Detectors sulfur selective

Because process mixtures are complex, specialized detectors may substitute for separation efficiency. One specialized detector is the array amperometric detector, which allows selective detection of electrochemically active compounds.23 Electrochemical array detectors are discussed in greater detail in Chapter 5. Many pharmaceutical compounds are chiral, so a detector capable of determining optical purity would be extremely useful in monitoring synthetic reactions. A double-beam circular dichroism detector using a laser as the source was used for the selective detection of chiral cobalt compounds.24 The double-beam, single-source construction reduces the limitations of flicker noise. Chemiluminescence of an ozonized mixture was used as the principle for a sulfur-selective detector used to analyze pesticides, proteins, and blood thiols from rat plasma.25 Chemiluminescence using bis (2,4, 6-trichlorophenyl) oxalate was used for the selective detection of catalytically reduced nitrated polycyclic aromatic hydrocarbons from diesel exhaust.26... 

Ryerson, T. B., Dunham, A. J., Barkley, R. M., and Sievers, R. E., Sulfur-selective detector for liquid chromatography based on sulfur monoxide-ozone chemiluminescence, Anal. Chem., 66, 2841, 1994. 

Table 4.9 Comparison of several commercially available sulfur-selective detectors...

Flame photometric detector (FPD) selective to compounds containing sulfur and phosphorus... 

It is obvious from the FTIR and NMR analyses of these extracts that in order to positively identify organosulfur structures we need an analytical technique that is sulfur selective. That is, a technique that responds to sulfur uniquely. One such technique, applicable to the problem in hand, is GLC-FID/FPD where the flame photometric detector is set in the sulfur selective mode. 

S. Gluck, Performance of the model 700A Hall electrolytic conductivity detector as a sulfur selective detector., J. Chromatogr. Sci., 20 103-108 (1982). 

S.E. Eckert-Tilotta, S.B. Hawthorne and D.J. Miller, Comparison of commercially available atomic emission and chemiluminescence detectors for sulfur-selective gas chromatographic detection, J. Chromatogr., 591, 313-323 (1992). 

Any sulfur-selective detector may be used e.g., electrolytic conductivity, flame photometric, or sulfur chemiluminescence. The detector must be capable of detecting less than 0.1 ppm v/v of carbonyl sulfide with a signal-to-noise ratio of 10 1. 

Volatile sulfur compounds. Volatile sulfur compound are best determined in the headspaces using a sulfur selective detector. Different alternatives, based on direct headspace of headspace-SPME, have been developed (Rauhut et al. 1998 Mestres et al. 2000 Lopez et al. 2007). 

Hutte, R.S. and Ray, J.D. Sulfur-selective detectors. In Detector for Capillary Chromatography (eds. H.H. Hill, D.G. McMinn). New York John Wiley Sons, pp. 193-218, 1992. 

Gas chromatography with either sulfur chemiluminescence detection or atomic emission detection has been used for sulfur-selective detection. Selective sulfur and nitrogen gas chromatographic detectors, exemplified by the flame photometric detector (FPD) and the nitrogen-phosphorus detector (NPD), have been available for many years. However, these detectors have limited selectivity for the element over carbon, exhibit nonuniform response, and have other problems that limit their usefulness. 

Atomic emission detectors (AEM) in the carbon- and sulfur-selective modes have been used for the analysis of thiaarenes (references in Herod 1998 Mossner and Wise 1999), and to determine the contents of benzothiophene, dibenzothiophene, naphthothiophenes, phenan-thro[4,5-focd]thiophene, and benzo[fr]naphtho[2,l-d]thiophene in NIST samples of coal tar, crude oil, and shale oil (Schmid and Andersson 1997). The sulfur-selective detector has also proved valuable for the analysis of sulfones in environmental samples 0anak et al. 1998). 

Identified in roasted coffee by Sullivan et al. (1959), Heins et al. (1966), and Stoffelsma et al. (1968). Merritt et al. (1970) characterized it in roasted but not in green coffee. It is present in the headspace of roasted coffee (Cros et al., 1980 Wang et al., 1983 ), in the headspace of a brew (Shimoda and Shibamoto, 1990a) where it represents 0.67% (GC). Silwar et al. (1986) found concentrations of 0.01 ppm in arabicas and 0.10-0.12 in robustas after simultaneous distillation/extraction, capillary GC using simultaneously flame ionization or flame photometric (for sulfur-selective analysis) detectors (FID/ FPD). With a similar detection method in the GC analysis of the headspace compounds, Guyot and Vincent (1990) found 0.04-0.05 ppm in a roasted healthy arabica and 0.3-0.4 in the stinking quality (see Q.4). Procida et al. (1997) identified dimethyl disulfide in a roasted arabica but in none of the green coffees examined, contrary to their result for dimethyl sulfide (Q.ll). 

Identified by Tressl et al. (1981) after distillation-extraction, separation by chromatography, preparative GC, then capillary GC with either flame ionization or flame photometric (for sulfur-selective analysis) detector. Silwar et al. (1986) after simultaneous distillation-extraction used the two detectors simultaneously for quantifying the sulfur compounds (see Q.14). They found less than 0.01 ppm of this dithiolane in arabicas as well as in robustas. 

Other even more sjjccific detectors can also be coupled to GCxGC. Atomic emission detectors (AEDs), and more element-selective detectors, such as sulfur compound detectors (sulfur chemiluminescence detector, or SCD), have been reported in the oil characterization area [84,85]. In these detectors, the combustion of sulfur compounds by an energetic induced plasma produces sulfur oxides that further react to and produce light at a specific wavelength that... 

Besides the universal FID-detector, the selective electron capture (ECD), nitrogen-selective thermionic (NPD) and flame photometric (FPD) detectors have been used for the measurement of PAH, and nitrogen or sulfur containing heterocyclic analogs respectively (Wakeham (26), Willey et al. (29)). 

Universal sulfur-selective detectors for GC or supercritical fluid chromatography (SFC), that incorporate a cool hydrogen-rich flame or closed hydrogen/ air burner have been developed and are now commercially available. Combustion products are transferred via a connecting line to a low-pressure reaction cell, where they are mixed with ozone. Although sulfur monoxide is believed to be the common intermediate that reacts with ozone to form the excited sulfur dioxide emitter, it is not necessarily the product of the first conversion step, which has caused debate between instrument manufacturers. One proposed mechanism proceeds as shown in reaction [VI] and it was suggested that the reduced sulfur species could be H2S ... 

Element selective detectors Element selective detectors applicable in pesticide residue analysis include electron capture detector (ECD), electrolytic conductivity detector (ELCD), halogen-specific detector (XSD), nitrogen phosphorus detector (NPD), flame photometric detector (FPD), pulsed flame photometric detector (PEPD), sulfur chemiluminescence detector (SCD), and atomic emission detector (AED). To cover a wider range of pesticide residues, a halogen-selective detector (ECD, ELCD, XSD) in conjvmction with a phosphorus- (NPD, FPD), nitrogen- (NPD), and/or sulfur-selective detector (FPD, SCD) is commonly used. A practical approach is to spht the column flow to two detectors that reduces the number of injections however, the reduced amoimt of analyte that reaches the detector must be considered. 

Sulfur Chemiluminescence Detector. Another sulfur selective detector based on photometric sensing of a chemiluminescent reaction has become commercially available (Sievers Research, Inc., Boulder, CO). Similar to the FPD, the detection scheme of the SCD incorporates combustion of the GC column effluent in a hydrogen rich flame. However, the sulfur species detected is an excited state of sulfur dioxide (SO2 ), not... 

Paradoxically, the gas-density detector, which can supply the molecular mass of an unknown, can be considered to be a selective detector in gas chromatography (58). This comment effectively illustrates the dearth of convenient selective detectors. At best such detectors help to identify compounds that contain halogen atoms (electron-capture or thermoionic detectors), sulfur, nitrogen, or phosphorus (flame-photometric or thermoionic detectors). Physiological detectors have also been used in certain rare cases (insects that react to sexual pheromones, for example, or the chemist s nose, a dangerous and hazardous application). 

Because one of the end groups in most of the PMMA examined in this study should have a sulfur atom or a cyano group, the Py-GC system is equipped with a simultaneous multidetection system. A FID was always used in conjunction with a sulfur-selective flame photometric detector (FPD) or a nitrogen-phosphorus detector (NPD). 

R. Frito, B. Quimby, A comparison of sulfur selective detectors for low level analysis in gaseous streams—application, Agilent Technologies 5988-2426EN, 2001. 

D5623, Sulfur compounds by GC sulfur selective detector X X ... 

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