Gas Chromatographic Determination of 2,4-D and 2,4,5-T and Their Derivatives in Commercial Formulations

1965 ◽  
Vol 48 (2) ◽  
pp. 327-333
Author(s):  
Patricia L Pursley ◽  
E D Schall
Keyword(s):  
Gas Chromatography ◽  
Chromatographic Analysis ◽  
Methyl Esters ◽  
Chromatographic Determination ◽  
Dichlorophenoxyacetic Acid ◽  
Alkyl Esters ◽  
Boron Trichloride ◽  
Acid Gas ◽  
Gas Chromatographic Analysis

Abstract A solution of boron trichloride in methanol was employed for the complete transcsterification of 2,4-D and 2,4,5-T esters to the corresponding methyl esters. Gas chromatographic analysis of the methyl esters permitted mixtures of 2,4-D and 2,4,5-T esters in commercial formidations to be analyzed both qualitatively and quantitatively with no sample cleanup. The method is highly specific and detected the presence of other contaminating isomers of dichlorophenoxyacetic acid. Gas chromatography was also used to qualitatively analyze mixtures of various alkyl esters of 2,4-D.

scholarly journals Unusual Regularity in GC Retention of Simple Amino Acid Derivatives

2019 ◽  
Vol 6 (1) ◽  
pp. 3-14 ◽  
Author(s):  
Igor G. Zenkevich ◽  
Nino G. Todua ◽  
Anzor I. Mikaia
Keyword(s):  
Gas Chromatography ◽  
Retention Index ◽  
Methyl Esters ◽  
Elution Order ◽  
Alkyl Esters ◽  
Methyl Group ◽  
The Difference ◽  
Direct Use ◽  
Derivatives Of

Background: Application of simple regularities and general principles along with direct use of reference gas chromatography retention index data for reliable structure determination of compounds can be enhanced by determination of new regularities that are specific to certain structural elements. Objective: Revelation and interpretation of an anomaly in the elution order of alkyl esters of alkoxycarbonyl derivatives of glycine and alanine on standard and semi-standard non-polar phases. Method: Preliminary derivatization of amino acids to alkyl esters of N-alkoxycarbonyl analogs and interpretation of their gas chromatographic characteristics. Results: Alkyl esters of N-alkoxycarbonyl derivatives of alanine (Alkyl = C2H5, n- and iso-C3H7) elute prior to the same derivatives of glycine, despite the presence of an additional methyl group at C(2) in the molecule. Elution order is reversed for methyl esters of N-methoxycarbonyl derivatives. Conclusion: It is established that the peculiar behavior of alkyl esters of N-alkoxycarbonyl derivatives of glycine and alanine agrees with the concepts of gas chromatography and the known retention index regularities of organic compounds. A decrease of retention index values is a result of an introduction of an additional methyl group to a carbon atom connected to two polar fragments in a molecule like CH2XY. The dependence of the difference of retention index values for homologs of the types of CH3-CHXY and CH2XY vs. the total mass of fragments (X + Y) is similar to those for other sub-groups of analytes.

New Approach to Derivatization and Gas-Chromatographic Analysis of Barbiturates

1974 ◽  
Vol 20 (2) ◽  
pp. 192-194 ◽  
Author(s):  
Richard H Greeley
Keyword(s):  
Gas Chromatography ◽  
Chromatographic Analysis ◽  
Methyl Esters ◽  
Soluble Salts ◽  
New Approach ◽  
Gas Chromatographic Analysis ◽  
Alkyl Derivatives ◽  
High Resolution Gas Chromatography ◽  
Alkyl Iodides ◽  
Derivatives Of

Abstract A recently developed procedure for alkylation of organic acids has proven extremely successful for preparation of volatile alkyl derivatives of the barbiturates for gas-chromatographic analysis. Soluble salts are formed in a mixture of N,N-dimethylacetamide and methanol. These in turn react rapidly with alkyl iodides to form the corresponding alkyl derivatives. The butyl derivatives of barbiturates, prepared in this manner, are separable by high-resolution gas-chromatography. Any of 14 barbiturates can be determined simultaneously or separately (although there is some overlap with certain uncommon barbiturates). The butyl derivatives of several barbiturates that are unresolved in the form of underived compounds or methyl esters can be resolved, thus overcoming many previous analytical limitations.

Direct Gas-Liquid Chromatographic Determination of Water-Soluble Vitamin K3 in Feed Premixes

1972 ◽  
Vol 55 (6) ◽  
pp. 1219-1222
Author(s):  
Victor W Winkler ◽  
John M Yoder
Keyword(s):  
Gas Chromatography ◽  
Chromatographic Analysis ◽  
Chromatographic Determination ◽  
Water Soluble ◽  
Vitamin K3 ◽  
Water Soluble Vitamin ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Pyrolytic Product

Abstract A method for the quantitative determination of menadione bisulfite addition products in feed premixes is presented. The menadione bisulfite compound is extracted with methanol from the premix and is determined by gas chromatography directly without pretreatment with alkali. The principle of the method is on-column pyrolysis of menadione bisulfite and subsequent gas chromatographic analysis of the pyrolytic product, menadione.

scholarly journals Determination of Trace 2,4-Dichlorophenoxyacetic Acid in Fresh Produce by Gas Chromatography with Boron Trichloride/2- Chloroethanol Derivatization

1998 ◽  
Vol 81 (1) ◽  
pp. 93-98 ◽  
Author(s):  
Keh-Chuh Ting ◽  
Peng K Kho
Keyword(s):  
Gas Chromatography ◽  
Retention Time ◽  
Signal To Noise Ratio ◽  
Methyl Esters ◽  
Fresh Produce ◽  
Electron Capture Detection ◽  
Dichlorophenoxyacetic Acid ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Peak Retention Time

Abstract 2,4-Dichlorophenoxyacetic acid (2,4-D) residues in fresh produce is officially analyzed as its methyl ester form by gas chromatography with electron capture detection (GC-ECD). Because of safety concerns with diazomethane, the reagent used to form methyl esters, a less toxic and dangerous reagent, BCI3/2-chloroethanol, was considered. With this alternative reagent, the detecting product is a 2-chloroethyl ester. Compared with the methylester, the 2-chloroethylester has a longer retention time and a better signal-to-noise ratio for trace level analysis by GC-ECD. However, the reagent produces too many unwanted background peaks. If peak retention time is the only information available to identify the residue in case of litigation, the presence of too much background noise increases the ambiguity of identification. Therefore, confirmation by interpretation of the mass spectrum and determination of the compound structure is necessary to ensure the validity of the method. Ten commodities were fortified with 2,4-D at 0.1 ppm. Recoveries of 2-chloroethyl esters and methyl esters were 91 and 92%, respectively. The method is safe, simple, and robust.

Gas Chromatographic Determination of Trace Amounts of the Insect Chemosterilants Tepa, Metepa, Methiotepa, Hempa, and Apholate and the Analysis of Tepa in Insect Tissue

1966 ◽  
Vol 49 (5) ◽  
pp. 1046-1052
Author(s):  
Malcolm C Bowman ◽  
Morton Beroza
Keyword(s):  
Chromatographic Analysis ◽  
Chromatographic Method ◽  
Chromatographic Determination ◽  
Radiometric Method ◽  
Detector Response ◽  
Flame Photometric Detector ◽  
Methanol Extracts ◽  
Gas Chromatographic Analysis ◽  
Gas Chromatographic Method

Abstract A gas chromatographic method, sensitive to as little as 0.1 nanogram, was devised for analysis of the insect chemosterilants tepa, metepa, methiotepa, hempa, and apholate. The method is needed to monitor amounts and persistence of chemosterilant in treated insects. The procedure uses a flame-photometric detector. Response is linear (phosphorus analysis) between 0.1 and at least 200 ng. The procedure was shown to be directly applicable to analysis of methanol extracts of insects fed tepa. Concurrent gas chromatographic and radiometric analyses indicated that the radiometric method would not give satisfactory results without a suitable cleanup, whereas virtually no cleanup was required for the gas chromatographic analysis. The gas chromatographic method is rapid and easily carried out.

scholarly journals Gas chromatographic determination of some carboxylic acids: comparison between solution and headspace analysis

Chemija ◽  
2019 ◽  
Vol 30 (4) ◽  
Author(s):  
Birutė Bugelytė ◽  
Karolina Ilonina ◽  
Vilius Poškus ◽  
Vida Vičkačkaitė
Keyword(s):  
Gas Chromatography ◽  
Carboxylic Acids ◽  
Chromatographic Analysis ◽  
Headspace Analysis ◽  
Chromatographic Determination ◽  
The Other ◽  
Headspace Gas Chromatography ◽  
Solid Samples ◽  
Headspace Gas

Direct and headspace gas chromatographic analysis is compared for the determination of lactic, oxalic, succinic, malic and citric acids. For better chromatographic behaviour, prior to GC analysis carboxylic acids were derivatized using BSTFA as a silylation reagent. Three solvents – acetone, diethyl ether and dimethylformamide – were tested as a derivatization medium and DMF was considered as the best. Derivatization conditions were optimized and analytical characteristics of the direct gas chromatographic determination of analytes in solutions were determined. The method was applied for the determination of citric acid in food. For the analytes dissolved in DMF, the headspace gas chromatographic determination was not sensitive enough. Concentrations of the derivates in the headspace were very low, thus the limits of detection were high and the method was not of practical use. On the other hand, headspace gas chromatography can be applied for identifying of carboxylic acids in solid samples.

Gas Chromatographic Determination of Isoprene, Acetaldehyde and Acrolein from the Gaseous Phase of Cigarette Smoke - Gaschromatographische Bestimmung von lsopren, Acetaldehyd und Acrolein aus der Gasphase von Cigarettenrauch

1976 ◽  
Vol 8 (6) ◽  
Author(s):  
H. J. Klimisch ◽  
H. Wernicke ◽  
K. Meißner
Keyword(s):  
Quantitative Determination ◽  
Cigarette Smoke ◽  
Gaseous Phase ◽  
Chromatographic Analysis ◽  
Sampling Technique ◽  
Chromatographic Determination ◽  
Gas Chromatographic Analysis

AbstractBy means of a special sampling technique with a cooled preliminary column parts of each puff from a cigarette are collected. With the aid of subsequent gas chromatographic analysis a quantitative determination of acrolein, acetaldehyde and isoprene from the gaseous phase is effected. The content of these three substances in some trial cigarettes is discussed.

Gas-Liquid Chromatographic Determination of β-Asarone, A Component of Oil of Calamus, in Flavors and Beverages

1973 ◽  
Vol 56 (5) ◽  
pp. 1281-1283
Author(s):  
Damon Larry
Keyword(s):  
Solvent Extraction ◽  
Chromatographic Analysis ◽  
Steam Distillation ◽  
Chromatographic Determination ◽  
Chromatographic Peak ◽  
Average Recovery ◽  
Gas Chromatographic Analysis ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A method has been developed for the detection and quantitation of β-asarone in vermouths. Volatiles are isolated by steam distillation, and β-asarone is separated from interfering substances by solvent extraction and subjected to gas chromatographic analysis. Quantitation of samples containing 5–100 ppm β-asarone was achieved by direct chromatographic peak comparisons with standards prepared in 20% ethanol-water, which are treated the same as samples. Average recovery from light and dark vermouths spiked at 5, 15, 25, and 100 ppm was 98.8%.

Determination of 2-Methoxy-3-alkylpyrazines in Carrot Products by Gas Chromatography/Nitrogen–Phosphorus Detection

1994 ◽  
Vol 77 (2) ◽  
pp. 416-420 ◽  
Author(s):  
Eric D Lund
Keyword(s):  
Gas Chromatography ◽  
Chromatographic Analysis ◽  
Threshold Value ◽  
Purge And Trap ◽  
Gas Chromatographic Analysis ◽  
Freeze Dried ◽  
Nitrogen Phosphorus

Abstract The 2-methoxy-3-alkylpyrazines in 6 types of carrot products were determined by a stripping–selective trapping procedure followed by purge-and-trap gas chromatographic analysis with an NP detector. The aroma threshold of one of the principal pyrazines, 2-methoxy-3-sec-butylpyrazine, in a carrot medium was 0.19 ng/g. The concentrations of this compound in whole-carrot products were 0.43 (fresh), 0.291 (canned, cooked), and 0.224 ng/g (frozen). A diced, cooked, and freeze-dried product contained 0.070 ng/g. All of these products contained only this pyrazine. In contrast, a shredded, bagged product contained 2-methoxy-3-isopropylpyrazine as the sole pyrazine (0.32 ng/g), and a sliced, dried product contained a mixture of 3 pyrazines: 2-methoxy-3-sec-butyl- (0.109 ng/g), 2-methoxy-3-iso-propyl- (0.176 ng/g), and 2-methoxy-3-isobutylpyra-zine (0.029 ng/g). The pyrazine concentrations in most of these products (except the freeze-dried product) exceeded the threshold value.

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