Improvement of drug identification in urine by LC-QqTOF using a probability-based library search algorithm.

A common method for identifying an unknown compound involves acquiring its mass spectrum and then comparing that spectrum against a spectral database, or library. Accurate comparison and identification is dependent on the quality of both the library and the test spectrum, but also the search algorithm used. Here, we describe a redesigned probability-based library search algorithm (ProLS) and compare its performance against two predicate algorithms, AMDIS from NIST (NIST) and LibraryView/MasterView (LV/MV), on human urine samples containing drugs of interest that were analyzed by quadrupole-time of flight (QqTOF) mass spectrometry.