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Determination of vapour pressure and henry's constant of deltamethrin technical using gas saturation method with HPLC detection

Tentu. Nageswara Rao, N.Krishna Rao, G.Kumar, Karri.Apparao, Prathipati. Revathi

The vapour pressure of deltamethrin technical was conducted using the gas saturationmethod based on the regulatoryOPPTS 830.7950 and EEC A.4 guidelines. According to this method the packed vapour saturator columns were connected to vapour pressure apparatus and the columns were exposed to different flow rates. The flowrates were 20 (F1), 40(F2) and 60 mL/min (F3). This set upwas equilibrated at 30°C over night. After equilibration the nitrogen gas outlet from the column was connected to the trapping system. Nitrogen gas was continuously passed through each saturator column for 7 days. The maintained flow rate and temperatures were monitored during the study period. At the end of 7 days, the trapping material was collected from the trapping tube by eluting the glass columns using 100 mL of acetone. The collected elute was concentrated using rotary vacuum evaporator to near dryness, and diluted to 10 mL by using acetonitrile. The samples were analysed using validated HPLC. The vapour pressure of deltamethrin technical, was determined to be 1.63x10-5 Pa at 20°C and 2.05x10-5 Pa at 30°C and the henryÂÂ’s law constant of the test item, deltamethrin technical, was determined to be 2.967x103 at 20°C and 2.517x103 at 30°C.