Research highlights: challenges in the characterization, storage, and isolation of natural organic matter.

Dissolved organic matter (DOM) is a critical component of natural waters, providing an important nutrient source for the microbial community, binding and interacting with metals and pollutants, and serving as a major reservoir of carbon in the global carbon cycle. Differences in organic material origin as well as biotic and abiotic transformation processes produce DOM of varying composition. These highly complex mixtures are difficult to characterize due to the diversity of compounds found in DOM. This Highlight examines three recent publications that study the methods used to characterize DOM and how storage and handling of DOM samples may affect its composition. Collectively, these publications underscore the challenges that researchers face when working with natural organic matter and offer important considerations for natural organic matter handling and analysis.