The inverted library-search algorithm (ILSA) is a method for screening mixtures using in-source collision induced dissociation (is-CID) mass spectra. Broadly speaking, the algorithm searches a set of mixture is-CID mass spectra for partial patterns that are similar to pure compound is-CID mass spectra. In doing so, the ILSA can identify multiple partial patterns in the same mixture spectrum-the logical equivalent to identifying compounds in a mixture. We recently demonstrated that the ILSA could accurately identify components of eleven simple laboratory mixtures containing between two and four drugs using is-CID mass spectra collected with Direct Analysis in Real Time Mass Spectrometry (DART-MS) and the National Institute of Standards and Technology (NIST) DART-MS Forensics Database .