6
SYSTEM OPERATION
1.
Use a liquid sample of at least 1.5 ml and place
it in a standard 1 x 1-cm square cuvette. Place
the cuvette in the cuvette holder in the center
of the
qpod 2e
. Standard microcuvettes may
also be used for smaller volumes. The
qpod 2e
is designed to hold microcuvettes in which the
“z” dimension (distance between the bottom
of the cuvette and the optical center line) is 8.5
mm.
Note:
The
qpod 2e
is intended to hold a cuvette
with a standard wall thickness of 1.25 mm and total
width of 12.5 mm. Cuvettes with unusually thick
walls will not properly fit and may damage the
holder.
2.
Place the magnetic stir bar in the cuvette.
Stirring speed will be set by the program Q-
Blue.
3.
If you wish to monitor the temperature inside
the cuvette, plug a standard Series 400 or
Series 500 thermistor probe into the ¼ - inch
phone jack located on the corner of the qpod
2e to the left of the front panel. Thread the
probe through the split rubber plug in the qpod
2e cap and place it in the cuvette out of the
way of the light.
4.
Provide a source of light and a detector.
5.
Use the 5/64-inch hex driver from the
accessory kit to maximize the signal by
adjustments of the three fiber steering screws
(
Figure 3
). This adjustment will make small
movements of the position of the fiber end
relative to the lens. Also, loosen the set screw
to insert the silver sleeve deeper into the lens
assembly. Inserting the silver sleeve further
into lens assembly moves the end of the fiber
closer to the lens, altering the focus of the
light. This adjustment is most important at UV
wavelengths. (Measurements can be made
without these alignments. However, in the
unaligned system the reference spectrum may
change with temperature and must be re-
measured each time the set temperature is
changed. Careful alignment will minimize such
artifacts.)
6.
Use the optical slits or blanks (provided in the
qpod 2e
accessory kit) around the cuvette in a
manner that correctly limits the excitation and
emission light.
7.
Put the cover and cap on the
qpod 2e
.
8.
Turn on the submersible pump by plugging it
in. Cooling water flows through a heat
exchanger and removes heat from the
thermoelectric device when the temperature
of the holder is being lowered. Insufficient
flow will allow the heat exchanger temperature
to rise. If the temperature of the heat
exchanger exceeds a certain cutoff value,
temperature control will be automatically shut
down to protect the holder.
Cooler circulating water can result in improved
performance of the cuvette holder at low
temperatures, whereas warmer water can
improve performance at very high
temperatures.
Do not use warm or room
temperature water when setting
temperatures near room temperature, as
temperature instabilities are likely to arise.
Cool the circulating water by the addition of ice
to the bucket.
A refrigerated circulating bath may be used to
provide circulating fluid to the
qpod 2e
. Using
such a bath, temperatures well below the
specified -30 °C lowest temperature may be
readily achieved. Contact us for suggestions on
how to achieve very low temperatures.
9.
Plug power from the AC adapter into the qpod
2e front panel.
10.
Connect the qpod 2e to your computer using
the USB cable.
