The Experts below are selected from a list of 207 Experts worldwide ranked by ideXlab platform

George Crawford - One of the best experts on this subject based on the ideXlab platform.

  • trace residue analysis of the herbicide chlorsulfuron in soil by gas chromatography Electron Capture Detection
    Journal of Agricultural and Food Chemistry, 1990
    Co-Authors: Ijaz Ahmad, George Crawford
    Abstract:

    (...) The aqueous extract is washed with dichloromethane, acidified with hydrochloric acid, and extracted with dichloromethane. The organic extract is dried with anhydrous sodium sulfate and concentrated. The chlorsulfuron in the extract is derivatized with diazomethane to its monomethyl derivative. After Florisil cleanup, the monomethylchlorsulfuron in the sample is analyzed by capillary column gas chromatography-Electron Capture Detection. The recovery of chlorsulfuron from soil samples is greater than 80%. The experimental Detection limit of the method is 1 ng/g (1 ppb)

Locksley H Trenholm - One of the best experts on this subject based on the ideXlab platform.

  • analysis of trichothecene mycotoxins by gas chromatography with Electron Capture Detection
    Journal of Agricultural and Food Chemistry, 1994
    Co-Authors: Stephen M Croteau, Dan B Prelusky, Locksley H Trenholm
    Abstract:

    A sensitive gas chromatographic (GC) method for the quantitative analysis of 13 trichothecene mycotoxins in corn was developed. Derivatives sensitive to Electron Capture Detection (ECD) were formed using heptafluorobutyric anhydride in the presence of the acylation catalyst (dimethylamino)pyridine. Optimal reaction conditions were found to consist of reacting a sample for 20 min at 60 o C in a toluene-acetonitrile (8+2) reaction solvent. An aqueous wash with 5% (w/v) sodium bicarbonate effectively removed excess derivatizing reagent

Ijaz Ahmad - One of the best experts on this subject based on the ideXlab platform.

  • trace residue analysis of the herbicide chlorsulfuron in soil by gas chromatography Electron Capture Detection
    Journal of Agricultural and Food Chemistry, 1990
    Co-Authors: Ijaz Ahmad, George Crawford
    Abstract:

    (...) The aqueous extract is washed with dichloromethane, acidified with hydrochloric acid, and extracted with dichloromethane. The organic extract is dried with anhydrous sodium sulfate and concentrated. The chlorsulfuron in the extract is derivatized with diazomethane to its monomethyl derivative. After Florisil cleanup, the monomethylchlorsulfuron in the sample is analyzed by capillary column gas chromatography-Electron Capture Detection. The recovery of chlorsulfuron from soil samples is greater than 80%. The experimental Detection limit of the method is 1 ng/g (1 ppb)

Graham Nickless - One of the best experts on this subject based on the ideXlab platform.

  • Investigation of the use of oxygen doping of the Electron-Capture Detection for determination of atmospheric halocarbons
    Journal of Chromatography A, 1995
    Co-Authors: G.a. Sturrock, Peter Simmonds, Graham Nickless
    Abstract:

    Abstract The development of a GC-Electron-Capture Detection instrument to determine accurately certain important trace C 1 halocarbons in a single analytical procedure from ambient air is reported. The procedure utilizes preconcentration at room temperature on an efficient microtrap filled with a commercially available adsorbent, Carboxen, followed by direct thermal desorption in a single stage on to a high-resolution capillary column. Detection is achieved with dual Electron-Capture detectors in series; the second being oxygen doped to dramatically enhance the sensitivity of the detector towards those halocarbons (hydrofluorochlorocarbon 22, CH 3 Cl) which normally react feebly with thermal Electrons.

  • Gas chromatographic determination of volatile alkenes by on-column bromination and Electron-Capture Detection
    Journal of Chromatography A, 1995
    Co-Authors: D.p. Trigg, Peter Simmonds, Graham Nickless
    Abstract:

    Abstract A method is described for the GC-Electron-Capture Detection determination of ultra trace quantities of alkenes via on-column bromination reactions. Copper bromide coated onto a non-polar solid support, Gas Chrom Q (100–120 mesh) acted as the bromine source. At a temperature of 90–110°C, steel wool may be used to remove selectively up to 90% of the bromine bleed from the reactor. The conversion efficiency of an alkene to the dibrominated derivative is extremely high, up to 90% for ethene, propene, butene and pentene. The bromination of acetylene is also possible, but is not as efficient.

  • Determination of selenium by gas chromatography-Electron-Capture Detection using a rapid derivatization procedure
    Journal of Chromatography A, 1994
    Co-Authors: Abdusalam Elaseer, Graham Nickless
    Abstract:

    Abstract A rapid method of determination of selenium by gas chromatography with Electron-Capture Detection using 3-bromo-5-trifluoromethyl-1, 2-diaminobenzene as completing ligand was investigated. The temperature-dependent reaction was kinetically evaluated and at 100°C the time for the quantitative formation of piazselenol can be reduced to less than 5 min without any discrepancies in the quantitative determination of selenium. The method was applied to the determination of the organoselenium compounds evolved from incubated sediments. The compounds were separated and identified as dimethylselenide and dimethyldiselenide using GC-MS.

U.a.th. Brinkman - One of the best experts on this subject based on the ideXlab platform.

  • Determination of pentachlorophenol in rabbit and human liver using liquid chromatography and gas chromatography with Electron-Capture Detection
    Chemosphere, 2003
    Co-Authors: F.a. Maris, U.a.th. Brinkman, G.j. De Jong, Govert W. Somsen, C.e. Goewie, M.p.h. Van Den Broek
    Abstract:

    A method has been developed for the determination of ppb levels of pentachlorophenol (PCP) in liver by column liquid chromatography with on-line Electron-Capture Detection (LC-ECD). The technique is compared with gas chromatography-ECD (GC-ECD) for the analysis of rabbit and human livers. Good results were generally obtained for LC-ECD down to the low-ppb range; however, in some cases problems were observed when the sample is not dissolved in the LC eluent. LC-ECD can adequately be used as a confirmation method for GC-ECD.

  • Narrow-bore normal phase liquid chromatography with on-line Electron-Capture Detection
    Journal of Chromatography A, 2002
    Co-Authors: F.a. Maris, A. Van Der Vliet, R.b. Geerdink, U.a.th. Brinkman
    Abstract:

    Abstract Miniaturization of an on-line liquid chromatography—Electron-Capture Detection system has been achieved by using a suitable micropump, and a 40-μm I.D. fused-silica capillary as evaporation interface. The baseline stability is high and extra-column band broadening is comparable to that in conventional systems. The Detection limits for Electron-Capture-sensitive compounds are of the order of 1 pg, and calibration plots are linear over three orders of magnitude. The system has successfully been used for gradient elution with hexane—toluene mixtures on an amino-bonded phase.

  • Normal- and reversed-phase liquid chromatography with on-line Electron-Capture Detection
    Journal of Chromatography A, 2002
    Co-Authors: U.a.th. Brinkman, R.b. Geerdink
    Abstract:

    Abstract As a continuation of earlier work, the potential of high-performance liquid chromatography (LC) with on-line Electron-Capture Detection (ECD) has been further explored. For normal-phase LC it is demonstrated that the use of toluene instead of hexane as main mobile phase component has distinct advantages because it allows the rapid elution of even fairly polar model compounds. For reversed-phase systems, on-line LC-ECD is shown to be feasible if miniaturized equipment (1 mm I.D. columns; flow-rates of ca . 50 μl min′ -1 ) is used. Preliminary experiments indicate that reversed-phase LC combined with an on-line post-column extraction module may be an interesting alternative approach in reversed-phase LC-ECD.

  • Selection of mobile phases for reversed-phase liquid chromatography with on-line Electron-Capture Detection
    Journal of Chromatography A, 2001
    Co-Authors: F.a. Maris, R.b. Geerdink, U.a.th. Brinkman
    Abstract:

    Abstract Reversed-phase column liquid chromatography with on-line Electron-Capture Detection can conveniently be carried out if miniaturized equipment (1 mm I.D. columns) is used. As eluents, mixtures of methanol or dioxane and water are preferred to acetonitrile—water mixtures. With the former two modifiers, working at flow-rates of ca. 50 μl min −1 does not create any problems with mixtures containing between 0 and 50% water. At lower flow-rates, even pure water can be used as eluent. The addition to the mobile phase of small amounts of polar compounds such as phosphoric acid, can be tolerated. Examples of successful applications include the analysis of barbiturates, benzodiazepines, nitroaromatics, C1C2 halogenated aliphatic hydrocarbons, and chlorophenols.