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Aquaprobe
®
AP-5000 Instruction Manual
10401-00906 Rev M
15.9. 2000/5000-FSCEIN Fluorescein Electrode
Fluorescein is a fluorescent dye that is commonly used in water flow studies and can be
measured by the AP-5000 using the optional 2000/5000-FSCEIN optical electrode.
15.9.1.
Principle of Operation
The 2000/5000-FSCEIN optical electrode is a submersible, fixed response fluorometer,
which provides excitation at 470nm and detects any resultant fluorescence above 550nm.
The electrode induces the Fluorescein to fluoresce, then measures the longer wavelength
light which is emitted as a result of the fluorescence process.
15.9.2.
Limitations of Use
Measurement of Fluorescein in the field using fluorescence measurement techniques can
be adversely affected by:
•
Interference from microbiological species and compounds, which fluoresce at similar
wavelengths.
•
Differences in the fluorescent response caused by temperature.
•
Differences in the fluorescent response caused by ambient light.
•
Interference caused by turbidity.
The normal affects of temperature on the fluorescent response of Fluorescein is
automatically compensated for by the electrode.
15.9.3.
Calibrating the FSCEIN Electrode
The FSCEIN electrode has two calibration points. Careful calibration is essential in order to
ensure consistent and reliable results.
When a FSCEIN electrode is first installed,
it MUST be calibrated at both points
in order
to set the electrode's relative sensitivity and establish its slope.
Subsequently, a single point (Zero) calibration should be carried out daily. Full two-point
calibration should be carried out every few months.
15.9.4.
Calibration Solution Preparation
In order to calibrate the FSCEIN electrode, a 100µg/L calibration solution of Fluorescein
Dye should be used.
The 100µg/L calibration solution should be freshly prepared by serial dilution from 200g/L
standard using deionised water. The following Fluorescein Dye is recommended:
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