The apparent diffusion coefficient (ADC) of water is an important property in materials that can be measured using NMR and MRI techniques. Aqueous solutions of polyvinylpyrrolidone (PVP) with well-defined ADC values are used in MRI calibration objects (phantoms) to ensure the accuracy of data across various imaging systems. Thus, the careful preparation of PVP solutions and measurement of their diffusivities is important. In this work, a well-established diffusion protocol on an NMR system at 128 MHz (3 T) is used to measure the ADC of prepared PVP solutions as a baseline. These traceable measurements are compared to two systems that have clinical and industrial advantages: a 128 MHz (3 T) MRI and a 2.4 MHz (56 mT) unilateral NMR. Diffusion measurements are compared across these three MR systems by investigating the uncertainty, bias, and sensitivity of ADC as a function of temperature on each system. Because ADC is a field independent parameter, data from the 128 MHz systems were used to develop a diffusion measurement protocol on the low field unilateral NMR system. While this system has a higher uncertainty, its portability offers promising applications for in situ measurements and quality control in the field and industry.
NMR is a powerful technique for the vaccine industry and a valuable tool for quality control. To illustrate this, we present a comparison between the ELISA immunoassay and a 31P qNMR method developed for the quantitation of a bacterial polysaccharide at the end of the fermentation process. The methods are compared in terms of quality management, safety concerns, cost, and technical characteristics to demonstrate that NMR can be included in the QC release profiles not only as a structural method but also as a quantitative one as described in pharmacopoeia (USP and Ph.Eur.).
This work was funded by Sanofi. All authors are Sanofi employees and may hold shares and/or stock options in the company.