Preparation Of A Polymer Monolith And Its Application In Solid Phase Microextraction Of Brominated Flame Retardants

Because of its simple preparation, abundant surface chemical properties and good biocompatibility, polymer monolith has been applied in the areas of high performance liquid chromatography, capillary electrochromatography and solid phase microextraction. In recent years, the development of mixed-mode monolithic material has become a hot spot. The mixed modes of the monolithic materials which offer different retention and separation ability to different analytes include hydrophilic interaction, hydrophobic interaction, ion exchange and ion exclusion, etc. In this work, poly(trimethyl-2-methacroyloxyethylammonium chloride-co-ethylene glycol dimethacrylate)(poly(MATE-co-EGDMA)) monolith has been prepared and characterized by a variety of means, then it was applied in solid phase micro-extraction of brominated flame retardants.1. Preparation and characterization of poly(trimethyl-2-methacroyloxy-ethylammonium chloride-co-ethylene glycol dimethacrylate) monolithTo prepare the monolithic material with mixed-mode, we used ethylene glycol dimethacrylate (EGDMA) and trimethyl-2-methacroyloxyethylammonium chloride (MATE) as the crosslinker and the monomer, respectively, and the resulting monolith has a mixed-mode of hydrophobility and strong anion exchange ability. By changing the amount of each component in the pre-polymerized solution, we optimized the permeability and porosity of the monothic material, this optimized monolith has both good mechanical strength and chemical stability. The frontal analysis proved the big loading capacity of the monolith and swelling test proved little swelling or shrinkage of the monolith. We also selected two kinds of model compounds alkylbenzenes and weak acids to characterize the chromatographic performance of the poly(MATE-co-EGDMA) monolith. The results make it clear that the interaction which dominates the retention of alkylbenzenes on the monolithic stationary phase is hydrophobic interaction. On the other hand, pH value of the mobile phase has a great effect on the retention of weak acids on the poly(MATE-co-EGDMA) monolithic stationary phase, and it can be deduced that anion exchange interaction plays an important role in the retention of weak acids.2. Application of poly(trimethyl-2-methacroyloxyethylammonium chloride-co-ethylene glycol dimethacrylate) monolith in solid phase microextraction of brominated flame retardantsWe used the poly(MATE-co-EGDMA) monolith as the extraction column in the in-tube solid phase microextraction of brominated flame retardants (BFRs) in environmental waters. By coupling the in-tube solid phase extraction to HPLC, we realized the detection of trace BFRs in water samples. By changing the sample pH and ionic strength, and methanol content and sampling volume of the sample solution we obtained the optimized condition of the in-tube solid phase microextraction. The regression equations under this optimized condition for three BFRs,2,4,6-tribromophenol (TBP), tetrabromobisphenol A (TBBPA) and4,4’-dibrominated diphenyl ether (DBDPE) showed good linearity from their limit of quantification to5000ng/mL. The limits of detection were0.2,0.15and0.10ng/mL for TBP, TBBPA and DBDPE, respectively. The recovery of the proposed method was78.7%-106.1%with intra-day relative standard deviation of1.3%-4.4%.