Detection of Trimethylamine Based on a Manganese Tetraphenylporphyrin Optical Waveguide Sensing Element.

The sensitive detection of trimethylamine has been accomplished by using a homogeneous optical waveguide sensor system. Also the sensor can be easily fabricated by using tetraphenylporphyrin manganese (MnTPP) as sensitive materials to detect different volatile organic compounds (VOC). NMR (1H-NMR), field-emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS), infrared (IR), and ultraviolet-visible (UV-vis) instrumental means were used to characterize its structure. Gas-sensing measurements indicated that the sensing element has shown good selectivity, high sensitivity and a low detection limit level of 0.1 ppm to trimethylamine (TMA) with the presence of interference gases at room temperature. For a range of trimethylamine concentrations from 0.1 to 1000 ppm, the sensor has shown a short response time. Also the response time and recovery time are 1.5 and 50 s, respectively. Simulation experiments (dichloromethane, chloroform and carbon tetrachloride were selected as interference gases) showed little interference with its gas sensing. That may provide an ideal candidate for detecting the freshness of fish and seafood.