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Macro 900 Operation Manual
15.4. PT 1556 Chlorophyll Probe
Chlorophyll can be measured by the MAP 2000/2100 using the optional PT 1556
Chlorophyll optical probe.
15.4.1.
Principle of Operation
The PT 1556 Chlorophyll optical probe is a submersible, fixed response
fluorometer, which provides excitation at 470nm and detects any resultant
fluorescence above 630nm.
The probe induces the chlorophyll to fluoresce, then measures the longer
wavelength light which is emitted as a result of the fluorescence process.
15.4.2.
Limitations of Use
Determination of chlorophyll in the field using fluorescence measurement
techniques will never be as accurate as measurements made in a lab using
either cell counting or analysis of molecular chlorophyll after its extraction from
cells.
Factors adversely affecting accuracy include:
Interference from other microbiological species and compounds, which
fluoresce at similar wavelengths.
Differences in the fluorescent response between various species of
phytoplankton.
Differences in the fluorescent response caused by temperature.
Differences in the fluorescent response caused by ambient light.
Interference caused by turbidity.
Fluorescence measurement techniques are ideal for researchers who are
interested in detecting the presence or absence of a specific substance and
measuring relative fluorescence changes that can be used as an indication of
increasing or decreasing concentrations.
Fluorescence
measurement
measurement. In order to obtain more accurate results, data obtained
with the fluorometer in the field should be post-calibrated with data
from standard laboratory analysis of grab samples acquired during the
study.
15.4.3.
Calibrating the CPHYLL Probe
The CPHYLL probe has two calibration points. Careful calibration is essential in
order to ensure consistent and reliable results.
When a CPHYLL probe is first installed, it MUST be calibrated at both points
in order to set the probe's relative sensitivity and establish its slope.
Subsequently, a single point (Zero) calibration should be carried out daily.
Calibration of the CPHYLL probe Zero point is normally carried out during
MacroCal (see
MacroCal Calibration
© 2013 Palintest Ltd.
techniques
are
Method).
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not
ideal
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