DETERMINATION OF VOLATILE ORGANIC COMPOUNDS IN AIR SAMPLES BY METAL ORGANIC FRAMEWORKS
Project no. 21637 · Status: Kapanmış · 2020
Summary
<p>Solid phase microextraction technique (SPME) is one of the widely used methods in the analysis of volatile organic compounds (VOC). For this purpose, SPME fibers prepared with adsorbents of different polarities are currently used. More sensitive analyzes can be performed by changing the adsorbent materials in the fibers used in the SPME technique according to the target compounds. The development of new fibers is a very important issue due to the disadvantages such as the limited lifetime and selectivity of commercial fibers, as well as their high cost.</p><p>Literature studies show that the VOCs in the indoor environment are very high compared to the external atmosphere. For this reason, it is very important to monitor harmful VOCs in ambient air in a simple, fast and effective way. Among these compounds, benzene, toluene, ethylbenzene, o-xylene, p-xylene and m-xylene compounds known by the abbreviation BTEX are the most frequently encountered compounds in indoor air and recommended to be monitored effectively. Different SPME fibers have already been used for this purpose. In this thesis, it is aimed to develop SPME fibers prepared with metal organic frameworks and to determine BTEX in indoor air with this fiber.</p><p>MOF-801 material was synthesized and coated on stainless steel wire with a thermally resistant epoxy glue. Physical and chemical characterization of MOF-801 adsorbent before coating and SPME fiber prepared with MOF-801 were carried out using techniques such as FTIR (Fourier Transform Infrared Spectroscopy), TGA (Thermogravimetric Analysis), XRD (X-Ray Diffraction Method) and BET (Brunauer-Emmett-Teller Method). Gas chromatography mass spectroscopy analysis parameters such as desorption temperature and time required for BTEX determination with the prepared SPME fiber and sampling parameters such as adsorption time, adsorption temperature, sample volume were optimized. Optimum desorption temperature and optimum desorption time from device analysis parameters were determined as 250oC and 3 min, respectively. It was found that the SPME fiber should be conditioned for 15 minutes at 250oC before the sampling step. For the analysis of BTEX in air samples with SPME fiber, the optimum adsorption time and optimum sample volume were determined as 10 min and 1 L, respectively. It has been shown that BTEX analysis can be performed in ambient air in conditions where the ambient temperature is between 15oC and 35oC. Calibration plots were created for each analyte under optimum conditions and validation parameters such as limit of dedection (LOD), linear range, repeatability, fiber-to-fiber reproducibility were defined. For target analytes, LOD values 12.4 μg/m3 to 48.3 μg/m3, linear range 41.3-17660 μg/m3, intraday repeatability 2.66-4.05% inter-day repeatability 3.77-6.34% and fiber-to-fiber reproducibility were found to vary between 7.51-11.17%. The analysis of BTEX in indoor air was successfully carried out with the developed method by obtaining high recovery values.</p>