Improved spectrophotometric determination of paraquat in drinking waters exploiting a Multisyringe liquid core waveguide system

The proposed methodology is based on the production of a blue free radical by reaction of Pq2+ with ascorbic acid (partially oxidized with potassium iodate) in basic medium. Limits of detection and quantification as low as 0.7 and 2.3 μg L−1, were obtained respectively. The working range is linear up to a concentration of 250 μg L−1 of Pq2+. The injection throughput of the proposed method is 34 h−1. The results obtained with the LCW are compared with those using a conventional 1 cm flow cell. The automation of standard addition procedures has been studied and implemented for samples causing matrix effects. Finally the proposed system has been applied to the determination of paraquat in drinking water samples.