Synthesis of Silica@Graphene Oxide and Their modification with polystyrene as a Separation Media for Pesticides and Dyes in Liquid Chromatography

초록

A new separation media was synthesized for the separation of pesticides (imidacloprid and carbofuran) and dyes (acid yellow 25 and acid black 210). Graphene oxide and monolithic silica were coupled by a renovated Fischer's esterification protocol and the composite was grounded to small particles. The resultant particles were treated with 3-amino propyltrimethoxy silane and sodium diethyldithiocarbamate in seqeunce. A uniformly distributed thin polystyrene layer was immobolizied on the surface of composite particles via reversible addition fragmentation chain transfer polymerization. The product was characterized by Brunauer Emmett Teller analysis, Xray diffraction, Fourier transform infra-red, and zeta potential and packed in stainless steel columns (1.0 mm I & sdot;D x 300 mm long). Surface area of the polymer attached silica bound graphen oxide is 264.88 m2.g-1 with radius of 26.6 nm. The column resulted in very good chromatographic performacne in terms of computation of values for different chroamatographic parameters such as retention time, number of theortical plates, HETP, capacity factor, separation factor, and resolution for dyes and pesticides. ACN/H2O (60/40 V/V%) with 1 % formic acid at pH 2 was used as the optimum mobile phase with a flow rate 15 mu L/min for the separation of pesticides while ACN/H2O (90/10 V/V%) with 1 % formic acid at pH 2 with a flow rate of 15 mu L/min was used as the optimum elution conditions for the analysis of dyes. The injected volume was used 20 mu L. The number of theoretical plates/column as high as 22,210, 21722, 21961, and 23,145 were obtained for carbofuran, imidacloprid, acid yellow 25, and acid black 210 respectively. The polymer modified composite materials could be a best candidate acting as a solid phase extraction media which could be used in a variety of applications.

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