HIGH-SPEED GAS EXTRACTION OF VOLATILE AND SEMIVOLATILE ORGANIC-COMPOUNDS FROM AQUEOUS SAMPLES

A device is described for high-speed gas extraction of volatile and se mivolatile organic compounds from aqueous samples. High-speed extracti on is achieved by the use of elevated temperatures. Large quantities o f water vapor produced at elevated temperatures are managed with a ref lux condenser, which efficiently removes water vapor without sample lo ss by returning the condensed water along with any cocondensed organic compounds to the extraction cell. The heated extraction cell uses a 1 -2-mL sample with an extraction gas now of typically 30 mL/min. Extrac tion temperatures as high as 95 degrees C can be used while maintainin g a dew point temperature of similar to 5 degrees C for the extraction gas and sample vapor leaving the device. Extraction profiles are obta ined by connecting the device directly to a name ionization detector. Extraction profiles for benzene show that quantitative recovery can be achieved in similar to 30 s at an extraction temperature of 90 degree s C. Large increases in recovery at higher extraction temperatures are also demonstrated for tridecane and ethyl alcohol. For analytical stu dies, the device is interfaced to a commercial cryofocusing inlet syst em for highspeed gas chromatography, if all the extraction gas is trap ped and injected into the separation column, detection limits for vola tile organic compounds typically are in the 50-200 parts-per-trillion range.