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Analysis of nanoliter samples of electrolytes using a flow-through microfluorometer
V R Zhelyaskov1, S Liu, M P Broderick
1World Precision Instruments, Inc., Sarasota, FL 34240-9258, USA. valentin@wpiinc.com
Kidney International
|April 12, 2000
Summary
Researchers enhanced the NANOFLO microfluorometer to measure sodium, calcium, and chloride ions in nanoliter samples. This advancement enables precise electrolyte analysis in ultralow volumes for physiological studies.
Area of Science:
- Biomedical Engineering
- Analytical Chemistry
- Physiology
Background:
- Studying transport properties of nanoliter renal tubule samples requires specialized techniques.
- Existing methods like continuous flow colorimetry and fluorometry have limitations for certain analytes.
Purpose of the Study:
- To extend the NANOFLO microfluorometer's capability for analyzing sodium (Na+), calcium (Ca2+), and chloride (Cl-) ions.
- To adapt the NANOFLO for ultralow volume electrolyte measurements in physiological research.
Main Methods:
- Utilized three commercially available fluorescent indicators for intracellular and extracellular ion measurements.
- Selected indicators based on optimal dissociation constants and analyte concentration ranges.
- Employed Fluo-3 dye for Ca2+, sodium green dye for Na+, and lucigenin dye for Cl-.
Main Results:
- Achieved a detection limit of 0.1 pmol for Ca2+ with 7:1 to 10:1 selectivity over Mg2+.
- Achieved a detection limit of 12 pmol for Na+ with 40:1 selectivity over K+.
- Achieved a detection limit of 10 pmol for Cl-.
Conclusions:
- The enhanced NANOFLO system effectively measures ultralow volumes of key electrolytes (Na+, Ca2+, Cl-).
- This technique offers high sensitivity and selectivity for ion analysis in biological samples.
- The method is adaptable for measuring other physiologically important ultralow volume analytes.