Objective To establish a method using automated solid-phase microextraction-gas chromatography-tandem mass spectrometry for the determination of trace levels of 2-methylisoborneol (2-MIB) and geosmin (GSM) in drinking water.

Methods The sensitivity of the instrument was enhanced by optimizing gas chromatography conditions and mass spectrometry parameters.Various salting-out conditions, extraction temperatures, and extraction times were compared to identify the optimal pretreatment and solid-phase microextraction conditions.The performance was evaluated based on spiked recovery, precision, limit of detection, and limit of quantification.

Results The established method enabled the accurate determination of trace 2-MIB and GSM in 5 mL drinking water samples.The method demonstrated excellent linearity for both 2-MIB and GSM within the concentration range of 2.0 to 100 ng/L, with correlation coefficients (r) exceeding 0.999.The limits of detection for 2-MIB and GSM were 0.56 and 0.71 ng/L, respectively, and their limits of quantitation were 1.84 and 2.36 ng/L, respectively.The spiked recoveries ranged from 89.7% to 115% for 2-MIB and from 83.3% to 110.3% for GSM.The intra-day relative standard deviations for 2-MIB and GSM ranged from 2.4% to 3.1% and from 2.3% to 4.7%, respectively.The inter-day relative standard deviations ranged from 4.2% to 9.4% and from 3.2% to 7.5%, respectively.This method was applied to analyze five drinking water samples and both target compounds were detected.Their concentrations ranged from 1.6 to 4.6 ng/L (2-MIB) and from 2.2 to 2.5 ng/L (GSM).These concentrations were below the limit of 10 ng/L as specified in the Standards for Drinking Water Quality(GB/T 5749-2022).

Conclusion This method is simple, accurate, efficient, and highly sensitive for the determination of 2-MIB and GSM in drinking water.