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New Fast-Screening Test Can Prevent Damage to Lab Equipment from Volatile Water Samples

A task group of Subcommittee D19.06 on Methods for Analysis for Organic Substances in Water has developed a new screening process technicians can use to protect analytical equipment from contamination by concentrated or out-of-range water samples.

In about three minutes, the results of new ASTM D 6889, Standard Practice for Fast Screening for Volatile Organic Compounds in Water Using Solid Phase Microextraction (SPME), estimates the presence of analyte concentrations that can contaminate purge-and-trap or headspace analytical systems.

“The contamination of sensitive analytical instrumentation performing purge-and-trap or headspace analysis may be caused by water samples containing high or out of range levels of target VOCs,” says subcommittee vice-chairman Norm Kirshen, a chemist from Martinez, Calif. “The result is downtime and extensive cleanup of affected systems.

“This new screening practice, based on a method originally developed at Lancaster Labs in Lancaster, Pa.,” he says, “employs headspace SPME to extract VOCs of interest from water. Water is added to 2 mL vials containing NaCl [sodium chloride] and surrogate standard. After the sample is mixed, the vial headspace is exposed to the SPME fiber for a few seconds. The fiber is then desorbed in the heated injection port of a gas chromatograph fitted with a flame ionization detector and the resulting analytes chromatographed on a short narrow bore capillary column.

“The total analysis time is approximately three minutes,” he notes. “The concentrations of the target VOCs in the water samples are then estimated to determine whether the original water sample may be analyzed directly or may require dilution prior to purge-and-trap or headspace analysis.”

For further technical information, contact Kirshen, Martinez, Calif. (phone: 925/228-8472). ASTM Committee D19 on Water meets Jan. 25-29 in Cocoa Beach, Fla. For membership or meeting details, contact Leonard Morrissey, Jr., manager, Technical Committee Operations, ASTM International (phone: 610/832-9719). //

Copyright 2003, ASTM