Modification of sol-gel hybrid monolith and its application in determination of polycyclic aromatic hydrocarbons

Abstract

A C6-silica hybrid monolithic column was prepared by click reaction with capillary silica monolith. Firstly, an azide-functionalized silica monolithic column was synthesized via sol-gel reaction with tetramethoxysilane (TMOS) and 3-azidopropyltrimethoxysilane (N3PTMS). Then 1-hexyne was covalently immobilized on the capillary monolith by the "azide-alkyne" click reaction to form C6-silica hybrid monolithic column. As an extraction media of polycyclic aromatic hydrocarbons (PAHs), the conditions for the preparation and modification of the monolith were carefully investigated according to the extraction efficiency. The enrichment factors for typical PAHs: naphthalene, phenanthrene, pyrene and benzo a pyrene finally reached 95.9, 14.2, 103.2 and 57.8, respectively. The relative standard deviations (RSDs) for the extraction were lower than 5.5% (intra-day, t = 8) and 7.3% (inter-day, n = 10). Based on the in-tube solid phase microextraction (in-tube SPME), a new determination method for 16 PAHs was developed with high performance liquid chromatography (HPLC). The limits of detection (LODs, SN = 3) were 0.08-3.72 µg/L and the limits of quantification (LOQs, S/N = 10) were 0.26-12.40 µg/L for the PAHs. The spiked recoveries for the PAHs in soil samples were between 82.4% and 110.6% with the RSDs (n = 3) of 2.6%-7.9%. Comparison with the method of United States Environmental Protection Agency (U. S. EPA) for the PAIs determination in soil samples, the results showed good accuracy and high consistency. And the high extraction efficiency with high sensitivity and convenience was also demonstrated in the applications of the new approach.