Determination of 2,4-Dichlorophenoxyacetic Acid and 2-(2,4,5-Trichlorophenoxy)propionic Acid in Citrus by Electron Capture Gas Chromatography

1966 ◽  
Vol 14 (4) ◽  
pp. 374-377 ◽  
Author(s):  
W. R. Meagher
Keyword(s):  
Gas Chromatography ◽  
Propionic Acid ◽  
Electron Capture ◽  
Dichlorophenoxyacetic Acid ◽  
2,4 Dichlorophenoxyacetic Acid

scholarly journals Simultaneous Determination of 2,4-D, Dicamba, and Mecoprop in Soil Leachates by Gas Chromatography with Electron Capture Detection

1996 ◽  
Vol 79 (4) ◽  
pp. 998-1004
Author(s):  
Moo-Ki Hong ◽  
Myung-Chul Kim ◽  
Albert E Smith
Keyword(s):  
Gas Chromatography ◽  
Reaction Time ◽  
Simultaneous Determination ◽  
Electron Capture ◽  
Electron Capture Detection ◽  
Dichlorophenoxyacetic Acid ◽  
Molecular Response ◽  
Peak Resolution ◽  
2,4 Dichlorophenoxyacetic Acid

Abstract Capillary gas chromatography (GC) with electron capture detection (ECD) and mass selective detection (MSD) was used for simultaneous determination of 2,4-dichlorophenoxyacetic acid (2,4-D), 3,6-dichloro-2-methoxybenzoic acid (dicamba), and (±)2-(4-chloro-2-methylphenoxy)propanoicacid (mecoprop) extracted from soil leachates. The 2,2,2-trif luoroethanol (TFE) esters of the acid analytes were synthesized by using H2SO4 as the catalyst. Efficiency of derivatization and instrumental molecular response were compared for herbicides methylated with boron trifluoride-methanol (14%, w/v), H2S04-methanol (33%, v/v), and diazomethane. The molecular integrity of TFE-2,4-D, TFE-dicamba, and TFE-mecoprop in the mixture was confirmed by GC-MSD. The TFE-esterification efficiency was maximized by adjusting the volume of H2SO4, the reaction time, and the reaction temperature. Optimal efficiency for the herbicide mixture was obtained by adding 1 m└ H2SO4 and 1 m└ TFE to the dried extract and allowing the reaction to proceed at 22�C for 8 h or by adding 0.5 m└ H2SO4 and 1 m└ TFE at 60°C for 120 min. Maximum esterification efficiency required an increased temperature and a decreased reaction time. The sensitivity of GC-ECD was about 2-20 times greater in determining TFE esters than in determining methyl ester derivatives. The herbicides were extracted simultaneously from soil leachates previously spiked with the analytes and esterified to TFE derivatives. Herbicide recovery, peak resolution, and detector sensitivity were excellent without column cleanup procedures.

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.

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