Mechanical Strength Differences Between Grades of DAISOGEL

The mechanical strength of a chromatographic silica gel product is basically determined by its manufacturing process. The SOL-GEL method we use is a sure ticket for the best quality products. That said, there are differences in mechanical strength of the products in our portfolio.

In the wide DAISOGEL lineup we offer the Wide Pore and Super Wide Pore varieties. As you might imagine, the wider the pore diameter of silica gel, the gentler care the product needs. In that sense, wider pore silica must be packed at lower packing pressure to avoid damage to the particles.

A similar concept holds true for particle size; just like any object made of glass, the larger the particle, the less compressive load it can bear due to the larger surface area exposed to the compressive force. For silica gel, this equates to lowering the packing pressure to prevent mechanical damage when packing larger particles. Our 40 μm and especially 50 μm particles must therefore be packed at lowered piston pressures. However, for DAISOGEL products with particle sizes up to 20 μm particle size, “no holding back” is the policy; customers may use the DAC columns at their maximum packing pressure.

Mechanical strength is not an issue under normal circumstances. But there are instances of silica gel handling in our industry which can create risk of damaging the particles. For example, there is always a small level of damage done to a few silica particles during packing. Therefore, repeated packing, unpacking and repacking can ultimately cause significant damage to any silica. The pack-unpack-repack scenario is not uncommon, either; it can occur when production of the API is performed on a campaign basis, or if the silica is used in multi-purpose manufacturing facility such as at a CDMO.

Additionally, there can be chemical damage to silica gel. NaOH-based CIP can weaken silica particles. The worst-case scenario occurs when repeated NaOH based CIP is combined with unpacking and re-packing of the column. Insulin and insulin analog API manufacturing processes are infamous for this. In case you need to perform both caustic CIP and re-packing, the best solution is to use our strongest silica product, the PK Series.

Available in ODS, C8, and C4 bonded phases, DAISOGEL products in the PK Series are specially manufactured to offer superb mechanical strength. An extra hardening step of “calcination” or heat treatment of the silica has been introduced into the PK Series manufacturing process to serve this purpose.