System Performance Affecting Quantitative NMR Data: S/N and Resolution
Fig. 1: S/N and repeated integral accuracy (SD)
Fig. 1 shows the S/N and the accuracy of its integral value (SD: Standard deviation) that are theoretically calculated.The SD is the result of integration repeated 100 times. The figure shows that the integral accuracy is heavily dependent on the S/N; for example, an integral accuracy of 1% or less requires an S/N of 100 or more.
The S/N also affects resolution. Fig. 2 shows the results of qNMR experiments. The S/N of BTMSB, a standard for quantitative analysis, is reduced to 1/3 when resolution is low.
If signals having a low S/N are selected for quantitative analysis, resolution alone can significantly affect the results of analysis.
Fig. 2: S/N vs. resolution qNMR sample:Analyte: vinclozolin; quantitative reference: 1,4-BTMSBd6 deuterated DMSO solution
Quantitative NMR: Frequently asked questions
- How accurate is quantitative data going to be in my NMR system?
- Does my NMR system continue to maintain its performance level?
- Why is the data different this time? Is my system operating at peak performance?
Daily System Checkup for Quantitative NMR AnalysisOperating procedure
- The same sample is used for each experiment.
- The analyte and reference are loaded.
- The analyte and reference are reliable including SI traceability.
- The sample is a stable solution.
- 2.Analytical process
- The measurement method is validated.
- 3.Analytical results (according to the system compatibility guidance in Japanese Pharmacopoeia)
- 3 samples: Repeat analysis 3 times or 6 times
- Detection: S/N > 100
- System compatibility: Molecular integral ratio < 1
- System reproducibility: Relative standard deviation in area ratio < 1 %
JEOL provides quantitative NMR menus for system diagnosis and periodical inspection.
Contact your local representative for details.