Nitrite Detection at Picogram Level, is it possible?

“While ion chromatography is the primary method for nitrite ion analysis, employing the Griess reaction offers several advantages over it. This includes faster and easily visible responses, as well as greater flexibility in sample preparation using organic solvents.” This is asserted by Junyong Jo.

Inspired by Griess reagents, he developed a series of molecular probes designed to undergo intramolecular cyclization when reacting with nitrite ions to form diazonium (Rapid-Response Nitrite Probes: Intramolecular Griess Reaction for Nitrite Detection at Picogram Level). This probe not only induces striking color changes but also enables turn-on fluorescence, serving as an alternative detection method for nitrite analysis:

He further evaluated this method on common drug excipients such as microcrystalline cellulose and dicalcium phosphate dihydrate. The results demonstrated its applicability and robustness.


This innovative approach surpasses ion chromatography in terms of solvent compatibility and provides dual detection options with exceptionally low limits of detection.

This advancement invites critical discussion and has the potential to reshape how we approach nitrite ion analysis in drug products. Do you agree?


I haven’t purchased and read the full paper yet (I will be), but a few things spring to mind.

I love the pushing of boundaries and the science to get ever more sensitive techniques. But do we need it? For materials like MCC, the levels present currently are much higher than picogram level, and unless there is some significant change in the manufacturing process for MCC in the near future it is unlikely that we are ever going to be needing to measure down to that level for materials of this type. There may be applications for materials that are currently testing to levels of <LOQ or <LOD for the techniques being currently utilized, but do these materials, with these low levels, contribute significantly to the nitrosamine levels formed (hypothetical question - the answer could be yes, depending on the formulation and dose format etc.).

There are more and more techniques becoming available for the quantification of nitrites in raw materials, with the potential for lower and lower LOQs, but how robust are these techniques? How much impact does sample prep have? There is a piece of work crying out to be done there, by someone who has the capability to do all techniques, to compare, contrast and critique them all, on one material. Even then, are any of the techniques suitable for all materials?


Great thanks for sharing!!

I could not access the articel but it sounds awesome - thats me saying as an Analytical Chemist working mainly with GC or HPLC methods

Such techniques are, to my humble opinion, elegant, even though some work still needs to be done. It has the advantage not needing complex analytical methods and could be conducted in QC labs to check quality of material.

Of course further questions arise:
Can be all excipients tested with such a method or are there restriction?
Is such an approach accepted by authorities?

I would love to see more of such approaches, as it takes out the complexity and provides fast results


Really wonderful process. My major concern all these days have been that people are focussing a lot on the nitrosamines but not on the nitrite. Good to see such a sensitive technique. Just that hopefully we do not need to know about pico levels of nitriteb :smiley:


These sensitive techniques are interesting in a theoretical way (it’s fun to see how far analytical chemistry goes). But on a practical level I think they will never be applied to our industry. I imagine my factory as a control in process…
At the manufacturing level it is crazy to look for picograms.
But even more so, putting a nitrite-free medication on the market that a patient will take with his food… ( Hot dog for example…) Perhaps we will see instructions on the leaflet not to eat it with processed food (full of nitrite salts for preservation…)
We are entering a new madness… Someone from regulation shows some sense.

Finally, where I would like to see more control is in raw materials and excipients. I think it can be greatly improved. I give as an example meglumine… which in detergents they already knew since the 90s formed nitrosamines… and ethanolamines…
Also nitrosatable amines or substances such as piperazine that remains as an impurity in some API… :slightly_smiling_face: