Development and validation of a qNMR method for the simultaneous quantification of creatine and taurine in sports supplements.

Creatine and taurine are frequently found together in sports supplements due to their performance-enhancing and metabolic benefits. However, discrepancies between label claims and actual content have raised concerns about product quality, regulatory compliance, and possible health impacts. Accurate quantification of these compounds is therefore essential. Liquid chromatography mass spectrometry (LC-MS/MS) is widely used for its ability to detect and quantify compounds with high sensitivity and specificity. Therefore, in a previous study, an LC-MS/MS method was developed and validated for the simultaneous quantification of creatine and taurine in sports supplements. While accurate and sensitive, its somewhat cumbersome sample preparation step makes it less suitable for a commercial setting, where typically large numbers of samples must be analysed for quality control purposes. In this study, we report the first application of quantitative nuclear magnetic resonance (qNMR) for the simultaneous quantification of creatine and taurine in sports supplements, offering a simpler alternative for quality control. A qNMR method was developed, validated, and applied to commercial sports supplements, and the results were compared to label claims. All validation parameters fell well within acceptable limits, and sample analysis revealed deviations from label claims of up to +65.97% for creatine and +141.52% for taurine. Batch-to-batch variation of the products showed better consistency with variability only as high as 8.49%. Overall, this study confirms qNMR as a reliable method demonstrating specificity, precision, accuracy, and suitability for quantitative analysis. Although high-field NMR systems remain more commonly used, the method developed here is directly transferable to modern cryogen-free benchtop NMR instruments. Benchtop NMR significantly reduces operational costs and complexity, and may arguably become a valuable, reliable, and affordable tool in quality control laboratories.