Optimization of Electrospray Ionization for Liquid Chromatography Time-of-Flight Mass Spectrometry Analysis of Preservatives in Wood Leachate Matrix

Abstract

Triazoles and 3-iodo-2-propynyl butylcarbamate (IPBC) are commonly used wood preservatives active against a wide range of fungi and bacteria. As they are prone to leaching, their amounts need to be monitored by the industry to determine preservative loss from the products and for environmental impact assessment. Therefore, a liquid chromatography–electrospray–time-of-flight mass spectrometry (LC–ESI–TOFMS) method was developed and optimized for simultaneous quantification of triazoles and IPBC in aqueous wood extracts, specifically wood leachate. Analyte pre-concentration on a solid-phase extraction cartridge prior to the analysis yielded > 94% recoveries. ESI method parameters (e.g., solvent system, electrolyte type, electrolyte concentration, capillary and fragmentor voltages) were selected based on an initial screening followed by an in-depth optimization via design of experiments. The optimal conditions employed an acetonitrile-water solvent system with 1.7 mM ammonium acetate, capillary voltage of 4350 V, and fragmentor voltage of 115 V. The developed method was applied to industrial wood leachate samples and the matrix-affected limits of detection were found to be 1.2–1.5 µg L−1 with interlay repeatability being < 7%.