A Versatile Method for Determination of Resin Acids in Occupational Softwood Sawmill Dust Samples by Liquid Chromatography‐Atmospheric Pressure Chemical Ionization‐Mass Spectrometry

ABSTRACT

Occupational exposure to softwood dust has been linked to upper and lower respiratory symptoms, eye irritation, contact dermatitis, and an elevated risk of sino‐nasal cancer. Resin acids, naturally occurring extractives that vary by tree species, are suspected contributors to these health effects, yet existing analytical methods have struggled to resolve key isomeric acids. This study aimed to develop a rapid, robust, sensitive, and selective liquid chromatography‐mass spectrometry (LC‐MS) method for the determination of individual resin acids in personal wood dust samples from Norwegian sawmills. Six commercially available reversed‐phase columns and multiple mobile phase systems were evaluated for chromatographic performance. Optimal separation was achieved with a C18‐amide column (150 × 2.1 mm, 3 µm) using an isocratic mobile phase of acetonitrile and 30 mM ammonium acetate at pH 6.30, 0.3 mL min ⁻¹ with a 15‐min runtime. Optimal detection employed atmospheric pressure chemical ionization (APCI) in negative mode. This method was applied to six personal sawmill dust extracts, enabling determination of five resin acids (abietic acid, dehydroabietic acid, levopimaric acid, and the coeluting isopimaric and pimaric acids) and one oxidation product (7‐oxodehydroabietic acid). The LC‐APCI‐MS method improves separation of resin acids over prior LC approaches, with minimal sample preparation, and is suitable for routine monitoring of occupational exposure to resin acids in wood dust.