The capabilities of a trace contamination analyzer are discussed and demonstrated. This analytical tool utilizes an electrospray, time‐of‐flight mass spectrometer (ES‐TOF‐MS) for fully automated on‐line monitoring of wafer cleaning solutions. The analyzer provides rich information on metallic, anionic, cationic, elemental, and organic species through its ability to provide harsh (elemental) and soft (molecular) ionization under both positive and negative modes. It is designed to meet semiconductor process control and yield management needs for the ever increasing complex new chemistries present in wafer fabrication. © 2003 American Institute of Physics