Since
2,4-dichlorophenoxy acetic acid (2,4-D) was discovered in
the 1940s, 2,4-D and its derivatives remain among most commonly used
herbicides in the world. There have been recent increases in using
2,4-D products in a combination with other herbicides such as metribuzin
and acetochlor to control noxious weeds. However, accurate analysis
of 2,4-D isooctyl ester remains to be improved due to long analysis
time and rapid conversion of the ester to acid (i.e., under-reporting
residues). In this work, a simple hydrolysis procedure was introduced
to provide a quantitative hydrolytic rate of the ester (>95%) and
did not affect the other pH-sensitive compounds. Analysis parameters
and sample pretreatments were optimized for improved selectivity and
accuracy. The hydrolysis-QuEChERS (quick, easy, cheap, effective,
rugged, and safe) technique for multidetermination of 2,4-D isooctyl
ester, metribuzin, acetochlor, and 2-ethyl-6-methylaniline in corn
and soybeans via high performance liquid chromatography–tandem
mass spectrometry was established. The method had average recoveries
of 74–109% with relative standard deviations ≤13.5%
and limits of quantifications (LOQs) of 0.05 mg/kg. The terminal residues
of these compounds found in real edible matrixes were less than the
corresponding LOQs at harvest time. The risk quotients were far below
100%, indicating a low health risk to consumers.