Accurate mass determinations for the confirmation and identification of organic microcontaminants in surface water using on-line solid-phase extraction liquid chromatography electrospray orthogonal-acceleration time-of-flight mass spectrometry.

The identification of polar microcontaminants in surface water is an important issue in environmental analysis. Liquid chromatography/mass spectrometry (LC/MS) is frequently applied for this purpose. However, even in combination with tandem mass spectrometry (MS/MS), unambiguous identification of the compounds detected is often difficult. The potential of an alternative strategy, based on the ability of an orthogonal-acceleration time-of-flight mass spectrometer to routinely perform accurate mass determination at 10 ppm in on-line LC/MS, is explored. On-line solid-phase extraction LC electrospray orthogonal-acceleration time-of-flight mass spectrometry is shown to enable the determination of pesticides from various compound classes in surface water in the concentration range of 0.1 to 10 µg/L. In addition, the ability to discriminate and unambiguously identify pesticides in mixtures of isobaric and/or isomeric compounds is investigated. Copyright © 1999 John Wiley & Sons, Ltd.