Metrohm 851 Titrando Bedienungsanleitung PDF herunterladen (Seite 45)

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4 Coulometric titration

851 Titrando

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Pull the piston of the syringe up to the end and swing the syringe

back and forth somewhat.

The inside of the syringe is being rinsed by water standard and freed

from water contamination.

Dispose of the used water standard in a waste bottle.

Draw the rest of the water standard into the syringe, aspirating as lit-

tle air as possible.

Push out any air bubbles that may be present in the syringe.

Wipe off the needle with a lint-free paper towel and cover it with the

appropriate cap.

Place the syringe on the balance and press [TARA].

As soon as the drift on the 851 Titrando is stable, take the syringe by

hand, press [START] and inject approx. 1 mL of the water standard

through the septum.

There are two possibilities:

￭ Version 1:

Inject the water standard without immersing the needle in the

reagent liquid. If a little drop remains on the end of the needle, it

must be aspirated back before pulling the needle out of the sep-

tum.

The water standard should not be sprayed from the syringe onto

the electrode nor onto the wall of the coulometer cell.

￭ Version 2:

Inject the water standard directly under the surface of the reagent

liquid.

Take care to ensure that you do not aspirate any liquid when you

withdraw the syringe from the reagent liquid.

Close the syringe with the same cap and place it back on the bal-

ance.

Read off the value displayed by the balance and enter it as sample

size on the Touch Control or in the PC software (e.g. tiamo).

If you have connected a balance to the Titrando, you may transmit

the sample size directly from the balance.

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Metrohm 851 Titrando Bedienungsanleitung Seite 45