Introduction Despite significant advances in analytical methods, the quality evaluation and adulteration detection of chemically complex traditional Chinese medicines continues to be a major challenge. Objectives We developed a custom diffusion-ordered spectroscopy (DOSY) approach for the qualitative analysis of precious Calculus Bovis (CB) and detection of its adulterants. Methods Using Artificial Calculus Bovis as an example, we focused on the effects of NMR spectrometers, solvent viscosity, matrices, matrix concentration, and temperature on separation efficiency of DOSY. The optimal conditions also successfully applied for the identification of Natural Calculus Bovis, Calculus Bovis Sativus, and adulterated samples. The accuracy of DOSY was verified by 13 C NMR. Results Via inspection of NMR spectrometers, solvents, matrices, matrix concentration, and temperature, the optimal conditions for DOSY experiments of CB were found to be using methanol- d 4 as the solvent, adding 4 mg of polyvinyl pyrrolidone (PVP) as the matrix, and a temperature of 298 K. Under these conditions, five types of compounds, cholic acid (CA), deoxycholic acid (DCA), hyodeoxycholic acid (HDCA), taurine-conjugated bile acids (tBAs), and glycine-conjugated bile acids (gBAs), were unequivocally identified in three types of CB. 13 C NMR validated the accuracy of the DOSY results. As for the sugar-adulterated CB, the signals of sugar could be clearly identified on the DOSY spectrum. Conclusions This study verified the feasibility of DOSY for the quality evaluation of CB and provided a reference point for future qualitative and quantitative analysis of other complex traditional Chinese medicines, as well as the characterization of adulterated samples.
Qi Zhao,Christian Marcus Pedersen,Jiamin Wang,Rui Liu,Yuanli Zhang,Xiuyin Yan,Zhenzhou Zhang,Xianglin Hou,Yingxiong Wang
The component analysis and structure characterization of complex mixtures of biomass conversion remain a challenging work. Hence, developing effective and easy to use techniques is necessary. Diffusion-ordered NMR spectroscopy (DOSY) is a non-selective and non-invasive method capable of achieving pseudo-separation and structure assignments of individual compounds from biomass mixtures by providing diffusion coefficients ( D ) of the components. However, the conventional 1 H DOSY NMR is limited by crowded resonances when analyzing complex mixtures containing similar chemical structure resulting in similar coefficient. Herein we describe the application of an advanced diffusion NMR method, Pure Shift Yielded by CHirp Excitation DOSY (PSYCHE-iDOSY), which can record high-resolution signal diffusion spectra efficiently separating compounds in model and genuine mixture samples from cellulose, hemicellulose and lignin. Complicated sets of isomers ( d -glucose/ d -fructose/ d -mannose and 1,2-/1,5-pentadiol), homologous compounds (ethylene glycol and 1,2-propylene glycol), model compounds of lignin, and a genuine reaction system (furfuryl alcohol hydrogenolysis with ring opening) were successfully separated in the diffusion dimension. The results show that the ultrahigh-resolution DOSY technique is capable of detecting and pseudo-separating the mixture components of C 5 /C 6 sugar conversion products and its derivative hydrogenation/hydrogenolysis from lignocellulose biomass.
危险品化学品经营许可证（带存储）