Development and validation of methods for the trace determination of phthalates in sludge and vegetables

A routine method which is simple, quick and precise has been set up and validated for phthalate analysis in environmental samples (tomato plants an d sewage sludges). Six phthalates have been studied simultaneously: dimethylphthalate, diethylp hthalate, dibutylphthalate, butylbenzylphthalate, di(ethyl)hexylphthalate and dioctylphthalate. Optim ization of sample, solvent extraction uses a Soxtec apparatus and extract purification with an S PE cartridge allows between 90 to 110 % recovery of phthalates. Precise, sensitive and sele ctive identification and quantifying of analytes is by GC-MS in SIM mode. This protocol allows analytes with concentrations as low as 10µg/kg Dry Matter (DM) to be determined from small (1 to 2 g DM) samples. This analytical method has been applied to the phth alate transfer study for agricultural recycling of sludges, where phthalate bioavailability has been s tudied in aquiculture using two types of experiments. Tomatoes have been grown in containers where the trace organics have been directly introduced as pure substances, and in a second expe riment under the same growth conditions, sewage sludge has replaced the pure substances. Tra nsfer of these trace organics has been followed into the various parts of the tomato plant and in g eneral only the DEHP is worthy of note although its percentage transfer remains very low even in an experiment designed to maximize this. Keys-words Phthalates, Extraction methods, Environmental analysis, Sewage sludge