Appendix 3: Evaporation Loss; Appendix 4: Vwr Protocol Builder Software - VWR International VWR 10 Instruction Manual

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PPENDIX 3 - EVAPORATION LOSS
Procedure for the determination of evaporation loss
Use the same distilled water, weighing vessel and balance as you will be using for the gravimetric
check.
1. Half fill the weighing vessel with distilled water.
2. Cover the weighing vessel with its lid and place it on the balance using a pair of tweezers.
3. Aspirate a sample.
4. Tare the balance and take the weighing vessel out of the balance.
5. Take off the lid with tweezers.
6. Dispense the sample into a dummy vessel.
7. Replace the lid on the weighing vessel and, using tweezers, replace the vessel on the balance.
8. Read the negative result e
9. Repeat steps 3 to 8, three times to obtain e
10. Calculate the evaporation loss e using the formula:
In normal conditions, this value is usually between 0.01 mg and 0.03 mg.
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PPENDIX 4 – VWR PROTOCOL BUILDER SOFTWARE
Using the Custom Mode
(record the absolute value).
1
, e
2 3
, and e .
4
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