Stability of metabolites in dried blood spots stored at different temperatures over a 2-year period

Background: Quantitative LC-ESI-MS/MS, developed from newborn screening, is increasingly used for targeted metabolite profiling. Dried blood spots (DBS) provide easily obtainable biological samples but long-term stability data are sparse. DBS were stored at ambient temperature (room temperature [RT]; 21 degrees C), -20 and -80 degrees C. Metabolites were analyzed at 12 time points (0-104 weeks) by LC-ESI-MS/MS, using fully quantitative stable isotope dilution. Results: Principal component analysis showed alterations in metabolite stability at different temperatures, with major changes only at RT. Univariate analysis for individual analytes demonstrated increases or reductions in concentration. Conclusion: Significant changes are observed in certain DBS metabolites at RT, which are attenuated or not present when frozen. These data will help to inform the design, analysis and interpretation of future DBS studies.