[Release rule of volatile components of moxa sticks with increase of temperature]

To systematically investigate the changes rule of volatile oil and its main components released from moxa sticks under different headspace temperatures and combustion conditions, so as to guide the clinical rational selection of the temperature for moxa sticks.

Using the headspace gas chromatography-mass spectrometry (HS-GCMS) technique, the released gas from moxa sticks was collected at the headspace temperature (from room temperature [25 ℃] to 190 ℃) and during combustion. One mL of the gas was injected into 6890/5973N gas chromatography-mass spectrometry (GCMS). The release rates of volatile components of moxa sticks were calculated by total ion chromatography (TIC) and butanone internal standard method. The volatile components of moxa sticks were qualitatively analyzed by analyzing the mass spectra of each volatile component and matching the Nist 14 standard mass spectrometry library. By comparing and analyzing the peak intensity changes rule of 1,8-cineole and its main harmful components (benzene, toluene and phenol) under different headspace temperatures and combustion conditions, the optimal temperature for clinical use of moxa sticks was found.

At room temperature and 50 ℃, the release rate of volatile components from moxa sticks was very low, and it showed a significant increase trend with the increase of temperature. When the headspace temperature was 190 ℃, the release rate of volatile components from moxa sticks reached 0.864 2%, which was 2 161 times as same as that at room temperature. After combustion, it dropped sharply to 0.027 9%, which was 96.8% lower than that at the headspace temperature of 190 ℃. When the headspace temperature was 125 ℃ and 150 ℃, the content of 1,8-cineole, a typical beneficial component in the volatile components of moxa sticks, was the highest. When the headspace temperature was higher than 150 ℃, its content showed a significant downward trend. Under combustion conditions, a large number of harmful substances, such as benzene, toluene and phenol, were detected.

The combustion condition is not conducive to the efficient utilization of the volatile oil of moxa sticks. Temperature of 125-150 ℃ is the best for releasing the volatile components of moxa sticks, which is not only conducive to the release of the beneficial volatile components of moxa sticks, but also can greatly inhibit the production of harmful components.