Investigations of Electron Capture Gas Chromatography for the Analysis of Multiple Chlorinated Pesticide Residues in Vegetables

1964 ◽  
Vol 47 (2) ◽  
pp. 326-342
Author(s):  
Jerry Burke ◽  
Laura Giuffrida
Keyword(s):  
Electron Capture ◽  
Gas Chromatograph ◽  
Green Beans ◽  
Chlorinated Pesticides ◽  
Reagent Blank ◽  
Efficient Operation ◽  
Average Recovery ◽  
Relative Retention ◽  
Automatic Integration ◽  
Peak Areas

Abstract Conditions have been experimentally worked out for most efficient operation of the electron capture gas chromatograph, with the objective of routinely determining 0.01 ppm of residues of chlorinated pesticides with GLC characteristics like heptachlor epoxide. These conditions are as follows: Column 6' long by 4 mm i.d., packed with 10% DC 200 (12,500 est) on 80/90 mesh Anakrom ABS, conditioned 1—5 days at 250°C; 200°C column and detector temperature; 120 ml/min. flow N2. Conditioning of the column by chromatographing cleaned up crop extracts through it improves results with certain pesticides. Relative retention times are tabulated for 65 compounds. Sample cleanup is essential for consistently accurate results; the Mills-Onley-Gaither method was used in our work. To insure a zero reagent blank, solvents must be distilled, all glassware rinsed with solvent, blender and funnel carefully cleaned, and no polyethylene containers used to store solvents. Quantitative analysis is made by comparing peak areas of sample and standard, preferably by automatic integration. Experimental work on crop samples was done with corn, spinach, carrots, green beans, potatoes, broccoli, peas, lettuce, radishes, green onions, kale, and cabbage. Over-all average recovery was 84% for seven common pesticides added to 100 g samples of broccoli at 0.001-0.1 ppm.

Program for Computation of Response Data from Five Different Gas Chromatograph Detectors Operating Simultaneously

1978 ◽  
Vol 61 (1) ◽  
pp. 18-25
Author(s):  
Harry A Mcleod ◽  
David Lewis
Keyword(s):  
Gas Chromatograph ◽  
Internal Standards ◽  
Baseline Drift ◽  
Response Data ◽  
Flame Ionization ◽  
Relative Retention ◽  
Data Points ◽  
Peak Areas ◽  
Smoothing Procedure ◽  
Spurious Signals

Abstract A novel digital computer program for evaluating data from a gas chromatograph with 5 different detectors—electron capture, flame ionization, nitrogen, phosphorus, and sulfur—operating simultaneously is described. Detector signals are recorded on a 9-channel incremental tape, and then processed off-line by using a NOVA 8K computer system. Spurious signals from each detector are minimized by applying a simplified least squares smoothing procedure to the raw data points. Peak detection logic operating parameters may be varied for each detector. Relative retention times are calculated for 2 internal standards as references and peak areas are corrected for baseline drift. Operator interaction is maximal and several different data reporting formats are used to tabulate the raw and processed data.

Gas Chromatography with Microcoulometric Detection for Pesticide Residue Analysis

1964 ◽  
Vol 47 (5) ◽  
pp. 845-859
Author(s):  
Jerry Burke ◽  
Wendell Holswade
Keyword(s):  
Detection System ◽  
Residue Analysis ◽  
Detection Technique ◽  
General Level ◽  
Chlorinated Pesticides ◽  
Efficient Operation ◽  
Column Temperature ◽  
Relative Retention ◽  
Minimum Number ◽  
Multiple Detection

Abstract Conditions are given for the most efficient operation of the microcoulometric gas chromatograph as a multiple detection technique for residues of chlorinated pesticides. Conditions are as follows: Column, aluminum, 6’ long by 4.5 mm i.d., packed with 10% DC 200 silicone fluid (12,500 est) on 80/90 mesh Anakrom ABS (conditioned 1—5 days at 250°C), 210°C column temperature, and 120 ml/min. N2 flow. Chromatography of certain pesticides is improved by injection of cleaned up crop extracts. Columns with a minimum number of bends are superior to coiled columns. Chromatography is not improved by using glass columns. Relative retention times and instrument sensitivity are tabulated for 87 chlorinated and 26 thio pesticide chemicals. Theoretical chloride recoveries are given for 14 compounds and sulfur recoveries for 3 compounds. Theoretical recoveries indicate that the MCGC system is linear for a particular pesticide when it is present above some minimum quantity. Sample cleanup is essential for consistently accurate and reproducible results. The general level of "maximum sensitivity" of this multiple detection technique is approximately 0.01 ppm. The specificity of the detection system (for CI-, Br-, I- or sulfur) is the instrument's greatest virtue.

Gas chromatography with ballistic heating and ultrafast cooling of column

2008 ◽  
Vol 62 (2) ◽  
Author(s):  
Žofia Krkošová ◽  
Róbert Kubinec ◽  
Helena Jurdáková ◽  
Jaroslav Blaško ◽  
Ivan Ostrovský ◽  
...  
Keyword(s):  
Gas Chromatography ◽  
Capillary Column ◽  
Gas Chromatograph ◽  
Good Separation ◽  
Relative Retention ◽  
External Cooling ◽  
Peak Areas ◽  
Fast Cooling ◽  
Cooling Module ◽  
Ultrafast Cooling

AbstractAn overview of the existing methods for minimization of the analysis time in gas chromatography (GC) is presented and a new system for fast temperature programming and very fast cooling down is evaluated. In this study, a system of coaxial tubes, a heating/cooling module (HC-M), was developed and studied with a capillary column placed inside the HC-M. The module itself was heated by a GC oven and cooled down by an external cooling medium. The HC-M was heated at rates of up to 330 °C min−1 and cooled at the rate of 6000 °C min−1. The GC system was prepared for the next run within a few seconds. The HC-M permits good separation reproducibility, comparable with that of a conventional GC, expressed in terms of relative retention times and peak areas of analytes reproducibilities. The HC-M can be used within any commercial gas chromatograph.

Programmed Temperature Gas Chromatography (PTGC) and Microcoulometric Detection of Chlorinated Insecticides

1963 ◽  
Vol 46 (2) ◽  
pp. 198-204
Author(s):  
Jerry Burke
Keyword(s):  
Gas Chromatography ◽  
Detection System ◽  
Operating Parameters ◽  
Gas Chromatograph ◽  
Relative Retention ◽  
Wide Range ◽  
Isothermal Gas

Abstract Commercial models of a programmed temperature gas chromatograph and microcoulometric detection system were combined to study programmed temperature gas chromatography (PTGC) of chlorinated insecticides. PTGC permitted the analysis of samples containing materials whose volatilities cover a wide range. PTGC produced better chromatograms and was faster than isothermal gas chromatography. PTGC did not achieve separations which were not possible by isothermal gas chromatography. Operating parameters for a PTGC residue screening operation were determined. Relative retention times at these conditions are given for 22 pesticides. Other advantages of the PTGC instrumentation are noted.

Collaborative Study of a Gas Chromatographic Determination of Methylene Chloride, Ethylene Dichloride, and Trichloroethylene Residues in Spice Oleoresins

1968 ◽  
Vol 51 (4) ◽  
pp. 825-828
Author(s):  
Laura A Roberts
Keyword(s):  
Methylene Chloride ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Chromatographic Column ◽  
Ethylene Dichloride ◽  
Gas Chromatograph ◽  
Porapak Q ◽  
Relative Retention ◽  
Solvent Residues

Abstract A method for the gas chromatographic determination of methylene chloride, ethylene dichloride, and trichloroethylene residues in spice oleoresins was studied collaboratively. The method employs a microcoulometric gas chromatograph fitted with a Porapak Q column and is based on the volatility of the solvent residues, their relative retention times on a polyaromatic bead chromatographic column, and their detectability by a halide-specific microcoulometric method. Recoveries were adequate when the method was closely followed; recoveries were erratic when collaborators deviated from the method. Further study is recommended.

Foam-Charcoal Chromatography for Analysis of Polychlorinated Dibenzodioxins in Herbicide Orange

1978 ◽  
Vol 61 (1) ◽  
pp. 32-38
Author(s):  
James N Huckins ◽  
David L Stalling ◽  
William A Smith
Keyword(s):  
Electron Capture ◽  
Polyurethane Foams ◽  
Dichlorophenoxyacetic Acid ◽  
Activated Alumina ◽  
Average Recovery ◽  
Polychlorinated Dibenzodioxins ◽  
Butyl Esters ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Liquid Chromatographic ◽  
Additional Sample

Abstract Herbicide Orange (HO) is a mixture of n-butyl esters of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). The 2,4,5-T is known to contain 2,3, 7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and other chlorinated aromatic contaminants. Adsorption of TCDD from HO on small amounts of powdered charcoal results in sample cleanup adequate for electron capture gas-liquid chromatographic (GLC) analysis. Column flow restrictions with powdered charcoal are overcome by using polyurethane foams as a dispersive support, HO is dissolved in chloroform and percolated through a column containing a mixture of PX-21 activated carbon suspended on clean polyurethane foam (14.9% charcoal/ 85.1% foam, w/w). Subsequently, the column is washed with benzene, and TCDD is recovered with toluene-benzene (1+1). Samples containing less than 1 μg TCDD/ml required additional sample cleanup on activated alumina prior to GLC analysis. The average recovery of TCDD determined from 4 replicate radiometric measurements was 91.4% (standard error = 4.0). TCDD residues greater than 0.02 μg/ml in HO samples were quantitated by electron capture GLC after cleanup. The presence of TCDD and pentachlorodibenzo-p-dioxin was confirmed by GLC-mass spectroscopy. In addition, tetrachloro- and pentachlorodibenzofurans were inferred by GLC-mass spectrometry.

Microdetermination of Bioethanomethrin

1975 ◽  
Vol 58 (4) ◽  
pp. 781-784
Author(s):  
Donald A George ◽  
Leslie M Mcdonough
Keyword(s):  
Spectral Data ◽  
Electron Capture ◽  
Synthetic Pyrethroid ◽  
Pyrethroid Insecticide ◽  
Electron Capture Detector ◽  
Gas Chromatograph ◽  
Mass Spectral Data ◽  
Acid Moiety ◽  
Mass Spectral

Abstract A microanalytical method was developed for the determination of the experimental synthetic pyrethroid insecticide Bioethanomethrin ((5- benzyl-3-furyl) methyl trans-(+)-3-( cyclopentylidenemethyl)-2,2 -dimethylcyclopropanecarboxylate). After saponification, trichloroacetyl chloride is used to form an ester from the alcohol moiety, and trichloroethanol is used to form an ester from the acid moiety. Infrared and mass spectral data support the expected structures of the derivatives formed. Nanogram sensitivity is realized by utilizing a gas chromatograph with an electron capture detector.

Collaborative Study of the Sweep Co-Distillation Cleanup for Chlorinated Pesticide Residues in Edible Fats and Oils

1969 ◽  
Vol 52 (4) ◽  
pp. 790-797
Author(s):  
Bernadette Malone ◽  
Jerry A Burke
Keyword(s):  
Soybean Oil ◽  
Electron Capture ◽  
Pesticide Residues ◽  
Collaborative Study ◽  
Fats And Oils ◽  
Heptachlor Epoxide ◽  
Chlorinated Pesticides ◽  
Edible Fats

Abstract A collaborative study was made of the sweep co-distillation cleanup method for multiple residues of chlorinated pesticides in edible fats and oils with determination by electron capture GLC using a column of 15% QF-1/10% DC-200 on 80–100 Gas Chrom Q. Heptachlor epoxide, p,p’-DDE, dieldrin, p,p’-TDE, and p,p’-DDT were added at two levels to butterfat and soybean oil. Mean recoveries of pesticides ranged from 86.0 to 102.1% in soybean oil and 86.4 to 98.8% in butter.

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