Carbon-13 nuclear magnetic resonance analysis of formaldehyde free preservatives

Preservation of biomolecules is pivotal in increasingly important molecular diagnostics. Traditionally, formaldehyde is employed for such biomolecular preservation in spite of its carcinogenicity. Moreover, formaldehyde induced cross-linking during fixation is reported to alter structural and functional properties of the preserved biomolecules. Therefore, formaldehyde-free preservatives are advantageous because they are safer for laboratory personnel and they protect the structural and functional integrity of the biomolecules. Streck Cell Preservative and Cell-Free DNA BCT reagents are used as formaldehyde alternative preservatives. However, no studies have been carried out to evaluate formaldehyde concentrations in these preservatives. In this study, we evaluated the free formaldehyde concentrations of these reagents by carbon-13 (13C) NMR spectroscopic analysis. Chemically non-invasive NMR analysis is more reliable than the traditional derivatization based techniques in formaldehyde detection. 13C NMR technique can be used for quantitative measurement by using 13C NMR-relaxation agents. In this manuscript, we report an optimized NMR analysis method using Gadolinium diethylenetriaminepentaacetate. Additionally the data reported herein provide spectral analyses that indicate Streck Cell Preservative and Cell-Free DNA BCT reagents do not contain detectable free formaldehyde. Therefore, these preservatives are safer alternatives than formaldehyde for laboratory use, which can protect the overall integrity of the biomolecules within preserved samples.