I'm reading about a reaction from a 1970s organic chemistry book. It references A. R. sodium nitrite. What does the A. R. mean?

I see from online that "Ar" means aromatic ring. Is that the same thing?

But I've also seen "Sodium Nitrite, Granular, AR®" with a registered trademark, implying it might be a specific brand of Sodium Nitrite, but that didn't make sense. https://www.chemical.net/sodium-nitrite-acs

Are there different types of sodium nitrite?

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    $\begingroup$ Can it stand for Analytical Reagent, an equivalent to P.A. ( Per Analysis ), as the substance purity level ? $\endgroup$
    – Poutnik
    Commented Sep 16, 2020 at 9:53
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    $\begingroup$ A.R. probably Analytic Reagent as a mark of purity. Maybe later on it became a trade mark. $\endgroup$
    – porphyrin
    Commented Sep 16, 2020 at 9:54
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    $\begingroup$ This. AR = Analytical Reagent $\endgroup$
    – Waylander
    Commented Sep 16, 2020 at 10:29

1 Answer 1


I don't know if I have completely answered, but here's my go:

AR : (ANALYTICAL REAGENT) : Reagents essential for analytical purpose and research work having high purity. If reagent meets the requirements of the American Chemical Society Committee on Analytical Reagents, it will be denoted as an AR (ACS) reagent.

Also see:

  1. https://www.researchlab.in/?product-details/grade-of-purity/
  2. https://www.avantorsciences.com/pages/en/grade-definitions#:~:text=AR%E2%80%94The%20standard%20Macron%20Fine,an%20AR%20(ACS)%20reagent.

EDIT:And note that it isn't a Analytical ring

  • $\begingroup$ Thank you very much for setting me on the right foot. I was previously leaning towards the ring thing, but didn't think it really made sense. $\endgroup$
    – GFL
    Commented Sep 16, 2020 at 17:28
  • $\begingroup$ @GFL Welcome..Anytime! $\endgroup$
    – user98921
    Commented Sep 17, 2020 at 2:41

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