We report a comprehensive analysis of the acquisition-related sources of uncertainty for internally and externally standardized qNMR experiments. The impacts of major instrument- and sample-related sources of biases and uncertainties are quantified where possible, and the validity of correction and calibration techniques are also discussed. The application of uncertainty budgets for qNMR is well established for simple, internally standardized systems, but the model is incomplete and does not allow for the additional biases and sources of uncertainty that arise from spectrum complexity and external standardization. This report considers the additional contributions to the uncertainty budget that need to be considered to ensure SI traceability of measurement across a wider range of analytes and NMR methodologies.
Keywords: SI traceability; bias; certified reference material; instrument uncertainty; qNMR.