GC-electron capture detection

GC/electron capture detection (ECD) is also used to measure DBFs. In particular, EFA Method 552.2 and 552.3 are commonly used to measure haloacetic acids in drinking water [156, 157]. ECD is very sensitive toward halogenated compounds and allows low-level detection for HAAs (0.012-0.17 pg/L detection limits for EFA Method 552.3). 

PDMS-fibers were analyzed by GC-electron capture detection using an HP 5890... 

PDMS-fibers were analyzed by GC -electron capture detection using a HP 5890 series II GC. PDMS-DVB fibers were analyzed by GC/MS-MS irsing aVarian 3800 GC with ion trap (Varian Saturn 2000). 

Kirkbride (1987) described the estimation of diazinon in human omental tissue (fatty tissue) after a fatal poisoning. In this method, the tissue was pulverized and extracted with acetone. After extract concentration and purification by sweep co-distillation and Florisil fractionation, diazinon was measured by gas chromatography (GC) with nitrogen-phosphorus detection (NPD). After another fatal diazinon poisoning, diazinon was quantified by GC/electron capture detection (ECD) and GC/flame ionization detection (FID) by Poklis et al. (1980). The diazinon in human adipose, bile, blood, brain, stomach contents, kidney, and liver was recovered by macerating the sample with acetonitrile followed by the addition of aqueous sodium sulfate and extraction into hexane. Following an adsorption chromatography clean-up, the sample was analyzed. 

The analytical method used, which involved sample extraction followed by cleanup and determination by gas chromatography (GC)/electron capture detection (ECD), had a repeatability standard deviation of 1.3 qg/kg therefore a contribution of at least -2.6 y/g/kg to the uncertainty (k=2) of the certified value must be expected when using this method to assess homogeneity. Such a value will make the major contribution to the total uncertainty (U) of the certified value, especially where the latter is based on high-accuracy IDMS measurements, which have an expanded uncertainty of only -0.7 y/g/kg (Table 2). 

The external factors influencing nimodipine concentrations during intravenous administration were studied using GC-electron-capture detection [18]. Nimodipine was extracted from plasma and analyzed using a column (1.8 m x 2 mm) packed with 3% of OV-17 on gas-Chrom Q (50-100 mesh). The column was operated at 255°C with nitrogen as the carrier gas (flow rate of 25 mL/min), and 63 Ni ECD. The calibration graph was linear for upto 1000 ng/mL, and the limit of detection was 0.5 ng/mL. 

Finally, formation of 0-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine (PFBOA) derivatives and analysis by GC-Mass Spectrometry (GC-MS) and GC-Electron-Capture Detection (GC-ECD) appears to be a promising technique, de Revel and Bertrand (42, 43) used PFBOA derivatization to analyze a number of saturated and unsaturated aldehydes in wines, however, high concentrations of acetaldehyde made accurate quantitation of the other aldehydes present in lower concentrations difficult, depending on the wine matrix the aldehydes were not always well separated from other chromatographic peaks pH conditions for the derivatization were not specified and removal of excess PFBOA by acidification caused the partial loss of some aldehydes. In addition, no specific information regarding derivatization efficiency and recovery, or absolute limits of detection and quantitation were reported by these authors. 

As stated above, most users of the headspace technique make no distinction between dynamic HS and PT. In one of the few publications that distinguished and compared these two HS modes, dynamic HS and PT were assessed as steps preceding high-resolution GC-electron capture detection for the determination of nitrous oxide in sea water. The process was found to exhibit a first-order kinetics in both cases and the matrix to exert a significant effect that was proportional to the nitrous oxide concentration in bidistilled water, as well as in synthetic and natural sea water. As expected, PT provided better extraction recovery, sensitivity and limits of detection — which fell in the pico-mole-per-millilitre range [46]. 

The OP parathion and its active metabolite paraoxon were simultaneously determined in plasma and tissues by Abbas and Hayton. Their method involved a simple liquid-liquid extraction with isooctane with subsequent GC-electron capture detection and yielded recoveries from 79-110% for tissues and 91-100% for plasma. Fenitrothion, another OP, was detected in blood samples and tissues by Yoshida et al. using a GC-FPD method. Kojima et al. reported a case of attempted suicide by ingestion of a fenitrothion emulsion fenitrothion and its metabolites were extracted from body fluids by an Extrelut column extraction method and subsequently detected by GC with either FID or FPD. Data were confirmed using GC-MS. No validation data were given. 

The superiority of microwave extraction compared to traditional extraction methods for the determination of polychlorinated biphenyl compounds in indoor air samples was also shown. Again a decrease in the extraction time was highlighted the microwave procedure needed only 10 min and, followed by GC-electron capture detection, was claimed as a valuable alternative to the Soxhlet method for the extraction of six noncoplanar PCBs associated with fly ashes. 

Jayasinghe, L. Y., Marriott, P. J., Carpener, P. D., and Nichols, P. D., SFE and GC electron capture detection method for sterol analysis of environmental water samples. Anal. Commun., 35, 265-268,... 

Finally, GC detection of the manufacturing impurities of cocaine can be enhanced by chemical derivatization via the use of an electron-capture detector. In this method, unadulterated cocaine hydrochloride samples were deriva-tized directly in acetonitrile with heptafluorobutyric anhydride (HFBA) the derivatives of the manufacturing impurities were extracted into isooctane. Then the isolated derivatives were subjected to GC-electron capture detection analysis.This methodology is especially suitable for sample comparison analysis. 

GC-electron capture detection (compared to FID) SPE-UPLC-ESI-triple quad MS/MS Immunoassay GC-MS... 

The special problems for vaUdation presented by chiral separations can be even more burdensome for gc because most methods of detection (eg, flame ionization detection or electron capture detection) in gc destroy the sample. Even when nondestmctive detection (eg, thermal conductivity) is used, individual peak collection is generally more difficult than in Ic or tic. Thus, off-line chiroptical analysis is not usually an option. Eortunately, gc can be readily coupled to a mass spectrometer and is routinely used to vaUdate a chiral separation. 

J. Staniewski, H. G. Janssen, J. A. Rijks and C. A. Cramers, Inti oduction of large volumes of methylene cWoi ide in capillaiy GC with electron capture detection , in... 

The first bioanalytical application of LC-GC was presented by Grob et al. (119). These authors proposed this coupled system for the determination of diethylstilbe-strol in urine as a replacement for GC-MS. After hydrolysis, clean-up by solid-phase extraction and derivatization by pentafluorobenzyl bromide, the extract was separated with normal-phase LC by using cyclohexane/1 % tetrahydrofuran (THE) at a flow-rate of 260 p.l/min as the mobile phase. The result of LC-UV analysis of a urine sample and GC with electron-capture detection (ECD) of the LC fraction are shown in Ligures 11.8(a) and (b), respectively. The practical detection limits varied between about 0.1 and 0.3 ppb, depending on the urine being analysed. By use of... 

In this core, concentrations of PCBs (determined as Aroclor 1254 and 1260, by high resolution gas chromatography, electron capture detection and high resolution gas chromatography-low resolution mass spectrometry) were <30 ng and those of total DDT (p,p DDT + p,p DDD + p,p DDE) <5 ng g Campesan et al. (21) in 11 sediment samples from Valle di Brenta, determined by GC-ECD the following mean concentrations (ng gd.w.) ... 

Several methods are available for the analysis of trichloroethylene in biological media. The method of choice depends on the nature of the sample matrix cost of analysis required precision, accuracy, and detection limit and turnaround time of the method. The main analytical method used to analyze for the presence of trichloroethylene and its metabolites, trichloroethanol and TCA, in biological samples is separation by gas chromatography (GC) combined with detection by mass spectrometry (MS) or electron capture detection (ECD). Trichloroethylene and/or its metabolites have been detected in exhaled air, blood, urine, breast milk, and tissues. Details on sample preparation, analytical method, and sensitivity and accuracy of selected methods are provided in Table 6-1. 

The presence of heteroatoms usually provides a convenient feature for improving selectivity by employing selective detection mechanisms. GC may then use flame photometric detection (FPD) for S and P atoms and to a certain extent for N, Se, Si etc. thermoselective detection (TSD) and nitrogen-phosphorus detection (NPD) for N and P atoms electron capture detection (ECD) for halogen atoms (E, Cl, Br, and 1) and for systems with conjugated double bonds and electron-drawing groups or atomic emission detection (AED) for many heteroatoms. 

Residue analytical chemistry has extended its scope in recent decades from the simple analysis of chlorinated, lipophilic, nonpolar, persistent insecticides - analyzed in the first Si02 fraction after the all-destroying sulfuric acid cleanup by a gas chro-matography/electron capture detection (GC/ECD) method that was sometimes too sensitive to provide linearity beyond the required final concentration - to the monitoring of polar, even ionic, hydrophilic pesticides with structures giving the chemist no useful feature other than the molecule itself, hopefully to be ionized and fragmented for MS or MS" detection. 

Analytical methods for parent chloroacetanilide herbicides in soil typically involve extraction of the soil with solvent, followed by solid-phase extraction (SPE), and analysis by gas chromatography/electron capture detection (GC/ECD) or gas chromatog-raphy/mass spectrometry (GC/MS). Analytical methods for parent chloroacetanilides in water are similarly based on extraction followed by GC with various detection techniques. Many of the water methods, such as the Environmental Protection Agency (EPA) official methods, are multi-residue methods that include other compound classes in addition to chloroacetanilides. While liquid-liquid partitioning was used initially to extract acetanilides from water samples, SPE using... 

Gas chromatograph injector liner [for gas chromatography/electron capture detection (GC/ECD)], cyclouniliner insert, Restek (cat. No. 20337)... 

Universal and selective detectors, linked to GC or LC systems, have remained the predominant choice of analysts for the past two decades for the determination of pesticide residues in food. Although the introduction of bench-top mass spectrometers has enabled analysts to produce more unequivocal residue data for most pesticides, in many laboratories the use of selective detection methods, such as flame photometric detection (FPD), electron capture detection (BCD) and alkali flame ionization detection (AFID) or nitrogen-phosphorus detection (NPD), continues. Many of the new technologies associated with the on-going development of instrumental methods are discussed. However, the main objective of this section is to describe modern techniques that have been demonstrated to be of use to the pesticide residue analyst. 

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