Authors: J A PérezSerradilla M D Luque de Castro
Publish Date: 2007/09/11
Volume: 389, Issue: 5, Pages: 1541-1547
Abstract
Sorbent material packed in a PTFE laboratorymade flow cell located in the specimen holder of an energydispersive Xray fluorescence EDXRF detector has been used for in situ solidphase extraction SPE preconcentration–detection of metals The flow cell was connected to a singlechannel flowinjection FI manifold for full automation of the steps and proper development of the method by two PTFE tubes of 05mm inner diameter introduced into the spectrometer specimen holder by a small orifice without distortion or modification of the instrument The optical window open in the PTFE flow cell was adjusted to the Xray irradiation zone of the spectrometer and fixed to it The approach was tested by using both Pb and Cd aqueous solutions and a Dowex 50 cationexchange resin as a sorbent and flushing the sample through the flow cell for EDXRF measurements after removal of the sample matrix The limits of detection and the limits of quantification LOQs thus obtained were 015 and 05 μg for Pb and 03 and 08 μg for Cd respectively values that allow the approach to be used for the analysis of drinking water by injecting a 100mL sample into the FI manifold taking into account the EC drinking water directives The linear dynamic ranges are between the LOQ and 600 μg for both analytes The method was validated by the standard addition method using tapwater samples In addition the integrated SPE–EDXRF approach enables the study of the variables influencing the sorption step–namely the effects of the volume of sample flushed through the column concentrations of the analytes in the sample breakthrough volume of the resin elution profiles sample pH and retention and elution flow rates–in an automatic cheap fast and precise way
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