Sample preparation for GC analysis of selected pesticides in surface water

A new isolation procedure for the determination of nitrogen/phosphorous con taining pesticides and organochlorine pesticides in water was tested, and s tatistical evaluation of the recoveries was performed. The procedure, desig ned specifically for the analysis of semi-volatile compounds in water conta ining Suspended Particulate Matter (SPM), utilizes a specially designed fil tration vessel coupled directly to an SPE cartridge. The studies were based on surface water samples (from the Vistula River) spiked with pesticides. SPM separation and analyte isolation/concentration were carried out in a sp ecial filtration vessel. Pesticides were sorbed both on the SPE cartridge a nd on the suspended matter. The cartridge and the filter with the suspended matter were extracted separately with a solvent, which enabled the determi nation of analyte distribution between the two. For organochlorine pesticid es, between 3 and 60 % of the initial amount was found on the filter, while the recoveries in the filtrate ranged from 30 to 98 %. Total recoveries of organochlorine pesticides from surface water samples spiked with pesticide s using the method described were high, ranging from 90 to 101 %. The amoun ts of nitrogen/phosphorus containing pesticides recovered from the filter w ere lower than 2 %, while those from the filtrate ranged from 69 to 92 %. T otal recoveries of nitrogen/phosphorus containing pesticides from surface w ater samples were high, ranging from 71 to 92 %.