T. Perez-ruiz et al., Sensitive determination of diquat by a kinetic method using the stopped-flow mixing technique, ANALYST, 125(12), 2000, pp. 2372-2375
A simple, sensitive, selective, fast and inexpensive assay for the determin
ation of diquat is proposed. The method is based on the reduction of the he
rbicide to a strongly fluorescent monocation radical with sodium dithionite
. The initial rate of this reaction is directly proportional to the diquat
concentration. The stopped-flow mixing technique was used because the kinet
ic data can be obtained in only 7 s, meaning that the method can be automat
ed. The calibration graph is linear over the range 5-500 ng ml(-1) and the
precision (RSD) is close to 1.2%. The applicability of the method was demon
strated by determining the herbicide in different kinds of samples.