Selective detectors, chromatography

Identification of stmctures of toxic chemicals in environmental samples requires to use modern analytical methods, such as gas chromatography (GC) with element selective detectors (NPD, FPD, AED), capillary electrophoresis (CE) for screening purposes, gas chromatography/mass-spectrometry (GC/MS), gas chromatography / Fourier transform infra red spectrometry (GC/FTIR), nucleai magnetic resonance (NMR), etc. 

D F S Natusch and T M Thorpe, Element selective detectors in gas chromatography, Anal. Chem., 1973,45, 1184A... 

MS detection does not necessarily require as highly resolved GC separations as in the case of selective detectors because the likelihood of an overlapping mass spectral peak among pesticides with the same retention time is less than the likelihood of an overlapping peak from the same element. Unfortunately, this advantage cannot always be optimized because SIM and current gas chromatography/tandem mass spectrometry (GC/MS/MS) methods, it is difficult to devise sequential SIM or MS/MS retention time windows to achieve fast GC separations for approximately > 50 analytes in a single method. 

Gas chromatography/mass spectrometry (GC/MS) Gas chromatograph equipped with a split/splitless injector, autosampler, DB-5 MS fused-silica column, 15 m x 0.25-mm i.d., 0.25-qm film thickness and mass-selective detector... 

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. 

Evaporative LC-FTIR is rapidly gaining industrial acceptance as a useful tool in low-MW additive analysis. HPLC has also been coupled with various element-selective detectors. There is significant demand for speciation information for many elements, and the separation ability of chromatography coupled to ICP-MS offers the analyst a versatile tool for such studies. It is apparent that ICP-MS is increasingly being employed for chromatographic detection. Several modes of GC, SFC, LC and CE have been hyphenated with ICP-MS for improved detection limits compared to other traditional methods of detection such as UV-VIS spectroscopy. Inorganic speciation deserves more attention. 

Marano RS, Levine SP, Harvey TM. 1978. Trace determination of subnanogram amounts of acrylonitrile in complex matrices by gas chromatography with a nitrogen-selective detector. Anal Chem 50 1948-1950. 

Gas chromatography is one of the most powerful analytical techniques available for chemical analysis. Commercially available chemiluminescence detectors for GC include the FPD, the SCD, the thermal energy analysis (TEA) detector, and nitrogen-selective detectors. Highly sensitive detectors based on chemiluminescent reactions with F2 and active nitrogen also have been developed. 

Lehane, D.P. et al. 1976. Therapeutic drug monitoring Measurements of antiepileptic and barbiturate drug levels in blood by gas chromatography with nitrogen-selective detector. Ann Clin Lab Sci. 6 404. 

To examine variation in the quality of methyl ketones expressed by females and newly-emerged males, we determined the number of unique methyl ketones expressed by individual snakes and compared the relative concentrations of individual methyl ketones comprising the overall pheromone profiles for the two groups. The methyl ketones present in the pheromone extracts were identified by gas chromatography / mass spectrometry (Hewlett Packard 5890 Series II gas chromatograph coupled with a Hewlett Packard 5971 Series mass selective detector— see LeMaster and Mason 2003 for full description of the GC/MS platform and methods). 

Calverly and Denny [199] have described a rapid and sensitive procedure for the determination of residue levels of three uracil herbicides in soils. After addition of calcium hydroxide and Celite to the soil the herbicides are eluted from columns with water. After acidification of the eluate and partition into chloroform these herbicides are determined by gas chromatography using a nitrogen-selective detector. Recoveries from a range of soil types are better than 80%, with a sensitivity limit of 20pg kgy1. 

GC = gas chromatography GPC = gel permeation chromatography ECD = electron capture detector MS = mass spectrometry MSD = mass selective detector SFE = supercritical fluid extraction TLC = thin layer chromatography... 

Stan HJ, Heil S. 1991. Two-dimensional capillary gas chromatography with three selective detectors as a valuable tool in residue analysis State-of-the-art. Fresenius Journal of Analytical Chemistry 339(1) 34-39. 

In the domain of gas chromatography the electron capture detector (ECD) enjoys the reputation of being one of the most sensitive as well as selective detectors. However, this valuable detector needs to be handled with a lot of skill and expertise so as to achieve wonderful and dependable results. 

M. Dressier, Selective Gas Chromatography Detectors, Elsevier, Amsterdam, 1986. 

Test methods that analyze individual compounds (e.g., benzene-toluene-ethylbenzene-xylene mixtures and PAHs) are generally applied to detect the presence of an additive or to provide concentration data needed to estimate environmental and health risks that are associated with individual compounds. Common constituent measurement techniques include gas chromatography with second-column confirmation, gas chromatography with multiple selective detectors, and gas chromatography with mass spectrometry detection (GC/MS) (EPA 8240). 

LA. Buryakov, Yu. N. Kolomiets and V.B. Louppou, Ion non-linear drift spectrometer (INLDS) — a selective detector for high-speed gas chromatography. International Journal for Ion Mobility Spectrometry 4(1) (2001) 13-15. 

Pesticides (14, 85), polychlorinated biphenyls (86, 87) and herbicides (88) are usually separated by this technique also. In analytic work, however, the detection sensitivity of the selective detectors used in gas chromatography could not be achieved (59). Nevertheless, sUch substances can be separated by liquid chromatography with no attendant decomposition problems and no derivatization, making the procedure significantly simpler. i... 

High-performance liquid chromatography (HPLC) allowed resolving these problems, and the possibility to apply almost every kind of very sensitive, and sometimes selective, detector greatly improved its held of nse. 

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