DETERMINATION OF CHLORINATED PHENOXY ACID AND ESTER HERBICIDES IN SOIL AND WATER BY LIQUID-CHROMATOGRAPHY PARTICLE BEAM MASS-SPECTROMETRY AND ULTRAVIOLET-ABSORPTION SPECTROPHOTOMETRY

Eight chlorinated phenoxy acid and three ester herbicides are determined in soil and water by liquid chromatography with UV absorption for quantitation and particle beam mass spectrometry for confirmation. Chromatography (C-18 reversed-phase column, 22 cm x 2.1 mm, water with methanol or acetonitrile and acetic acid mobile phase, 0.25 mL/min flow) with UV detection (230 nm) gives quantitation limits of 12-80 ng in 10-mu-L injected volume (corresponding to 4.8-32 ppb in 125 mL of water and 20-133 ppb in 30 g of soil and 500-mu-L of final extract volume) with four-point calibration (R > 0.99). Full scan electron ionization particle beam mass spectra are given for chlorinated phenoxy acids at 1.25-mu-g each on-column, showing molecular and phenoxy (base) ions. Both acids and esters are efficiently and cleanly extracted from soil and water with ethyl acetate, and the esters are base hydrolyzed before analysis. The average recovery of eight carboxylic acids spiked into water at 33.3, 1.0, and 0.1 ppm and spiked into soil at 33.3 and 1.0 ppm is 78% (average standard deviation 4.2%). The average recovery and ester hydrolysis efficiency for the three esters 2,4-D mixed isobutyl, 2,4,5-T butoxyethanol ether, and 2,4-DB isobutyl spiked at the same levels in soil and water is 88% (average standard deviation 10%).