**4. Conclusions**

The current study endeavors to establish the comprehensive profiles and quality standards of avocado oil. The "solvent-free" SFE method used for avocado oil extraction is highly recommended in the food industry. Two independent and complementary analytical methods (LC and GC) were used to investigate different classes of compounds (TG and FA) in avocado oils. Characterization and quantitative analysis of 13 TGs in oils extracted from different parts of avocado fruit, viz. peel, pulp and seed, were conducted using UHPLC/ESI-MS. The complex TGs can be conclusively identified using the MS detection with the correct attribution of the acyl in the sn-2 position, as well as the calculation of ISYs for ions formed in the IS-CID. The efficiency and accuracy of the quantification were improved by the selection of one single reference standard from the same ECN group when reference standards are commercially unavailable. The FA compositions yielded from GC/MS method were in good agreement with UHPLC/MS. Although chemical profiles of avocado pulp and peel were very similar, a significant difference was observed for the avocado seed. It is concluded that the combination of TG and FA analysis using UHPLC/ESI-MS and GC/MS, as well as multivariate statistical analysis may provide comprehensive information for the characterization, standardization and authentication of avocado oils. The reported techniques might be useful for assessing the quality of other plant oils.

**Supplementary Materials:** The following are available online: Table S1: Information of commercial avocado (*P. americana*) oils.

**Author Contributions:** M.W. and P.Y.: chemical analysis, data analysis and manuscript preparation; A.G.C.: study design and manuscript preparation; D.C.: sample extraction and measurement of physicochemical properties; J.Z.: statistical analysis and manuscript editing; B.A. and Y.-H.W.: data interpretation and manuscript editing; I.A.K.: manuscript final version approval and guarantee the integrity of the entire study. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research is supported in part by "Science Based Authentication of Dietary Supplements" funded by the Food and Drug Administration grant number 1U01FD004246-05, and the United States Department of Agriculture, Agricultural Research Service, Specific Cooperative Agreement No. 58-6060-6-015.

**Acknowledgments:** We would like to thank Jon F. Parcher and Iffat Parveen for manuscript editing, proof-reading and valuable suggestions.

**Conflicts of Interest:** The authors declare no conflict of interest.
