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The composition of printing inks varies by the solvent base, be it oil based or water based. Moreover, it varies by drying mechanism and whether the drying is primarily by a chemical or a physical processes. High humidity and high levels of water will emulsify in the ink and will slow ink drying.
The method presented is based on Metrohm’s 851 Titrando coulometer in conjunction with an 874 Oven Sample Processor. The ink (and substrate) is weighed into a vial and the top is sealed (crimped). This sample is then put on the rack of the 874 Oven Sample Processor. The sample is heated up in the oven and the released water titrated in the coulometric cell of the 851 Titrando. The refined methodology of this technique brings decisive advantages:
- Strictly reproducible analysis conditions for all samples, which is shown by the considerably improved precision of the results
- Manual sample preparation is reduced to a minimum, just «weigh, crimp and analyse»
- Considerable savings in time and money, less reagent costs for example, no more acid and solvent extraction
- No contamination of the oven, consequently there is no carryover and memory effects
- Improved water release from the sample as the carrier gas does not just pass over the sample but directly through it
- Fast analysis times; typically 3 minutes, and up to 35 samples at a time!
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