Determination of volatile organic compounds in water by solid phase microextraction and infrared spectroscopy

A simple method is described combining solid phase microextraction (SPME) and infrared (IR) spectroscopy for determining volatile organic compounds (VOCs) in water. The solid phase consists of a small square of Parafilm (130 mu m thick) that is used to selectively extract the VOCs from the water. Infrared transmission spectroscopy is used to detect the extracted VOCs directly in the Parafilm. Ten VOCs (e.g., benzene, chlorobenzene, toluene, chloroform, and p-chlorotoluene) are chosen to evaluate the SPME-IR procedure. Preliminary experiments show that detection limits are in the 66 ppb-1.3 ppm range for spiked solutions, and linear dynamic calibration ranges extend nearly to the water solubility limits for all VOCs examined. Although the formal equilibration times are determined to be 30-200 min for these VOCs, we demonstrate that reproducible extractions can also be performed at 30 min. The application of SPME-IR to a real water sample shows no significant matrix interferences. Finally, the potential for determining individual compounds in mixtures is investigated by extracting aromatic components from Water samples contaminated with gasoline.