Used as a stable isotope-labeled tracer in metabolic studies to track the incorporation of one-carbon units in biochemical pathways. Commonly applied in nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) for precise detection due to its ¹³C label. Enables accurate quantification of formaldehyde-derived metabolites in environmental, biological, and pharmaceutical research. Also utilized in labeling studies of DNA and protein modifications where formaldehyde plays a role as an intermediate.