Chemical Derivatization Analysis of Pesticide Residues. Part XI. An Improved Method for the Determination and Confirmation of Acidic Herbicides in Water

Abstract

A procedure for the determination and confirmation of acidic herbicides In water Is described. This method is applicable to 13 commonly used herbicides, including the monochlorinated ones, at μg/L and sub-μg/L levels. The water sample is acidified to pH < 2 and extracted by dichloromethane. The herbicides are converted into their pentafluorobenzyl (PFB) derivatives and the products are cleaned up on a silica gel column. A gel permeation cleanup using a Bio-Beads S-X3 column is included to remove the PFB esters of fatty acids, which are the major Interferences in the final analysis using electron capture detection (ECD). Confirmation of herbicides employing electron Impact and negative ion chemical lonlzatlon/ mass spectrometry (NICI/MS) is discussed and applied to river water samples. The mean recoveries of herbicides for water samples fortified at 1 and 0.1 μg/L range from 45 to over 90%. The detection limit of herbicides in natural water samples is 0.05 μg/L with ECD and 0.02 μg/L with NICI/MS.

Enantiomeric separation of chiral phenoxy acid herbicides by electrokinetic chromatography. Application to the determination of analyte-selector apparent binding constants for enantiomers

“…Phenoxy acids are widely used in agriculture as selective herbicides. Due to their solubility in water, they can move in agriculture ecosystems, causing surface and ground waters pollution [1]. Their toxicity and herbicidal effects have been studied in detail, and many efforts have been made to develop reliable and sensitive methods for determining phenoxy acids in various matrices, most of these methods being based on high performance liquid chromatography (HPLC) or gas chromatography (GC) [2±9].…”

Use of Stopped-flow Fluoroimmunoassay in Pesticide Determination

“…The availability of simple and fast methods for the determination of this pesticide is of great interest as it is a suspected carcinogen. 5 Its determination is generally carried out by using gas chromatographic methods [6][7][8] which, although allowing very low detection limits to be obtained, require a previous derivatization step because of the thermal instability and low volatility of 2,4-D, thus making their automation difficult. The main purpose of this work was to develop a stopped-flow fluoroimmunoassay of 2,4-D and illustrate its application to direct pesticide determination in fruit juice samples, with high throughput.…”

Automated on-line in-tube solid-phase microextraction followed by liquid chromatography/electrospray ionization-mass spectrometry for the determination of chlorinated phenoxy acid herbicides in environmental waters

“…The methods used to determine chlorinated phenoxy acid herbicides, including EPA Methods 8150 6 and 8151, 7 involve gas chromatography (GC) with electron capture detection (ECD) [8][9][10][11] and mass spectrometric detection. [12][13][14][15] However, for GC methods, a prior derivatization step using diazomethane, alkyl and haloalkyl halides (e.g.…”