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Author Laugere, F. ♦ Bastemeijer, J. ♦ van der Steen, G. ♦ Vellekoop, M.J. ♦ Sarro, P.M. ♦ Bossche, A.
Sponsorship IEEE Sensor Council
Source IEEE Xplore Digital Library
Content type Text
Publisher Institute of Electrical and Electronics Engineers, Inc. (IEEE)
File Format PDF
Copyright Year ©2002
Language English
Subject Domain (in DDC) Technology ♦ Engineering & allied operations ♦ Applied physics
Subject Keyword Electrokinetics ♦ Detectors ♦ Electrodes ♦ Conductivity measurement ♦ Semiconductor device measurement ♦ Differential amplifiers ♦ Signal generators ♦ Signal detection ♦ Signal to noise ratio ♦ Lithium
Abstract Liquid conductivity detection for application in chip-based capillary electrophoresis (CE) has received attention because the sensor electrodes can be integrated in the chip and there is no loss of sensitivity when downscaling the detector. A well known disadvantage of conductivity detection is the high level of the baseline (due to the conductivity of the carrier electrolyte) that has a high influence on the measured values and deteriorates the detection limit. By using a lockin amplifier, making use of its two differential inputs and of its phase-locked sinewave output, we can generate a signal of controlled amplitude and phase, related to the level and phase of the baseline signal. By subtracting this signal from the AC output signal of the detector the baseline is significantly suppressed. Ideally, only the changes of the background signal are then measured. When applying the baseline-suppression method to real measurements, the level of the background signal was decreased 50 times. The detection limit (which is related to the signal-to-noise ratio) was found to be 10 times lower. Reproducible separations with concentrations from 1 mM down to 10 /spl mu/M of potassium, sodium, and lithium ions were obtained. For our separation and detection system, the concentration of 10 /spl mu/M could not be detected without the baseline-suppression technique described here.
Description Author affiliation: Electron. Instrum. Lab., Delft Univ. of technology, Netherlands (Laugere, F.; Bastemeijer, J.; van der Steen, G.)
ISBN 0780374541
Educational Role Student ♦ Teacher
Age Range above 22 year
Educational Use Research ♦ Reading
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2002-06-12
Publisher Place USA
Rights Holder Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Size (in Bytes) 301.77 kB
Page Count 4
Starting Page 450
Ending Page 453

Source: IEEE Xplore Digital Library