Refer to page #40 -

In many cases of use of commonly-available ODS silica gel fillers, there occur problems of tailing and broadening of basic compounds. Although these problems have been considered to be caused by improper end capping rate, they have not been solved only by improvement of the rate. Therefore, efforts have been made to examine the methods of further octadecyl silylation and secondary silylation and increase the coverage. However, also the metallic content in silica gel is relevant to these problems, and the causes are being identified experimentally. Although direct and indirect influences of residual silanols(neutral, acidic and free silanols) and metal on samples have not been clarified, the low-metallic content fillers, Wakosil®-II Series, show the following results.


Column Size :4.6 mm×150 mm
Eluent :
CH3OH/CH3CN/5 mM
Citric buffer(pH 4)
=10/20/70(v/v)
Flow Rate :1.0 mL/min. at 40℃
Detection :UV 230 nm
Sample :1)Benzoic acid
      2)Sorbic acid
      3)Dehydroacetic acid Na salt

Column Size :4.6 mm×150 mm
Eluent :CH3OH/20 mM
      KH2PO4-K2HPO4(pH 7.6)
     =70/30(v/v)
Flow Rate :1.0 mL/min. at 30℃
Detection :UV 254 nm
Sample :1)8-Quinolinol




Column Size :4.6 mm×150 mm
Eluent :CH3CN/H2O=60/40(v/v)
     +0.05% EDTA・2Na
Flow Rate :1.0 mL/min. at R.T.
Detection :UV 254 nm
Sample :1)Hinokitiol





Examples of application of compounds to be analyzed and fillers
Examples of structures
which are affected
by metal in silica gel
Examples of structures
which are affected
by residual silanol groups
Substance to be analyzed Coordinate bonding capability
High Low
Basicity High Navi Series, Wakosil®-II C18 series Navi Series, Wakosil®-II C18 Series, Wakosil® C18 Series
Low Navi Series, Wakosil®-II C18 Series Navi Series, Wakosil®-II C18 Series, Wakosil® C18 Series,
Wakosil® C18T, N Series


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