with the radioactive ECD. The mechanisms for the pulsed discharge electron capture detector are the same as with the radioactive ECD that is now commercially available [4]. We have used commercial detectors and a quadrupole mass spectrometer with a home-made data collection system to determine electron affinities and to study the complexes of negative ions [5-9]. 

FIGURE 3.10 Schematic diagrams of (a) conventional electron capture detector (BCD) (b) pulse discharge BCD. 

Chlorine Sensitive Pulsed Discharge Emission detector. 186... 

Constant current ECD is the most common mode of operation but fixed frequency is gaining acceptance. The thermal electron concentration in the detector cell is measured discontinuously by a pulsed voltage. A pulsed discharge ECD a nonradioactive source is more sensitive than the radioactive source for most compounds, covers a wide dynamic response range similar to the radioactive source. Cell volumes are typically 480 jA to 1.5 ml with 150 /tl for the micro ECD at a data acquisition frequency of 50 Hz. 

It is based upon molecular emission from KrCl. Low concentrations of krypton in helium (0.1 to 0.4%) are sufficient to react with chlorinated compounds in the pulsed discharge emission detector to produce an excited state of KrCl that emits in a fairly narrow molecular band at 221 to 222 nm. Spectrometers with conventional quartz optics are sufficient to detect this emission. 

Abbreviations GC, Gas Chromatography IRMS, Isotope Ratio Mass Spectrometry ECD, Electron Capture Detector FID, Flame Ionization Detector TCD, Thermal Conductivity Detector MS, Mass Spectrometry PDHID, Pulsed-Discharge Helium Ionization Detector mol. sieve, Molecular Sieve HP, Hewlett-Packard PE, Perkin-Elmer. 

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