Water Activity Determination with NIRS

Water activity (aw) is a critical parameter affecting product stability, making accurate measurement essential. Traditionally, Headspace Analysis (HSA) has been the standard for non-invasive water activity determination. However, according to USP<922> water activity can also be determined by another non-invasive technology namely Near Infrared Spectroscopy (NIRS).

Both methods provide highly correlated results, but NIRS offers additional advantages by enabling simultaneous analysis of moisture content and material composition. This allows for real-time process monitoring without sample destruction. 

This makes it a versatile solution for complex formulations and freeze-dried products, where precise moisture control is critical. Furthermore, its ability to perform continuous, in-line monitoring enhances process efficiency by reducing the need for destructive testing methods.

At WILCO we performed an extensive research comparing both HSA and NIRS technologies for the determination of water activity for a wide range of pharmaceutical products such as powders, tablets, and lyophilizates. These studies have demonstrated strong correlation between the two technologies allowing customers to choose the most suitable method for their specific applications. With decades of expertise in HSA and NIRS, WILCO helps you select the best method tailored to your individual application needs.