The School of Pharmacy at the University of Eastern Finland has developed a new method for accurately determining the water content of water-soluble compounds. This is important in areas such as drug dosage. The method makes use of solution-state nuclear magnetic resonance spectroscopy, also known as NMR spectroscopy.
The exact structure and water content of the compound being studied are critical in pharmaceutical research and development because they affect both the physicochemical and pharmaceutical properties of the compound. Furthermore, the water content influences the total molecular weight of the compound, which is required for calculating the correct drug dosage.
The research also revealed that the previously determined water content may change during storage. For example, the commercial sodium salt of citric acid had changed from a form containing 5.5 crystal water molecules to one containing 2 crystal water molecules.
Tuulia Tykkynen
Titration and thermogravimetry (TGA) are the most commonly used methods for determining the water content of chemical compounds. However, most methods necessitate precise weighing, destroy the sample, necessitate specialized knowledge, or are time-consuming.
The study’s NMR method is simple and accurate, and it works very well for determining the water content of water-soluble compounds, as the NMR results were comparable to the water contents determined by TGA and X-ray crystallography.
“The research also revealed that the previously determined water content may change during storage. For example, the commercial sodium salt of citric acid had changed from a form containing 5.5 crystal water molecules to one containing 2 crystal water molecules,” Senior Researcher Tuulia Tykkynen and Senior Researcher Petri Turhanen of the University of Eastern Finland point out.
The NMR method has several advantages, including ease of sample handling (no accurate weighing is required), speed (the measurement of one sample and calculation of the result takes approximately 15-20 minutes), and the ability to recover the investigated compound after the measurement because the method does not destroy the sample. Furthermore, the method is precise and repeatable. An NMR spectrometer is a costly investment, but it can be stated that the equipment is almost always found in laboratories where new compounds and pharmaceuticals are synthesized, as it is an essential tool for structure determinations.
