Analytical and Bioanalytical Chemistry

, Volume 385, Issue 4, pp 760–765 | Cite as

Purity assessment problem in quantitative NMR—impurity resonance overlaps with monitor signal multiplets from stereoisomers

  • Frank MalzEmail author
  • Harald Jancke
Original Paper


This paper describes the situation that can emerge when the signals to be evaluated in quantitative NMR measurements—so-called “monitor signals”—consist of several resonance lines from the stereoisomers of the analyte in addition to an impurity signal underneath. The monitor signal problem is demonstrated in the purity assessment of two samples of 2-(isopropylamino)-4-(ethylamino)-6-chloro-1,3,5-triazine (atrazine), a common herbizide which served as analyte in a CCQM intercomparison. It is shown that, in DMSO-d6 solution, a mixture of stereoisomers leads to several individual overlapping singlets, which are further split by spin–spin coupling. A measurement protocol was developed for finding and identifying an impurity that has a signal that is positioned precisely beneath the methyl signal chosen as the monitor signal in one of the samples. Quantitative NMR purity assessment is still possible in this special case, but with higher uncertainty.


Quantitative NMR Monitor signal Impurities Atrazine Purity assessment 



Financial support by the Federal Ministry of Economics and Labour (BMWA) (AiF project: 13843 N/1), the German Federation of Industrial Cooperative Research Associations “Otto von Guericke” (AiF) and the German Research Association of Medicine Manufacturers (FAH) is gratefully acknowledged. Furthermore, we thank the referees for helpful suggestions.

Supplementary material

216_2006_415_MOESM1_ESM.pdf (117 kb)
Purity assessment problem in quantitative NMR – overlapping impurity resonance with monitor signal multipletts due to stereoisomers (PDF 119 kb)


  1. 1.
    Milton MJT, Quinn TJ (2001) Metrologia 38:289–296CrossRefGoogle Scholar
  2. 2.
    Jancke H (1998) CCQM Rep 98:1–12Google Scholar
  3. 3.
    Jancke H (1998) Nachr Chem Tech Lab 46:720–722Google Scholar
  4. 4.
    Jancke H, Malz F, Haesselbarth W (2005) Accred Qual Assur 10:421–429Google Scholar
  5. 5.
    Kasler F (1973) Quantitative analysis by NMR spectroscopy. Academic, LondonGoogle Scholar
  6. 6.
    Freeman R (1988) A handbook of nuclear magnetic resonance. Longman Scientific, Harlow, UKGoogle Scholar
  7. 7.
    Malz F, Jancke H (2005) J Pharm Biomed Anal 38:813–823Google Scholar
  8. 8.
    Al Deen T, Hibbert DB, Hook JM, Wells RJ (2004) Accred Qual Assur 9:55–63Google Scholar
  9. 9.
    Reck G, Kircheis A, Bauwe R (1982) Cryst Struct Chem 11:1997Google Scholar

Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  1. 1.Federal Institute for Materials Research and Testing (BAM)BerlinGermany

Personalised recommendations