Concentration and determination of the propylene glycol butyl ether esters of 2,4-dichlorophenoxyacetic acid (PGBE 2,4-D) in air.

A method has been developed and validated for the determination of airborne propylene glycol butyl ether ester and the dipropylene glycol butyl ether ester of 2,4-dichlorophenoxyacetic acid. The method is designed to collect samples in the breathing zone of workers for 4 hours at 150 mL/min. using a tube containing 750 mg of Amberlite XAD-2 resin and a portable pump. Recoveries of 85.2% and 81.4% were obtained for the two esters over a range of 0.67 and 13.3 mg/m3 by desorption wih hexane. The extracts were analyzed by electron capture gas chromatography using a highly efficient and inert bonded Carbowax 20-M column packing. The recovery was not affected by 80% relative humidity or refrigerated storage for two weeks. Some loss in recovery was observed for the 0.67 mg/m3 level when samples were stored at room temperature for two weeks. The overall precision of the method for the two esters is +/- 17% and +/- 16% at the 95% confidence level.