We have reported novel column-switching method for the determination of trace amounts of chemical substances in surface water using mass-spectrometry (MS) along with electrochemical detection.Bisphenol A (BPA), which is commonly used for synthesis of polymer resins and has been suspected as an endocrine disruptor was determined at ng/L levels with this method[1, 2].Here we have introduced multi-valve column switching HPLC system with a specially designed pretreatment column.This column-switching system solved a recurrent issue of column clogging and the pretreatment column provided remarkable performance for removal of humic compounds from environmental water samples.Use of this combination controlled ion suppression and increased peak response while using MS as a detection system.