Particle Size Discrepancy Between Bulk Silica Gel Products

When you work in a purification process development laboratory, you undoubtedly want to screen several silica gel products from various manufacturers in order to determine which silica product has the best selectivity and overall yield for your given API. To design a robust screening study, the process development scientist knows to compare “apples to apples.” 

It might not be well-known, but there can be a difference in the particle size values published on Certificates of Analysis (so-called “nominal” size) versus actual particle size with some silica gel suppliers. Naturally, different particle size measurement methods will yield different results, and to be fair these measurements are quite challenging to begin with given the small micron size of the bits we are measuring in addition to the statistical spread of individual particles being measured.

That said, the column back pressure should be a sensitive way of estimating the size of particles packed. Columns of the same dimensions packed with different media but operated under the same eluent, flow rate, and temperature conditions but giving different backpressures is one clue.

Rest assured that the stated particle size for DAISOGEL products (D50*) matches the actual particle size based on measurement, although we always encourage our customers to verify for themselves if they so desire. For other silica gel products, if visual or measurement check are not available to you simply use this rough conversion table that we have prepared between the suppliers’ CoA stated nominal particle size values and actual values by our measurement.