Validation of a GC-FID headspace method for quantitative detection of silicone oils (siloxane polymers) within the lyophilisation life cycle

With biological entities increasingly targeting new therapeutic areas, the use of lyophilisation to ensure adequate shelf life during stability and storage remains an important consideration.

An important aspect of the lyophilisation process is the transfer of heat from the stainless-steel shelves to the vial or tray containing the entity. Commonly, silicone oils (siloxane polymers) are used to control this transfer due to their high thermal stability allowing them to function within a wide temperature range.

The potential for siloxane polymers to enter the product chamber may arise through leaks in the system due to general wear and tear associated with years of use, or leaks introduced into the system after improper cleaning and maintenance procedures. A method was developed utilising Gas Chromatography (GC), a Flame Ionisation Detector (FID) and Headspace (HS) sampling technique for determination of eight siloxane polymers. This method can be used as an additional control within equipment cleaning assessment or can be part of additional tests on the lyophilised product.