An accurate and reliable analysis of trimethylamine using thermal desorption and gas chromatography-time of flight mass spectrometry

Trimethylamine (TMA) is well-known for manifesting the odor of rotting fish and urine. The analysis of TMA in environmental samples generally suffers from low reproducibility and poor sensitivity. In this study, a technique for the quantitative analysis of gas phase TMA was developed using thermal desorption (TD)-gas chromatography (GC)-time of flight mass spectrometry (TOF-MS). This new approach yielded good linearity (R²=0.9930), precision (RSE=1.59%), and high sensitivity with the method detection limit (MDL) of 51pg, i.e., detection of 0.021ppb of TMA at 1L sample (limit of detection (LOD): 5.32pg (0.002ppb). This method was tested against gas samples collected from two representative sources of TMA: (1) rotten thornback fish and (2) cat urine-soaked clay. The concentration of TMA in these samples, when analyzed after treatment at varying dilution ratios, averaged 293±29.7ppm (RSE=3.82%) and 74.1±5.78ppb (RSE=3.19%), respectively. The feasibility of this approach, when tested with TD-GC-Quadruple (Q) MS, showed a good compatibility with moderately reduced sensitivity. The results of this study demonstrated that one can achieve highly reliable and reproducible analysis of TMA from environmental samples when using thermal desorption (for pretreatment) and detection (by the TOF or Q-MS system).