Simultaneous Flow Injection Determination of Diquat and Paraquat in Foodstuffs, Natural Waters and Biological Fluids

Abstract

The reduction of diquat and paraquat with alkaline sodium dithionite has been applied to the simultaneous determination of both herbicides using a flow injection system. A dual-channel manifold with two detectors in parallel was used. The sample bolus is split into two subplug, one of the sub-boluses merges with a 0.1% sodium dithionite stream and routes to a spectrofluorimeter where diquat is determined. The other sub-bolus merges with a 0.5% sodium dithionite stream and routes to a spectrophotometer for the measurement of paraquat. The system allows 70 samples to be analysed per hour. Applications of the method to the determination of diquat and paraquat in real samples are reported.

Key Words:

• Diquat
• paraquat
• flow injection analysis
• spectrophotometry
• spectrofluorimetry