Relequa ERH test negates lengthy investigations
Relequa
Equilibrium relative humidity test
Relequa has revealed that its equilibrium relative humidity (ERH) test can be used to solve process validation sample issues.
An investigation was begun after process validation samples were seen to be giving results that did not make any sense.
Powder-blend samples and tablet samples were all assayed for content at the same time by the same method and on the same equipment.
All the tablets' assay results range from four per cent to eight per cent higher than the powder blends.
Using Relequa, it was found that the tablet samples had high ERH.
The company powered the tablets in a mechanical grinder and saw that this instantly reduced the ERH.
The decreased ERH demonstrates that the tablets had lost moisture.
This was the first instance of tablets showing to have trapped moisture in their matrix.
In a typical HPLC assay the average weight of 20 tablets (Av) is used in the assay calculation: Std x (Av/WS) x (PS/PStd) x 100 per cent.
It is seen from this equation that the weight of the tablets is used on the top line.
The trapped moisture is instantly lost when tablets are powdered and not accounted for in the sample weight (WS).
It was concluded that the increased moisture, demonstrated by the sensitive Relequa ERH test, added to the tablet assay values.
In this case, unfortunately, the process validation results had been generated causing a lengthy investigation and considerable cost that could have been avoided by a using the simple Relequa ERH test.
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