The US National Institute of Standards and Technology has added tens of thousands of new chemicals to its Mass Spectral Library, marking the first update since 2017. Multiple industries use the library’s spectra to identify unknown compounds, and the library is incorporated into the software of many mass spectrometers. The update includes 14,000 human and plant metabolites, along with pesticides, pharmaceuticals, illicit drugs like synthetic opioids, and chemicals such as lubricants and surfactants that are used in manufacturing, NIST says. To make the additions, NIST scientists bought samples of the compounds and analyzed them under various conditions. “We carefully acquire and curate the data so users can have high confidence in their identifications,” NIST computational biologist Sara Yang, who worked on quality control, says in a news release. The update adds nearly 40,000 chemicals to the library’s electrospray ionization component, bringing it to a total of 308,000 compounds. The update also doubles the size of the tandem mass spectrometry portion, bringing it to 31,000 substances.