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Application of qNMR. Part 2:Quantification of carminic acid in cochineal extract


NMR spectroscopy, in principle, counts the number of atoms in molecules, and so the purity of the sample can be quantified from the ratio of the signal intensities of a target material and a reference. Quantitative NMR (qNMR) is widely applicable because the target materal is not used as a standard sample of known purity. This Note introduces an example of qNMR analysis for carminic acid in cochineal extract, the standard sample of which is not easily available.
Carminic acid
Carminic acid
Carminic acid is a main component of cochineal extract,
originally obtained by drying scale insects and
extracting them with ethanol or water.

The purity of test reagents of carminic acid and
that of food additives of cochineal extract are
examined by qNMR.

Fig.1 qNMR spectrum of carmic acid
(Spectrometer: JNM-ECA600)

Table Summary of sample information and results of qNMR analyses
Summary of sample information and results of qNMR analyses

Correlation beween qNMR purity and LC peak area
Fig.2 Correlation beween qNMR purity and LC peak area


  1. Purities of carminic acid in reagents and cochineal extracts were determined by qNMR.
  2. Purities from qNMR were confirmed to have strong correlation with LC peak area.

⇒It was found that qNMR is a useful quanti-fication analysis for natural products, for which standard samples for quantification are not available.


N.Sugimoto, A.Tada, T. Suematsu et al. Food Hyg.Saf.Sci.,2010, 51,19-27


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