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0901814c - Hyperion Fluorometer
3.2. Linear Observation Range
The linear range is the concentration range for which the fluorometer signal is directly proportional to
the concentration of the fluorophore. The linear range starts at the minimum detection limit (MDL)
and extends to the upper limit of the instrument (dependent on fluorophore properties, optical filters,
LED power, sample volume and optical path length).
Hyperion Fluorometers have a calibrated linear response for 2 gain settings (e.g. the ranges 0-40 µg/l
(G5) and 0-800 µg/l (G1) for chlorophyll a). At higher concentrations, unlike analogue devices which
generally flat-line at full-scale deflection (e.g. FSD 5V) the Hyperion will continue to output a signal
which increases with concentration (i.e. meaningful data), though which is no longer guaranteed to
be linear.
At very high fluorophore concentrations, signal quenching can occur, whereby the instrument output
does not increase linearly with fluorophore concentration (roll-off) and may decrease at even higher
levels.
To perform a quick linearity check, dilute the sample 1:1 with RO water. If the reading decreases by
50%, the sample is in the linear range. If the reading decreases by less than 50% or even increases,
the sample is above the linear range.
© 2018 Valeport Ltd
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