Influence of carbon deposits and subsequent silylation of silica gel on sorption efficiency of explosive nitramines

A series of carbon/silica (CS) adsorbents was synthesized by carbonization of different amounts of starch bound to silica gel Sipernat 50. To change the adsorption ability of CS in respect to organics with nonpolar fragments, the samples were also silylated by octadecyldimethylchlorosilane. Two sets of CS samples were studied in solid phase extraction (SPE) of three explosive nitramines. The recovery rate of explosives studied in the SPE procedure depends mainly on the amounts of carbon deposits (accessible surface area of carbon phase) in composites. Silylation of the CS samples gives nonlinear changes in the recovery rate which increases for silylated silica gel and CS with small content of carbon deposits and decreases for silylated CS at maximal amounts of carbon deposits.