Analysis of Pesticide Residues by Chemical Derivatization. V. Multiresidue Analysis of Eight Phenoxyalkanoic Acid Herbicides in Natural Waters

1977 ◽  
Vol 60 (5) ◽  
pp. 1070-1076 ◽  
Author(s):  
Haig Agemian ◽  
Alfred S Y Chau
Keyword(s):  
Natural Waters ◽  
Chromatographic Determination ◽  
Multiresidue Analysis ◽  
Boron Trichloride ◽  
Advantages And Disadvantages ◽  
Pentafluorobenzyl Bromide ◽  
Extraction Scheme ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Acid Herbicides

Abstract A multiresidue method is presented for the gas-liquid chromatographic determination of phenoxyalkanoic acid herbicides in natural waters. Extraction efficiencies of different organic solvents are considered in developing a solvent extraction scheme for these herbicides from water. Reactions for derivatizing these compounds by using pentafluorobenzyl bromide, boron trichloride-2-chloroethanol, and dicyclohexylcarbodiimide-2-chloroethanol were studied in order to obtain extracts with low blanks to provide the lowest detection limits. Advantages and disadvantages of the 3 methods are discussed. Retention times are twice as long for the pentafluorobenzyl (PFB) esters as for the 2-chloroethyl (2-Cl) esters under the same conditions, although electron capture sensitivity to the former was greater. The PFB esters are easier to form, but the 2-Cl reaction is more specific for these herbicides. Solutions from the boron trichloride reaction gave the cleanest blanks.

Gas-Liquid Chromatographic Determination of Sodium Fluoroacetate (Compound 1080)

1980 ◽  
Vol 63 (1) ◽  
pp. 49-55
Author(s):  
Iwao Okuno ◽  
Dennis L Meeker
Keyword(s):  
Liquid Chromatography ◽  
Tissue Sample ◽  
Chromatographic Determination ◽  
Gas Liquid Chromatography ◽  
Tissue Samples ◽  
Fluoroacetic Acid ◽  
Pentafluorobenzyl Bromide ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract An analytical method is described for the determination of Compound 1080 (sodium fluoroacetate) residues in 1–10 g tissue. Sample extracts of tissues are cleaned up with silica gel, and Compound 1080 (as fluoroacetic acid) is separated by a micro-distillation procedure. The fluoroacetic acid in the distillate is derivatized with pentafluorobenzyl bromide to form pentafluorobenzyl fluoroacetate which is measured by electron capture gas-liquid chromatography. Recoveries of sodium fluoroacetate from fortified tissue samples averaged about 25%. Despite the limited recoveries, results were quite reproducible, and levels as low at 2 ppm were determined in fortified 1 g samples, and 0.2 ppm in 10 g samples. The method is relatively simple and has been used routinely in our laboratory for the analysis of various types of samples such as grain, and tissues from birds, rodents, and larger animals.

Gas-liquid chromatographic determination of bupivacaine and lidocaine in plasma.

1978 ◽  
Vol 24 (9) ◽  
pp. 1573-1575 ◽  
Author(s):  
E Zylber-Katz ◽  
L Granit ◽  
M Levy
Keyword(s):  
Methylene Chloride ◽  
Plasma Concentrations ◽  
Extraction Procedure ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Liquid Chromatographic Method ◽  
Extraction Scheme ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A modified gas-liquid chromatographic method for determining plasma concentrations of bupivacaine and lidocaine is described, with cyclizine as an internal standard. The extraction procedure requires no solvent evaporation, thus overcoming the problem of drug volatility. Concentrations as low as 0.1 mg/liter can be determined. The plasma sample is made alkaline and extracted into n-hexane, re-extracted into a small volume of an aqueous acid phase, and finally extracted into 50 microliter of methylene chloride after alkalinization. The final extract is assayed by gas chromatography on a 5% OV-17 column. The extraction scheme of the present method eliminates interferences by endogenous plasma constituents.

Gas-Liquid Chromatographic Determination of 4-Chlorophenoxyacetic Acid Residues in Mung Bean Sprouts

1982 ◽  
Vol 65 (5) ◽  
pp. 1118-1121
Author(s):  
Yew-Sin Wong
Keyword(s):  
Ethyl Acetate ◽  
Mung Bean ◽  
Chromatographic Determination ◽  
Gas Chromatography Mass Spectrometry ◽  
Mung Bean Sprouts ◽  
Pentafluorobenzyl Bromide ◽  
Liquid Chromatographic Determination ◽  
Chlorophenoxyacetic Acid ◽  
Liquid Chromatographic ◽  
Bean Sprouts

Abstract A gas-liquid chromatographic (GLC) method is described for determining 4-chlorophenoxyacetic acid (CPA) residues in mung bean sprouts. The residues were extracted from samples by using ethyl acetate followed by liquid-liquid partition into 5% NaHCO3 solution. After acidification and reextraction with ethyl acetate, CPA was reacted with pentafluorobenzyl bromide (PFB-Br) to form the PFB derivative. The reaction mixture was separated on a silica gel column to remove excess reagent, and the derivative was eluted with a solution of 75% toluene in hexane. GLC separations were performed on a 3% OV-1 column at 230°C. As low as 10 pg CPA could be quantitated, which is equivalent to about 0.05 ppm at residue level, using an electron capture detector. Recoveries of CPA from fortified mung bean sprouts (0.05, 0.20, and 0.50 ppm) ranged from 71 to 107%. The PFB derivative was further identified by gas chromatography-mass spectrometry.

Gas-Liquid Chromatographic Determination of Thiabendazole and Methyl 2-Benzimidazole Carbamate in Fruits and Crops

1979 ◽  
Vol 62 (4) ◽  
pp. 769-773 ◽  
Author(s):  
Gwan H Tjan ◽  
John T A Jansen
Keyword(s):  
Ethyl Acetate ◽  
Chromatographic Determination ◽  
Gas Liquid Chromatography ◽  
Liquid Chromatography Mass Spectrometry ◽  
Liquid Liquid Extraction ◽  
Alumina Column Chromatography ◽  
Pentafluorobenzyl Bromide ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A method is described for the electron capture gas-liquid chromatographic determination of thiabendazole and methyl 2-benzimidazole carbamate (MBC) after derivatization with pentafluorobenzyl bromide (PFB-Br). The samples are extracted with ethyl acetate, and the residual thiabendazole, benomyl, and MBC are isolated by liquid-liquid extraction into dilute HC1. After neutralization and re-extraction with ethyl acetate, thiabendazole and MBC are reacted with PFB-Br to form the PFB derivatives. Alumina column chromatography was used to clean up extracts, and the derivatives could be detected as low as 5–10 pg. Recoveries were 95-98% from fruits fortified with 0.3-2.0 ppm thiabendazole; recoveries were 91–97% when 0.05–1.0 ppm benomyl/MBC were added to fruits/crops. The PFB derivatives were identified by gas-liquid chromatography-mass spectrometry.

Sign in / Sign up

Export Citation Format

Share Document