ABSTRACT
An LC-MS method with natural isotope abundance correction and a 1H NMR relative quantitative method were established to determine the deuterium incorporation of donafenib tosilate, a new deuterated drug molecule. First, the peak areas of isotopic impurities (non-deuterated and incompletely deuterated impurities) and deuterated drug were recorded through the single ion monitoring (SIM) mode of the established LC-MS method and then corrected in terms of the natural isotope abundance offered by ChemDraw soft, removing the nature isotope interference from 13C, 37Cl, etc. The corrected areas were subsequently used to calculate mol% of isotopologues (D0, D1, D2, D3) and Atom% D, namely, deuterium incorporation. In addition, a 1H qNMR experiment was conducted with the aromatic proton at δ 8.63 and the residual proton of isotopic impurities at δ 2.79 as quantitative peaks. The mixture of DMSO-d6 and D2O (10∶1) was employed as the solvent to change the spin-coupling between the residual proton and active hydrogen so that the residual proton could be measured as the single peak, and the sensitivity was greatly improved. The acquisition parameters were also optimized, and Atom% 1H and the deuterium incorporation were then calculated. The two methods were applied to samples of three commercial batches, and the testing results were almost consistent. Both methods proved accurate, sensitive, fast and independent of standard substances and accurate weighing, which could be applied to the determination of the deuterium incorporation of donafenib tosilate and provide a reference for other deuterated drugs.
ABSTRACT
A quantitative nuclear magnetic resonance method(qNMR) was established for determination of the absolute content of febrifugine. Proton nuclear magnetic resonance spectroscopy of febrifugine was obtained in DMSO-d₆ with hydroquinone as the internal standard substance on a Bruker Ascend 600 MHz superconducting nuclear resonance spectrometer at 298 K. The specific parameters were as follows: the observing frequency was 600 MHz,spectra width was 7 211 Hz, pulse width was 9.70 μs, pulse sequence was zg30,scan times was 32 and relaxation time was 2 s. The proton signal peaked at δ 7.71 for febrifugine and δ 6.55 for hydroquinone were selected as the quantification peaks. Linear regression of quantitative peak area ratio of febrifugine-hydroquinone versus their mass ratio yielded a correlation coefficient of 0.999 6 and a regression equation of +0.008 6．The linear range of febrifugine was 2.17-17.07 g·L⁻¹,the precision RSD was 0.78%(=6),the repeatability RSD was 1.2%(=6),and the contents of three batches of febrifugine sample were 94.91%,95.09% and 95.52%,respectively. The content of febrifugine was 96.44% determined by high performance liquid chromatography(HPLC). The relative error of the content of febrigugine determinted by qNMR and HPLC methods was 1.27%. The results showed that the internal standard method of proton nuclear magnetic resonance spectroscopy could be used to determine the absolute content of febrifugine.
Subject(s)
Magnetic Resonance Spectroscopy , Piperidines , Protons , QuinazolinesABSTRACT
The method of quantitative nuclear magnetic resonance spectroscopy (qNMR) for determination of epigoitrin in Radix Isatidis was established based on solid phase extraction (SPE).The twice ultrasonic extraction method using pure water was used for fully extracting epigoitrin in sample, and then the extraction was enriched and concentrated by poly-Sery MCX SPE cartridge.The effect of sample pretreatment and qNMR experimental conditions was investigated.The qNMR experiment conditions were selected using DMSO as solvent, calibrated 2,3,5-triiodobenzoate as internal standard, and P1(pulse width)=14.1 μs, d1(pulse delay time)=5 s, NS(number of scan)=256.The .1H-NMR peaks of δ 5.365-5.399 (H-7b, d, 1H) of epigoitrin were chosen as the quantitative peaks.Method validation was performed including precision (intra-day precision RSD was 0.5%, and the inter-day precision was 0.8%), linearity (correlation coefficient r>0.9991), LOD (0.05 mg/g, standard curve method) and LOQ (0.19 mg/g, S/N≥150).The recoveries of the SPE-qNMR were 97.4%-101.7%.The result showed that the method was stable, accurate and reliable.With this method the epigoitrin in a real Radix Isatidis was determined to be <0.19-1.26 mg/g.SPE combining with qNMR could extend the application field of qNMR, especially in the detection of low-content component in complex samples.
ABSTRACT
OBJECTIVE: To study the content determination method of crotamiton. METHODS: The quantitative mass balance method, HPLC external standard method and nuclear magnetic resonance (QNMR) were used to determine the content of crotamiton, respectively.The accuracy of the three methods was evaluated. RESULTS: The contents of crotamiton were 99.2%, 102.9% and 99.1% respectively as determined by the three different methods. CONCLUSION: Because the ultraviolet absorption coefficients of cis- and trans-crotamiton might be different, the current pharmacopoeia method, ie, using integrated peak areas to calculate the content, is questionable. QNMR method can measure the contents of cis- and trans-crotamiton respectively, so it can be a complementary method to establish the reference standard.
ABSTRACT
A quantitative nuclear magnetic resonance spectroscopic ( qNMR) method was established for the simultaneous determination of resveratrol and polydatin in Polygonum Cuspidatum traditional Chinese herb cuts and granule. The 2_step ultrasonic extraction method using 80% alcohol and acetone was used for fully extracting these two components in samples before qNMR determination. The qNMR experimental conditions were investigated and deuterated dimethyl sulphoxide_deuterium oxide (10∶1, V/V) was selected as solvent, the pulse delay time was 5 s, the scan number was 32, 2,3,5_triiodobenzoate was used as internal standard which was calibrated with primary standard substance of potassium hydrogen phthalate. The 1 H_NMR peaks atδ6. 388-6. 391 ( d, 2H) of resveratrol and δ 6. 322-6. 330 ( t, 1H) of polydatin were chosen as the quantitative peaks. Method validation was performed in terms of precision ( RSD0. 999), limit of detection (0. 23 g/L for resveratrol and 0. 24 g/L for polydatin) and limit of quantitation ( resveratrol 0. 69 g/L, polydatin 1. 57 g/L), recovery ( resveratrol 97. 7% -103 . 5%, RSD=2 . 4%, polydatin 94 . 5%-99 . 2%, RSD=1 . 6%, including the sample extraction and preparaton process) . The results showed the reliability of qNMR for traditional Chinese medicine assay. The resveratrol and polydatin in Polygonum Cuspidatum real cuts and granule samples were experimental determined as 3. 57-5. 69 mg/g and 12. 73-24. 07 mg/g, respectively.