Sensitive determination of diquat by a kinetic method using the stopped-flow mixing technique.
A simple, sensitive, selective, fast and inexpensive assay for the determination of diquat is proposed. The method is based on the reduction of the herbicide 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 kinetic data can be obtained in only 7 s, meaning that the method can be automated. 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 demonstrated by determining the herbicide in different kinds of samples.
Pérez-Ruiz
T
T
Department of Analytical Chemistry, Faculty of Chemistry, University of Murcia, 30071 Murcia, Spain. tpr@fcu.um.es
Martínez-Lozano
C
C
Tomás
V
V
Fenoll
J
J
D004178:Diquat / Q000032:analysis* / Q000097:blood; D004785:Environmental Pollutants / Q000032:analysis* / Q000097:blood; D005470:Fluorometry / Q000379:methods; D006540:Herbicides / Q000032:analysis* / Q000097:blood; D012989:Soil Pollutants / Q000032:analysis; D011198:Solanum tuberosum / Q000737:chemistry; D014873:Water Pollutants / Q000032:analysis
D004785:Environmental Pollutants; D006540:Herbicides; D012989:Soil Pollutants; D014873:Water Pollutants; D004178:Diquat