Determination of Trace Phthalic Acid Monoesters in Sediments and Soils by GC-MS

A simple procedure for determining trace phthalic acid monoesters (PAMs) in sediments/soils was developed. The method used ultrasonic extraction, silylation derivatization, and GC-MS. After ultrasonic extraction, the supernatants were reextracted with dichloromethane, silylated, and did not require further clean-up before GC-MS analysis. Effects of parameters, such as extraction solvents, pH of water as extraction solvent and sediment/soil properties, on the recovery of PAMs were studied. Five sediments from Tianjin city and one red soil from Jiangxi province were used. The results showed that organic carbon (OC) content played an important role in the recovery of PAMs. The optimal extraction solvent for sediments/soils with >1% of OC content and high CEC was 0.01 M HCl aqueous solution and pure water was better for sediments/soils with <1% of OC content. In 5 g sediment/soil sample (dry weight), the method detection limit (MDL) was below 0.04 ng/g for mono-n-butyl phthalate (MBP) and 0.02 ng/g for mono-(2-ethylhexyl)-phthalate (MEHP). Average recoveries of MBP and MEHP were 81.6%-105.2% and 76.0%-95.6%, respectively, with relative standard deviations = 6.6%. MBP and MEHP in the sediment and soil samples studied were detected at levels of 9.257.1 and 13.0166.7 ng/g, respectively.