Moisture analysis is a critical parameter during the manufacture of solid pharmaceutical bulk drugs. New equipment from Metrohm promises to make life easier
Fast and accurate determination of the moisture is the order of the day for pharmaceutical manufacturers, since the manufacture of these expensive drugs is often very difficult and can take days to produce.
Many of these pharmaceutical products can contain components which maybe harmful if touched or inhaled. Oven methods, for example, loss on drying and halogen lamp balances, are often slow and inaccurate because these instruments tend to measure all volatiles within the sample and not just water.
Classical Karl Fischer techniques cannot be used when absolute accuracy is required because opening up the KF cell to the atmosphere, when adding the solid to the cell, allows additional moisture into the cell which will in turn be titrated thus giving spurious results.
Many pharmaceutical products are also known to react with KF reagents, thus giving rise to side reactions, which in turn produces unwanted water.
Metrohm has developed the 774 Oven Sample Processor in conjunction with the 756 Coulometer to overcome these type of problems completely plus enabling moisture analysis to be conducted by the pharmaceutical companies 24hrs a day, sevev days a week.
The sample is weighed into a vial (or pre freeze-dried products can be used directly) and placed into an oven.
The sample is heated and the moisture generated is transferred to the coulometer cell via a flow of dry nitrogen.
The resulting water is then titrated using the Karl Fischer technique.
Typical analysis time is three minutes.
The instrument is also capable of measuring bound and unbound moisture of the samples using the temperature ramping function on the processor.
Only water is titrated in the coulometer so there is no possibility of side reactions taking place since all the unwanted components are left safely behind in the vial.
Up to 35 samples can be measured automatically.
