Determination of an unknown system contaminant using LC/MS/MS

In recent years, liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) has become an increasingly valuable tool for the study of contaminants in the environment. It has the advantage of providing structural information while simultaneously reducing background interference. The objective of the investigation presented here was to identify an unknown system contaminant using highresolution accurate mass measurements and LC/MS/MS. In order to accomplish this, a reverse-geometry, double-focusing mass spectrometer equipped with linked scan capability was used. After an accurate mass measurement was performed, an elemental composition determination was carried out to generate a list of potential compounds. Once the list wasnarrowed down to the most likely molecular formula, linked scan MS/MS was used to provide enough structural information to confirm the chosen formula and identify the most probable constitutional isomer. The unknown contaminant was determined to be N-butylbenzenesulfonamide, a common plasticizer increasingly found in the environment.