• The first generationof HPLC silicawas typeA
made from inorganic sols. The second generation
includes base deactivated silica preparedby
various chemical treatments of typeA silica to
remove surfacemetals.Metal impurities in silica
are commonlyknown tohave a detrimental effect
onpeak shape of basic analytes. It has been
theorized that at least some of the improvement in
base deactivationobtained following chemical
removal ofmetalsmay be due to the resulting
physical changes of the silica (i.e. pore shaping).
