The fabrication and experimental test results were presented for a micro-electro-mechanical systems (MEMS)-based gas chromatography column. Compared with conventional column, this micro-gas chromatography column is suitable for on-line analysis and monitoring because of the small size, rapid analysis and other characteristics. These 0.5, 1 and 3 m GC columns were fabricated using a deep reactive-ion etching (DRIE) and were coated the stationary phase via a dynamic coating procedure. These GC columns perfectly separated the mixture of benzene, toluene and o-xylene in less than 200 s, where, the 3.0 m of the GC column achieved) a high resolution of 14.3 between toluene and o-xylene and yielded approximately 6160 plates. Moreover, the effect of separation performance for different column length were examined and compared. These GC columns are suitable for the application of a variety of disciplines, including environmental analysis, methane gas probes and homeland security.

In this study, we developed a qualitative analytical method based on liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UHPLC-Q-TOF-MS/MS) for identification of multi-constituents of raw Fructus Arctii (RFA) and processed Fructus Arctii (PFA). We established a UHPLC-UV analytical method for simultaneously determining 6 major compounds in Fructus Arctii. UHPLC- Q-TOF-MS/MS qualitative analysis was performed under negative and positive ion modes and a total of 23 chemical compounds were identified. The analysis data were subjected to a principle component analysis with a t-test. Ten peaks were found to be the main difference (P<0.05) between RFA and PFA. HPLC-UV quantitative method result showed the contents of 6 constituents were different between RFA and PFA. The results indicated that there was less arctiin, chlorogenic acid, isochlorogenic acid A in PFA than in RFA. However, there were higher levels of arctigenin, isochlorogenic acid B, isochlorogenic acid C in the PFA than RFA, which may be the main reason for different clinical efficacy of RFA and PFA.