Preparation of thiol- and amine-bifunctionalized hybrid monolithic column via "one-pot" and applications in speciation of inorganic arsenic.

A thiol- and amine-bifunctionalized organic-inorganic hybrid monolithic column was prepared for the first time via one-pot co-condensation of 3-mercaptopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane and tetraethylorthosilicate, and utilized for separation and enrichment of inorganic arsenic species. Various parameters of solid phase microextraction (SPME) operation and analytical performance were also investigated systematically. Under the optimum condition, both As(III) and As(V) can be adsorbed over a wide pH range (3.0-8.0) and eluted in turn, in which 3% HNO3 (v/v) was firstly used to selectively release As(V), and then 3% HNO3 with 0.01 mol L-1 KIO3 or 15% mercaptosuccinic acid (MSA) (m/v) to selectively release As(III). Meanwhile, the elution mechanism of As(III) and As(V) was elucidated comprehensively, and notably, the novel eluent, HNO3 + MSA, was recommended for eluting As(III). Therefore, the thiol- and amine-bifunctionalized organic-inorganic hybrid monolithic column as an ideal SPME matrix for the speciation analysis of arsenic in environmental waters has the merits of facile preparation, low cost, high adsorption capacity and selective desorption. In addition, compared with thiol- and amine-bifunctionalized mesoporous silica, the bifunctional hybrid monolith based SPME protocol with less time and reagent consumption is promising to be applied not only to filed sampling but also to on-line analysis.