A measured volume or weight of sample (approximately 1 liter for liquids, 10 to 30 grams for solids and sludges) is extracted by using the appropriate sample extraction technique specified in Methods 3510, 3540, and 3550. Method 3520 is not recommended for the extraction of aqueous samples because the longer chain esters (dihexyl phthalate, bis(2-ethylhexyl) phthalate, di-n-octyl phthalate, and dinonyl phthalate) tend to adsorb to the glassware and consequently, their extraction recoveries are <40 percent. Aqueous samples are extracted at a pH of 5 to 7, with methylene chloride, in a separatory funnel (Method 3510). Alternatively, particulate-free aqueous samples could be filtered through membrane disks that contain C,,,-bonded silica. The phthalate esters are retained by the silica and, later eldfed with acetonitrile. Solid samples are extracted with hexane/acetone (1:1) or methylene chloride/acetone (1:1) in a Soxhlet extractor (Method 3540) or with an ultrasonic extractor (Method 3550). After cleanup, the extract is analyzed by gas chromatography with electron capture detection (GC/ECD).