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A dual-wavelength light-emitting diode based detector for flow-injection analysis process analysers
1Centre for Process Analytical Chemistry, Department of Chemistry, Central South University of Technology, Changsha, Hunan 410083, People's Republic of China.
Talanta
|June 1, 1992
Summary
A novel dual-wavelength light-emitting diode (LED) detector for flow injection analysis (FIA) process analyzers was developed. This compact detector offers precise measurements with minimal drift, achieving a 0.24% relative standard deviation for cobalt determination.
Area of Science:
- Analytical Chemistry
- Instrumentation Science
Background:
- Flow injection analysis (FIA) requires sensitive and stable detectors for process monitoring.
- Existing LED-based detectors often have complex optical paths or are limited in wavelength capability.
Purpose of the Study:
- To design and develop a compact, dual-wavelength LED-based detector for FIA process analyzers.
- To achieve high precision and minimize drift in absorbance measurements.
Main Methods:
- A novel optical design using a dual-wavelength LED and photodiode without mirrors or lenses.
- Integration of electronic components including a microcomputer for electronic modulation and simultaneous measurement.
- Utilized D/A converter and multiplexer to equalize light intensities for dual wavelengths.
Main Results:
- Achieved a relative standard deviation (RSD) of 0.24% for repeated measurements of absorbance 0.875.
- Negligible drift due to near-simultaneous measurement of dark current and light intensity.
- Successfully applied the detector for the determination of 10(-6)M cobalt using FIA.
Conclusions:
- The designed dual-wavelength LED detector is a compact and effective tool for FIA process analysis.
- The electronic modulation and simultaneous measurement strategy significantly reduces drift and enhances precision.
- This detector shows promise for sensitive determination of trace analytes like cobalt.
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