Square-Wave and Differential Pulse Oxidative Voltammetric Determination of Diquat and Paraquat in Alkaline Medium

✍ Scribed by Teresa Galeano Díaz; Augustina Guiberteau Cabanillas; Francisco Salinas

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 123 KB
• Volume: 12
• Category: Article
• ISSN: 1040-0397
• DOI: 10.1002/(sici)1521-4109(200005)12:8<616::aid-elan616>3.0.co;2-x

✦ Synopsis

Square-wave and differential pulse voltammetric methods are proposed for the determination of the herbicides paraquat and diquat, based on their oxidation peak at the glassy carbon electrode, following their degradation in strong alkaline medium. The potential values are near 0.31 V for paraquat and 0.37 V for diquat in SWV mode and near 0.24 V for paraquat and 0.31 V for diquat in the differential pulse voltammetric (DPV) mode. Once the in¯uence of the chemical conditions and instrumental variables were examined, two different procedures are proposed. The ®rst allows the determination of diquat between 0.05 and 1 mg mL À1 , using a 0.05 M sodium hydroxide concentration. In a stronger alkaline medium (1 M sodium hydroxide) both paraquat and diquat can be determined between 1 and 10 mg mL À1 . The determination of both compounds is carried out by application of the partial least squares (PLS) type 1 multivariate approach. After optimization of the parameters of the chemommetric procedures, the proposed methods are validated with synthetic samples and applied to determine these herbicides in a commercial formulation containing both compounds and in forti®ed river water samples.