Holiday notice: We will be off for the Chinese Lunar New Year Holiday between Feb 13th and 23th. Responses may be delayed. Welch US and India operate normally.
When you encounter "Not Detected" in analytical chemistry, does it truly mean the substance is absent? In practice, unscrupulous manufacturers may try to evade detection of prohibited additives by modifying molecular structures to something out of the detection scope. In this article, the author introduces a method using TOF-IDA/MS to effectively expose such modification without the need of reference standards.
![[Readers Insight] Is](//www.welch-us.com/cdn/shop/articles/1080-3182_2579cff7-26a7-4813-bab4-560f24b5e3be_535x.jpg?v=1773819396)
![[Readers Insight] Is "Not Detected" Truly "Not Detected"? (Not An Article about LOD)](//www.welch-us.com/cdn/shop/articles/1080-3182_2579cff7-26a7-4813-bab4-560f24b5e3be_345x345@2x.jpg?v=1773819396)
![[Readers Insight] Is](http://www.welch-us.com/cdn/shop/articles/1080-3182_2579cff7-26a7-4813-bab4-560f24b5e3be_535x.jpg?v=1773819396)
![[Readers Insight] Is "Not Detected" Truly "Not Detected"? (Not An Article about LOD)](http://www.welch-us.com/cdn/shop/articles/1080-3182_2579cff7-26a7-4813-bab4-560f24b5e3be_345x345@2x.jpg?v=1773819396)