Electron-capture detector performance

EC = electrical conductivity detector ECD = electron capture detector FPD = flame photometric detector GC = gas chromatography HPLC = high performance liquid chromatography NPD = nitrogen phosphorus detector TID = thermionic detector UV = ultraviolet spectroscopy... 

GC = gas chromatography ECD = electron capture detector EIA = enzyme-immunoassay GPC = gel permeation chromatography HPLC = high-performance liquid chromatography ITMS = ion trap mass spectrometer LSE = liquid solid extraction MS = mass spectrometry RSD = relative standard deviation SPE = solid phase extraction... 

Gas chromatograph equipped with an electron capture detector High-performance liquid chromatograph... 

Detectors are composed of a sensor and associated electronics. Design and performance of any detector depends heavily on the column and chromatographic system with which it is associated. Because of the complexity of many mixtures analysed and the limitation in regard to resolution, despite the use of high-resolution capillary columns and multicolumn systems, specific detectors are frequently necessary to gain selectivity and simplify the separation system. Many detectors have been developed with sensitivities toward specific elements or certain functional groups in molecules. Those detectors that exhibit the highest sensitivity are often very specific in response, e.g. the electron capture detector in GC or the fluorescence detector in LC. Because... 

The CGC analysis of the volatile degradation products were performed using a Perkin-Elmer Sigma 2000 capillary gas chromatograph. The column used was either a fused silica 0.25 micron, bonded methyl silicone (10 m, 0.25 mm I.D.) or a methyl/5% phenyl silicone (15 m 0.25 mm I.D.) bonded phase. The carrier gas was helium and the capillary column head pressure was maintained at 20 psi. The make-up gas for the pulsed electron capture detector (ECD) was 95% Ar/5% methane supplied at a flow rate of 60 ml/min. 

Elimination of wet chemical sample preparation enables a complete analysis to be performed and data to be quickly analyzed. The detection limits are in the low part-per-million range using mass spectrometric detection. Alternatively, detection of compounds can be achieved by all common gas chromatography detectors (flame ionization detector, electron capture detector and flame photometric detector), and detection limits are determined by the method of detection employed. 

ECO = electron capture detector ED = electrochemical detector FID st flame ionization detector GC = gas chromatography HECD = Hall s electrolytic conductivity detector HPLC = high performance liquid chromatography MEC = molecular emission cavity analysis MS - mass spectrometry HD = photo-ionization detector... 

Chromatographic Conditions. GC-ECD analyses were performed in an HP 5890 series II GC equipped with an electron capture detector and a split/splitless injector, operated by an HP Chemstation software. PCBs were separated on a 25 m length X 0.32 mm i.d., HP-1 column coated with a 0.17 pm film. The GC oven temperature program was as follows 90 °C hold 2 min, rate 20 °C/min to 170 °C, hold for 7.5 min, rate 3 °C/min, to final temperature 280 °C, and hold for 5 min. Nj was employed as carrier and makeup gas, with a column flow of 1.2 mL/min at 90 °C. Split flow was set at 50 mL/min. 

Validation Validation was defined in Section 3. It is the process of evaluating a method, an instrument or other piece of equipment, a standard material, etc. to determine whether it is appropriate for the work at hand and whether it will meet all expectations and needs for a given analysis. For example, an analyst may propose that a new gas chromatograph, one that has a new design of electron capture detector, be used for a certain pesticide analysis performed in the laboratory. A validation process would involve testing the new instrument (alongside the unit currently used in the procedure) with standards and samples used in the analysis to validate whether the new unit will perform up to the standards that have been set for the work. If it can be documented that the quality of the overall analysis by the new instrument meets expectations, then it can be brought "online."... 

ECD = electron capture detector GC = gas chromatography GFF = glass fiber filter(s) HPLC = high performance liquid chromatography MS = mass spectrometry NIOSH = National Institute of Occupational Safety and Health nitro reagent = A/-4-nitrobenzyl-A/-/ -propylamine UV = ultraviolet... 

The purpose of the carrier is to transport the sample through the column to the detector. The selection of the proper carrier gas is very important because it affects both column and detector performance. Unfortunately, the carrier gas that gives the optimum column performance is not always ideal for the particular detector. The detector that is employed usually dictates the carrier to be used. For instance, an electron capture detector operating in the pulsed mode requires an argon-methane mixture a thermal conductivity detector works best with hydrogen or helium. The most common carrier gases are listed in Table 6.1. 

Analysis of extracts was performed on a gas chromatograph (GC) (5880A, Hewlett-Packard) equipped with an electron-capture detector (ECD) and a 30-m fused silica capillary column with an outer diameter of 0.25 mm and a film thickness of 0.25 xm (Durabond DB-5, J W Scientific). The internal standard method developed by Dunnivant and Elzerman (15) was used, except that that only one internal standard was used (Aldrin) to minimize run time on the gas chromatograph. Daily working standards were composed of 80% Aroclor 1016 and 20% Aroclor 1254. This ratio was chosen because it matches the Aroclor distribution found in the sediments by Polansky (13). Quantification and collation of data were done on microcomputers with a spreadsheet program (SuperCalc 4, Computer Associates International). 

Various alkyl and aryltin compounds were determined in aquatic matrices, namely sediments, biota and water by means of gas chromatographic methods. In this work, comparisons of single or dual flame photometric detectors and electron capture detectors were reported (Tolosa et al., 1991). Sample preparations included acid digestion, extraction, formation of methyl derivatives and clean-up with alumina prior to gas chromatographic analysis. With the electron capture detector, cold on-column injection of organo-tin chlorides was studied. The conclusion was that a single or dual flame photometric detector equipped with a 600 nm interference filter yielded the best performance for determinations of tin species as methyl derivatives. Detection limits for the method using flame... 

The gas chromatograph is equipped with a 63Ni electron capture detector mounted in parallel with a flame ionisation detector and an auxiliary vent by the use of a column effluent splitter. The separation is performed on a 4.8mm od, 6m long stainless steel column packed with 16.5% silicone oil DC-550 on Chromosorb W AW DMCS. 

The analysis scheme implemented at the Cos Cob site used three sets of tools hand-held test kits, an on-site mobile laboratory equipped with gas chromatograph/ electron capture detector (GC/ECD) and X-ray fluorescence (XRF), and an off-site laboratory with rapid turnaround capabilities (<48 h for virtually all analyses). By implementing all of these tools at the same time, the project eliminated the need for multiple sampling events and allowed the team to perform additional real-time sampling, enabling the team to delineate the extent of potential hot spots quickly. 

Giachetti et al. [60] compared the performance of mass selective detector (MSD), electron capture detector (ECD) and nitrogen-phosphorus detector (NPD) of gas chromatography systems in the assay of six nonsteroidal antiinflammatory drugs in the plasma samples. As a practical test, six NSAIDs (mefenamic, flufenamic, meclofenamic and niflumic acids, diclofenac and clonixin) added to plasma samples were detected and quantified. The analyses were carried out after solvent extraction from an acidic medium and subsequent methylation. The linearity of response was tested for all the detection systems in the range of 1-25 ng/mL. Precision and accuracy were detected at 1, 5 and 10 ng/mL. The minimum quantifiable level for the six drugs was about 1 ng/mL with each of the three detection systems. 

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