Sensory GC analysis of decaying vegetation and septic odors

Abstract

GC–MS is combined with sensory GC analysis to identify chemicals responsible for decaying vegetation and septic odors in drinking water supplies.A study was undertaken to identify the chemicals responsible for septic and decaying vegetation odors, not only in odor reference standards but also in natural waters. Two complementary extraction methods—closed‐loop stripping analysis and simultaneous distillation extraction—were used. Chemical identification was performed by gas chromatography (GC) with mass spectrometry, and sensory identification was accomplished by flavor profile analysis and sensory GC. Dimethyl disulfide, dimethyl trisulfide, and 2‐isobutyl‐3‐methoxypyrazine were the principal contributors to decaying vegetation odors, whereas dimethyl trisulfide and indole were strongly associated with septic odors. In addition, the study confirmed the presence of these chemicals as well as 2‐isopropyl‐3‐methoxypyrazine (associated with decaying vegetation) in water supplies.