Direct Comparison of¹⁹F qNMR and¹H qNMR by Characterizing Atorvastatin Calcium Content

Abstract

Quantitative nuclear magnetic resonance (qNMR) is a powerful tool in measuring drug content because of its high speed, sensitivity, and precision. Most of the reports were based on proton qNMR (1H qNMR) and only a few fluorine qNMR (19F qNMR) were reported. No research has been conducted to directly compare the advantage and disadvantage between these two methods. In the present study, both 19F and 1H qNMR were performed to characterize the content of atorvastatin calcium with the same internal standard. Linearity, precision, and results from two methods were compared. Results showed that 19F qNMR has similar precision and sensitivity to 1H qNMR. Both methods generate similar results compared to mass balance method. Major advantage from 19F qNMR is that the analyte signal is with less or no interference from impurities. 19F qNMR is an excellent approach to quantify fluorine-containing analytes.

Ecofriendly Viscoelastic Solutions Formed from a Recyclable Rosin-Based Amine Oxide Surfactant

“…Recovery rate is an important parameter to evaluate the efficiency of a recovery process. For ensuring accuracy, the qNMR method, which is often used in the identification and quantification of drugs and biological metabolites, was used to detect the residual R-11-3-AO in the supernatant. , Maleic acid was selected as the internal standard because its 1 H NMR signals do not overlap with those of R-11-3-AO . Comparing the absorption peak intensities of maleic acid and R-11-3-AO , the relative quantitative method was used to calculate the surfactant content in the supernatant as follows: P % = A x N MAH A MAH N x × m MAH M MAH × 1 n x × 100 % R % = 1 − P % where A x and A MAH are the integral values of the characteristic peak signals of R-11-3-AO and maleic acid, respectively; N x and N MAH are the hydrogen numbers corresponding to the characteristic peaks of R-11-3-AO and maleic acid, respectively; m MAH is the mass of maleic acid, and M MAH is the molecular weight of maleic acid; n x is the original number of moles of R-11-3-AO .…”

“…For ensuring accuracy, the qNMR method, which is often used in the identification and quantification of drugs and biological metabolites, was used to detect the residual R-11-3-AO in the supernatant. 57,58 Maleic acid was selected as the internal standard because its 1 H NMR signals do not overlap with those of R-11-3-AO. Comparing the absorption peak intensities of maleic acid and R-11-3-AO, the relative quantitative method was used to calculate the surfactant content in the supernatant as follows:…”

A screening method for the quantitative determination of selective androgen receptor modulators (SARMs) in capsules by high resolution 19F- and 1H-NMR spectroscopy

“…These settings ensured equal excitation of all the uorine nuclei. 29,30 The relaxation time T 1 was determined using a t1ir1d pulse program and resulted in no longer than 1.4 s for all uorinated compounds including 2,4-DCBTF. A relaxation delay of seven times the duration of the longest T 1 (D 1 = 7 × T 1 ) was applied to obtain 99.9% signal recovery.…”

Internal Standard Reference Data for 19F qNMR: 3,5-Bis(trifluoromethyl)Benzoic Acid [ISRD-09]

“…There are a number of literature reports on the use of specific compounds as 19 F qNMR internal standards. 25,[29][30][31] The focus of these papers are generally a specific application of 19 F qNMR rather the general application of an individual compound as a higher-order, SI-traceable primary measurement standard for qNMR. The second goal of this report is to establish the desirable properties for individual compounds to serve as versatile SI-traceable internal standards for purity assignment by 19 F qNMR.…”