title: Analysis of pesticide residues by chemical derivatization. V. Multiresidue analysis of eight phenoxyalkanoic acid herbicides in natural waters.
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.
mesh_terms: D002849:Chromatography, Gas; D006016:Glycolates / Q000032:analysis*; D006540:Herbicides / Q000032:analysis*; D007202:Indicators and Reagents; D010573:Pesticide Residues / Q000032:analysis*; D014873:Water Pollutants / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D006016:Glycolates; D006540:Herbicides; D007202:Indicators and Reagents; D010573:Pesticide Residues; D014873:Water Pollutants; D014874:Water Pollutants, Chemical