Excipients add flavor, color and other non-API value in pharmaceutical manufacturing

Excipients perform many functions in the pharmaceutical industry such as flavoring, preserving, coloring, filling and lubricating.  While they are not the active pharmaceutical ingredient (API) excipients are nonetheless subject to strict approval processes.  Moisture content of excipients is among the quality control measurements, and a moisture analyzer is a fast, accurate way to confirm excipient moisture content at bulk processors of excipients.

Compact desktop moisture analyzers such as the Kern MLB series can replace large drying ovens to test moisture content of various excipients and their differing moisture content specifications.  These combine a halogen heater mounted on a precision analytical balance and measure moisture content using the thermogravimetric process that yields loss of weight on drying (LOD).

Operating the Moisture Balance

Because certain excipients may be hygroscopic institute a practice of testing immediately after samples come out of the processing stream.  As testing will vary depending on the nature of the excipient the procedure described here is to be used only as an example.

The moisture balance should be located on a firm level surface away from drafts.  Avoid moving the balance because that may necessitate a recalibration exercise. 

• Use the keyboard to program the test parameters for the particular excipient into the unit.
• Place a clean sample plate onto the moisture analyzer sample plate holder and tare the balance.
• Spread a small sample of the excipient evenly on the sample plate taking care to avoid lumps. The weight of the sample will be shown on the LCD.
• Closing the lid on the moisture balance initiates the process.

There are two shut-off criteria:  when the set time has expired or when there is no longer a loss of weight.  The difference between the starting weight and the ending weight discloses the moisture content as measured by loss on drying.  Moisture analysis data are shown on the LCD.  You will support GLP protocol by using an RS232 interface to transfer the data to a standard printer or PC for record keeping.

In summary, a compact moisture analyzer such as the MLB-N available from Tovatech is much easier to use and much faster than microwave-size drying ovens.   But remember that these precision instruments must be used carefully and recalibrated on a regular basis for weighing and temperature accuracy.  All procedures should be included in your organization’s operations manual. 

Rely on the scientists at Tovatech for help in selecting the correct moisture balance based on your requirements, and in establishing proper operating procedures to maintain its accuracy.

How do you measure a product’s moisture content in your processing facility?

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