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METHOD ABSTRACTS117 / PARAQUAT AND DIQUAT IN WATERDIRECT INJECTION METHODParaquat and Diquat are widely used in agriculture and industry. They are employed as contact herbicides, as harvest aids,for pasture renovation and for aquatic weed control. Their environmental persistence allows for contamination of watersupplies; wells, lakes, rivers, etc. Since Paraquat is a Class I Toxin and Diquat is a Class II Toxin, water resources must bemonitored for the presence of these herbicides.This method employs ion exchange chromatography so ltration is the only sample preparation necessary. Also, since bothParaquat and Diquat have a xed +2 charge, 2 mL can be injected without peak degradation. Post-column derivitizationimproves sensitivity and greatly improves selectivity by shifting the detection to longer wavelengths.METHODAnalytical ConditionsColumn: ALKION column 4 x 150mm,Catalog No. 9410917, Guard column 3 x 20mm,Catalog No. 9493020Temperature: 50 °CFlow Rate: 0.8 mL/minMobile Phase:1700-1101, Potassium buffer, K011700-1102, Potassium titrant, K021700-1103, Potassium ionic strength adjuster, K03Injection Volume: 2 mLPost-column ConditionsPost-column System: Pinnacle PCXReaction Dwell: 0.15 mLTemperature: 35 °CReagent: 300 mg/L Sodium Dithionite in0.3 M Sodium HydroxideFlow Rate: 0.3 mL/minDetection: 395 nm for Paraquat and 378 nm for DiquatWithout post-column derivatization:257 nm for Paraquat and 308 nm for DiquatDiquatParaquat0 2 4 6 8 10 12CONDITIONSTIME (Min) 1700-1101 % 1700-1102 % 1700-1103 % IPA %0 31.5 53.5 0 1510 28 47 10 1515 28 47 10 1515.1 0 85 10 517 0 85 10 517.1 31.5 53.5 0 15min125PRODUCT CATALOGPICKERING LABORATORIES10/11