Related Experiment Video
Updated: Jun 15, 2026

Quantitative 31P NMR Analysis of Lignins and Tannins
Published on: August 2, 2021
Survey and qualification of internal standards for quantification by 1H NMR spectroscopy
Torgny Rundlöf1, Marie Mathiasson, Somer Bekiroglu
1Medical Products Agency, P.O. Box 26, SE-75103 Uppsala, Sweden. torgny.rundlof@mpa.se
Abstract:
In quantitative NMR (qNMR) selection of an appropriate internal standard proves to be crucial. In this study, 25 candidate compounds considered to be potent internal standards were investigated with respect to the ability of providing unique signal chemical shifts, purity, solubility, and ease of use. The (1)H chemical shift (delta) values, assignments, multiplicities and number of protons (for each signal), appropriateness (as to be used as internal standards) in four different deuterated solvents (D(2)O, DMSO-d(6), CD(3)OD, CDCl(3)) were studied. Taking into account the properties of these 25 internal standards, the most versatile eight compounds (2,4,6-triiodophenol, 1,3,5-trichloro-2-nitrobenzene, 3,4,5-trichloropyridine, dimethyl terephthalate, 1,4-dinitrobenzene, 2,3,5-triiodobenzoic acid, maleic acid and fumaric acid) were qualified using both differential scanning calorimetry (DSC) and NMR spectroscopy employing highly pure acetanilide as the reference standard. The data from these two methods were compared as well as utilized in the quality assessment of the compounds as internal standards. Finally, the selected internal standards were tested and evaluated in a real case of quantitative NMR analysis of a paracetamol pharmaceutical product.
Related Concept Videos
2D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)
Chemical Shift: Internal References and Solvent Effects
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
¹H NMR: Interpreting Distorted and Overlapping Signals
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule
2D NMR: Overview of Heteronuclear Correlation Techniques
¹H NMR Signal Integration: Overview

