Evaluation and application of a positively-charged phenylaminopropyl bonded stationary phase for separation of basic compounds.

Silica-based positively-charged stationary phase bonding phenylaminopropyl (named PHN) was found to produce symmetrical peak shape and higher sample loading for basic compounds. In this work, firstly, surface charge property of the PHN was evaluated by ζ-potential and retention of NO3-. A considerable amount of pH-dependent positive charges was confirmed more than that on CSH Phenyl-Hexyl, a commercial positively-charged phenyl stationary phase. Then chromatographic evaluation of standard alkaloids revealed that PHN could offer better peak shape and higher column efficiency at lower pH, and it functioned well under a wide range of buffer ionic strength. The PHN also showed different selectivity for basic compounds compared to the CSH Phenyl-Hexyl. Furthermore, it provided superior peak shape for high sample mass, demonstrating potential applications of this stationary phase in a preparative scale. These results can be explained by the strong charge intensity of the PHN stationary phase. Finally, the PHN was applied to separate a fraction from rhizomes of Corydalis decumbens, and purify dehydrocorybulbine from Corydalis yanhusuo W.T. Wang. Our study indicated the advantages and potential applications of the phenylaminopropyl bonded PHN stationary phase for basic compound separation.

Formation and conversion of characteristic volatile compounds in grilled eel (Astroconger myriaster) during different processing steps.

The aroma of grilled eel is affected by three key processing steps: curing, steaming, and grilling. This study was aimed at the determination of the difference between the characteristic volatiles in each processing stage and their influence on the final aroma of grilled eel. A total of 92 volatile compounds were identified by purge and trap (P&T) combined with gas chromatography-mass spectrometry (GC-MS) throughout the processing. Alcohol, ketone, aromatic compounds and methylated compounds were the most important volatiles in the eel meat during processing. Pyrazine was generated gradually during the entire process, and 2,3-dimethylpyrazine was only found in the sample after grilling. Distinct odors among the raw and treated samples could be indirectly distinguished according to their volatile compounds, analyzed by heatmap. Together, these results indicate a relationship between the final aroma and the whole processing. The odor coding made from the odor activity value (OAV) could be as a reference benchmark for the grilled eel product.