ABSTRACT

Herbicides are chemicals used to control weeds in

several areas such as agriculture, forestry, industry,

and transport. These compounds control weeds in a

variety of ways, showing different modes of action,

selectivity, and application characteristics. Soil-applied

herbicides are absorbed by roots or emerging shoots

and foliage-applied herbicides are absorbed into the

leaves, where they may be translocated to other parts

of the plant. The herbicides can be grouped according

to their chemical structures in different herbicide

classes (1). Table 1 shows the chemical structures of

the major classes of herbicides. The use of herbicides in agriculture has advantages,

such as an increase in the quantity and quality of food

crops. Nevertheless, herbicides are toxic substances

and, as a consequence of the large quantities used, their

residues can be present in foods. To protect consumers’

health, maximum residue limits (MRLs) have been

established at international and national levels. The

physicochemical properties of these compounds and

their MRLs (2-5) are given in Table 2. Residues of herbicides will persist in the plant for

a variable time, depending on their physicochemical

properties and on the environmental conditions.

Herbicides of a wide range of polarities have to be

determined in complex matrices, such as food, at very

low levels. Knowledge of their physicochemical prop-

erties is important to develop analytical procedures

for the determination of herbicide residues. Several