15
Operation
solution dans le tube d'échantillon sera bouillante ou sur le
point de bouillir.
The tubes are not closed systems and cannot explode. The
pressure inside the tubes is very close to that of the atmosphere at
all times.
Note: Do not refrigerate Micro Dist tubes. This will cause the membrane
ring to shrink and the trapping solution to leak out.
4.2.1 Filling and Assembling the User-Fill Collector Tubes
The User-Fill collector tube option is designed for the user who:
• wishes to fill the collector tube just before use, thus
avoiding any unwanted evaporation after the foil pack is
opened.
• wishes to reduce shipping costs by receiving a dry product.
• wants to design a custom trapping solution.
• wants to keep tubes in stock indefinitely.
Lachat Instruments takes great care in filling the pre-filled collector
tubes accurately and precisely. The tube's performance depends
greatly on adding the correct, precise aliquot of trapping solution.
Trapping solution recipes for each of the Micro Dist™ tubes
available from Lachat Instruments can be found in Table 3 on
page 67.
When measuring the trapping solution aliquot by volume, the
manufacturer recommends that a good quality re-pipettor be used
to dispense the trapping solutions into the collector tubes. A
hand-held automatic pipet can also be used, but this will be less
convenient. Always calibrate any automatic pipet before using it by
dispensing 1.0 mL water onto a top-loading balance. 1.0 mL water
should weigh 1.0 g.
4.2.2 Filling and Assembling the Collector Tube
In the following procedure, D and M refer to the marks on the ends
of the collector tube.
D means 'distillation' or 'discarded' end and M
means 'measuring' end. See on page 17.
1. Place as many collector tubes as will be used in one day in a
rack, with the
D end down and the M end up. For very
low-concentration work, such as ammonia, rinse each tube with
deionized water first.
2. By Volume: With the re-pipettor or automatic pipet, dispense
the volume of trapping solution specified in Table 3 on page 67,
into the M end of the collector tube.
3. By Weight: Place the rack of collector tubes onto a 0.01 g
top-loading balance. Zero or tare the balance. With a
disposable pipet or wash bottle, dispense the weight of trapping
solution specified in Table 3 on page 67, into the
M end of the
collector tube.
4. Repeat step 2 or 3 for each collector tube in the rack.
5. Pick up a filled collector tube and set the
D end down on the
bench.
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