At the time being, the JECFA specification is the quality index for stevia products. For new food additives such as stevia, JECFA cannot cover all important quality aspects in the first line.

In addition to the parameters listed in the JECFA specification, many more items as shown below should be paid attention to when looking for stevia products with premium quality.

	Standard Chromadex	EPC sample	Others
Labeled HPLC area%	97.60%	99.17%	99.01%
Labeled Water content	4.24%	1.54%	none
Water content (K-F method)	4.4%	1.54%	3.9%
Real Reb A content	93.31%	97.67%	93.9%

As seen above there are a big differences in content and purity between the labeled and the actual value.
The difference came from several aspects as below:    
1) How to measure water content
Loss on drying  VS  Karl Fischer Moisture Titration
Water content measured by loss on drying is lower than actual value. K-F method is more accurate.
2) How to use reference standard
For the reference standard from Chromadex, it’s recommended to measure water content by K-F method and re-calculate adjusted purity based on HPLC area.

Suggestion: Choosing manufacturers who has strict QC system and knows the right analytical method.