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Determination of metalaxyl and identification of adjuvants in wettable powder pesticide technical formulas

Pose-Juan, Eva, Rial-Otero, Raquel, Martínez-Carballo, Elena, López-Periago, Eugenio, Simal-Gándara, Jesús
Analytical and bioanalytical chemistry 2009 v.394 no.6 pp. 1535-1544
adjuvants, gas chromatography, liquid chromatography, liquid-liquid extraction, manufacturing, mass spectrometry, metalaxyl, monitoring, nonionic surfactants, quantitative analysis, runoff, screening, soil, wettable powders
Foliar runoff is one of the most important processes affecting off-target movement of fungicides. In this way, Ridomil® Gold Plus and Ridomil® Gold MZ are two types of wettable powder technical formulations which contain metalaxyl and they are used for such a purpose. A method for quantitative determination of metalaxyl in pesticide formulas has been developed, validated, and subsequently applied to Ridomil® Gold Plus and Ridomil® Gold MZ. The method employs liquid-liquid extraction followed by liquid chromatography coupled with UV detection (LC-UV), using gas chromatography coupled with mass spectrometry as confirmation technique and to carry out a screening of organic adjuvants of these two selected pesticide formulas. Metalaxyl of 26.5 and 41 g/kg was detected in Ridomil® Gold Plus and Ridomil® Gold MZ, close to the manufacture specified level of 25 and 40 g/kg, respectively. Activator and utility adjuvants were detected in these two wettable powder technical formulations. Only methyl-ester-based surfactants were found within the group of nonionic surfactants, but the long-term fates of most adjuvants in soils and elsewhere in the environment are largely unknown, partially because of the lack of long-term monitoring data.