Preparation Of Hybrid Monoliths And Their Application In Analysis Of Organic Pollutants

With the rapid development of analytical technique, the sample analysis process is becoming simpler, faster and more automatic. However, higher requirements have been proposed to analyze complex sample. In sample analysis, not only advanced analytical instruments, but also high efficient methods for sample pretreatment are needed. So, it is very important to develop high efficient and environmental friendly pretreatment technique with excellent selectivity and high level of automation. According to separation method of sample preparation, this paper reviewed phase distribution, phase adsorption, field-assisted and membrane separation methods. What’s more, a novel sample separating medium-monolith had been detailed while polymer monolithic column, silica monolithic column and their applications in the analysis of sample were briefly described in this paper.Herein we prepared a divinylbenzene (DVB) monolithic column doped with FesO4and a carbonyl-ion powder (CIP) embedded silica monolith (CIP/SiCh/PDMS). The monolithic materials were characterized by scanning electron microscope, transmission electron microscope and FT-IR spectrum. Both of the columns have large surface areas, good penetrability and uniform internal distribution. They have good sorption capacity for methylmercury (MeHg) and benzene series (BTEX), respectively. When MeHg or BTEX sample solution passes through the monolithic column, the target analytes will be enriched on the column which can separate them from the matrix effectively. This method is simple, convenient, and easy to achieve automation and has good enrichment factor for MeHg and BTEX. It can be applied to the pretreatment of BTEX or MeHg samples. From the thermo gravimetric analysis of the materials, we found that both of these two columns had good thermal stability, thus they could thermally desorb the organics that enriched on them directly.Electromagnetic induction heating (EMIH) technology has overcome some defaults of traditional heating mode. It is characteristic of higher thermal efficiency, good temperature controllability due to free of heat conduction and thermal convection of air. Thus by combining monolithic column with EMIH technology in our work, MeHg and BTEX enriched on the column had been desorbed quickly and equably on line before analyzed in detection system. The level of automation had been further improved.Herein we combined DVB/Fe3O4hybrid monolithic column with atomic fluorescence spectrometry (AFS) to establish a new online method to determine MeHg in water and fish samples. The method contains two parts, one is absorption of MeHg and its desorption by EMIH, the other is blow of MeHg to atomize it in pyrolysis column and detection of the resulted Hg0by AFS. This method has high sensitivity with the detection limit being0.09ng/L. Standard reference material was analyzed for validation of the methodology. The recovery experiments showed good accuracy and precision of the method. So, it has high application value in analysis of MeHg in water and fish samples.We combined home-made CIP/SiO2/PDMS hybrid silica monolith column with gas chromatography (GC) to set up a new method to determine BTEX in water samples. BTEX were carried to sample injector of GC after desorbed by EMIH on line, then they were separated by chromatographic column, finally these analytes were detected in FID. We optimized preconcentration and desorption conditions of BTEX and gas chromatographic analysis condition. This method is very sensitive to BTEX under optimum conditions. The detection limits is ng/L level and the accuracy of this method meets the requirement of common analysis experiment.