Mettler Toledo GA42 Operations Instructions download pdf (Page 27)

METTLER TOLEDO DL36 25

Sample determinations

9.3 Tips for accurate determinations

1. We advise always using the DL36 in the operating mode "Pretitration" (standby titration).

2. Always wait for a stable drift before you inject the sample. This allows determination of an

exact value for the drift change per minute, which is incorporated in the calculation of the

result.

3. Titrate the cell overnight when you determine samples whose absolute moisture content

is less than 50 µg (standby titration).

4. With a low moisture content, rinse the syringe with the sample before you perform the first

titration.

5. Check the DL36 by measurements with a reference substance, e.g. Hydranal

check

solution from Riedel-de Haën.

6. Change the reagents when

• the anolyte solution reaches a volume of 150 mL (second mark on the titration cell),

• the capacity of the catholyte or anolyte is exhausted (see Section 11.6),

• the drift is too high (>10 µg/min).

7. Always titrate a sample series with the same stirring speed.

9.4 Applications

We have developed applications for volumetric and coulometric titrations which can be used

to determine moisture in solvents, petroleum products, plastics, foods and cosmetics. The

applications include

• instructions for sample preparation

• advice for substances which cause side reactions in the titration

• literature references.

They are listed in Section 12.2.

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Mettler Toledo GA42 Operations Instructions Page 27