Authors: Jessica L Ammerman Joseph H Aldstadt
Publish Date: 2008/05/17
Volume: 164, Issue: 1-2, Pages: 185-
Abstract
We describe the development and optimization of a sensitive and selective screening method for the measurement of trace levels of microcystins in surface waters Several sample preparation techniques were compared including solidphase microextraction SPME particlebased solidphase extraction SPE and monolithbased SPE A flowinjection FI based approach employing a reversedphase monolithic SPE column was found to be optimal Quantification was performed by directly interfacing the FIbased SPE system to an electrospray ionizationmass spectrometer ESIMS To more safely simulate peptidyl toxins such as the microcystins a model peptide ie angiotensin II was used for method optimization Sample loading flow rate and volume eluent composition and elution flow rate were optimized Sample throughput was six samples per hour a detection limit of 131 ng angiotensin II was demonstrated for a linear dynamic range from 1–1000 ng and 34 relative standard deviation n = 4 100 ng sample Sample volumes up to 1000 ml of surface water could be loaded onto the monolithic SPE disk without exceeding the sorbent’s capacity Unlike conventional particlebased SPE methods the monolithic SPE disk does not need to be replaced between samples and could be used indefinitely The FIbased SPEESIMS method was successfully applied to the determination of microcystinLR the most common of the microcystins in environmental samples and was demonstrated for the direct monitoring of chlorinated drinking water with trends tracked over a period of eight monthsWe thank Professor Colleen McDermott University of Wisconsin–Oshkosh for generously providing the samples of cyanobacteria This work was supported by the UWM Center for Water Security Presented in part at the 57th Pittsburgh Conference on Analytical Chemistry Applied Spectroscopy Orlando FL March 2004
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