Abstract
The assessment of primary calibrator purity is critical for establishing traceability to the International System of Units (SI). Recently, quantitative nuclear magnetic resonance (qNMR) has been used as a purity determination method for reference material development, and many related measurement techniques have been designed to acquire accurate and reliable results. This review introduces the recent advances in these techniques (including multidimensional methods), focusing on the application of qNMR to reference material preparation.
Highlights
The establishment of metrological traceability is important for achieving the comparability of measurement results [1]
Unlike to the mass balance method, quantitative Nuclear magnetic resonance (NMR) (qNMR) is poorly suited for the separation and Unlike to the mass balance method, qNMR is poorly suited for the separation and analysis of impurities with similar structures, as the analyte peaks of analyte may overlap analysis of impurities with similar structures, as the analyte peaks of analyte may overlap with with those those of of the the impurities
An internal standard (IS)-fortified sample solution was analyzed by liquid chromatography [45], and impurity-free fractions containing the analyte and the IS were collected into the same vial, with subsequent purity assessment performed by qNMR
Summary
The establishment of metrological traceability is important for achieving the comparability of measurement results [1]. The purity of primary calibrators has been traditionally determined by the mass balance method, that is, by subtracting the total amount of impurities from 100%, with impurity quantitation performed using techniques such as gas chromatography, liquid chromatography, thermal gravimetric analysis, and Karl Fischer titration. The mass balance method is well-established, it cannot be applied to organic substances, which lack chromophores and nonvolatiles. Quantitative NMR (qNMR) has been used for purity analysis as an alternative to the mass balance method, allowing one to determine analyte purity directly by comparison with a standard and simplify the overall purity determination procedure.
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