Application of quantitative NMR in pharmaceutical analysis: Method qualification and potency determination for two...

Quantitative NMR (qNMR), being a well-established analytical tool featuring efficiency, simplicity as well as versatility, has been extensively employed in pharmaceutical and medicinal testing. In this study, two ¹H qNMR methods were developed to determine the %wt/wt potency of two new chemical entities (compound A and compound B) used in early clinical phase process chemistry and formulation development. The qNMR methods were demonstrated to be significantly more sustainable and efficient than the LC-based approach by substantially reducing the cost, hands-on-time, and materials consumed for testing. The qNMR methods were achieved on a 400 MHz NMR spectrometer equipped with 5 mm BBO S1 broad band room temperature probe. The methods with CDCl₃ (for compound A) and DMSO-d₆ (compound B) as solvent as well as commercially certified standards for quantitation were phase-appropriately qualified in terms of specificity, accuracy, repeatability/precision, linearity, and range. Both qNMR methods were demonstrated to be linear over the range of 0.8-1.2 mg/mL (80% to 120% of the nominal sample concentration of 1.0 mg/mL) with a correlation coefficient greater than 0.995. The methods were also demonstrated to be accurate with average recoveries ranging from 98.8% to 98.9% and 99.4-99.9% for compound A and compound B respectively as well as precise with %RSD of 0.46% and 0.33% for compound A and compound B respectively. The potency results of compound A and compound B determined by qNMR were compared with those determined by the conventional LC-based method and the qNMR results were demonstrated to be consistent with the LC-based method with absolute difference of 0.4% and 0.5% for compound A and B respectively.