Opti-Trace User’s Manual
Page
14
a)
Close the two-way valve flowcell shut-off valve. (The valve is closed when the
handle is horizontal)
b)
Clean the flowcell by injecting a dilute acidic solution, such as 10% Sulfuric
Acid, Hydrochloric Acid, etc, with the accessory syringe into the flowcell. The
syringe screws on to the Luer-Lock fitting on the inlet of the flowcell. After
filling the syringe with 60 mL of dilute acid, screw the syringe on to the fitting,
inject the acid at a slow, steady rate into the flowcell, and allow it to stand for 3
to 5 minutes. Next using a clean 60 mL syringe flush the flowcell thoroughly
with 60 mL of blank solution. Finally, clean the cell with the supplied brush.
c)
The flowcell is now ready to be calibrated.
3. Removing unwanted bubbles in the syringe
Bubbles trapped in the syringe during injection of the blank or calibration standard
are a possible cause of measurement error. To eliminate the bubbles, start with the
syringe in a vertical position, and tap it against a solid object to move the bubbles to
the needle end of the syringe. Then force the bubbles out by pushing a small amount
of solution through the needle end of the syringe.
4. Reducing the effects of temperature changes during calibration
It is important to let readings stabilize before recording them during the calibration
routine. The readings will probably change from when the dye is first injected into
the sample cell as the dye stabilizes to the ambient temperature of the sensor.
Normally, the readings will stabilize within a
minute or so.
5. Linear Range and Quenching
The linear range is the concentration range in
which the Opti-Trace output is directly
proportional to the concentration of the
fluorophore. The linear range begins with the
smallest detectable concentration, and spans
to an upper limit (concentration) that is
dependent upon: the properties of the
fluorescent material; the filters used; and the
path length.
A non-linear relationship is seen at very high
concentrations where the fluorescence signal
does not increase at a constant rate in
comparison to the change in concentration,
see Figure 6 below. At even higher
concentrations, the fluorescence signal will
Figure 5
Opti-Trace fluorometer showing
location of inlet, (bottom) and
cleaning, (top) valves