. 2021 Oct 19;26(20):6308. doi: 10.3390/molecules26206308
© 2021 by the authors.
Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Figure 2.
Internal standard and external standard method.