Recent Advances in Pretreatment and Detection Technologies for Earthy Odorants in Water Systems

Earthy odorants (such as geosmin, 2-methylisoborneol, pyrazines, etc.) are primary contributors to musty-earthy off-flavors in drinking water and aquatic products. These compounds exhibit odor thresholds as low as sub-ng/L and occur at trace concentrations in complex environmental matrices including surface water, sediments, algae-rich waters, and biological tissues, presenting substantial challenges for accurate quantification and regulatory compliance. This review systematically evaluates advances in sample pretreatment and analytical techniques for earthy odorants over the past decade. Recent developments in pretreatment emphasize miniaturization and automation of microextraction techniques-such as solid-phase microextraction and liquid-phase microextraction-alongside integration of novel functional materials including metal-organic framework-derived porous carbons and dummy-template molecularly imprinted polymers to enhance extraction selectivity. Gas chromatography-mass spectrometry remains the established technique for quantification, while comprehensive two-dimensional gas chromatography and ion mobility spectrometry offer enhanced separation and identification capabilities. Emerging sensor platforms (e.g., biosensors, surface-enhanced Raman spectroscopy) provide promising alternatives for rapid on-site screening. Current challenges-including matrix interference, absence of standardized protocols, and limited consideration of enantiomeric differentiation-are examined, and future directions toward integrated, automated, and field-deployable analytical systems are discussed. This review aims to support development of robust, green analytical workflows for routine earthy odorants monitoring, ultimately contributing to improved water quality management.