| Summary: | 碩士 === 中原大學 === 化學研究所 === 100 === The development of poly(alkyl methacrylate-co-divinylbenzene) based monoliths as stationary phases in capillary electrochromatography (CEC) was studied. The poly(SMA-DVB) monolith was used in the CEC method using a step gradient elution for the analysis of eight phthalates. Results indicated that the step gradient elution (optimization of the mobile phase condition for the gradient step and separation step as well as ramp time) effectively reduced the retention behaviors of the highly hydrophobic phthalates. The effect of the polymerization condition (varying ratio of monomers) of the poly(SMA-DVB) monolithic stationary phase on the separation efficiency were examined. The optimized monomer ratio was 1:5 for monomer SMA and crosslinker DVB. The mobile phase condition of the first step was chosen as 60% ACN for 5 min, for the second step was 65% ACN for 2 min (ramp time, 1 min), and the final step was 92.5% ACN for another 13 min (ramp time, 1 min). This study indicated that the eight phthalate esters (PAEs) achieved reproducible baseline separation within 16 min.
The optimized column and mobile phase conditions in normal mode were used in on-line concentration method (step gradient elution). Furthermore, the sample matrix and sample injection time were adjusted to improve sensitivity and resolution. The detection limit was decreased about 30 times with on-line concentration method which was in the range of 0.02-0.63µg/mL. Detection limit was in the range of 0.52-2.81 ngmL -1 by the CEC-MS mode.
Finally, The optimized column used in on-line concentration method (step gradient elution) by the CEC-MS mode. The detection limit was decreased that detection limit was in the range of 0.52-2.81 ngmL -1.
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