Razvoj metode za določanje BTEX v tleh

Račić, Jasmin (avtor), Prosen, Helena (mentor)

Benzen, toluen, etilbenzen in ksileni (BTEX) so okoljska onesnaževala, ki jih uvrščamo v skupino hlapnih organskih spojin (HOS). Nahajajo se v nafti in se uporabljajo v industriji kot topila in prekurzorji za sintezo različnih organskih spojin in materialov. BTEX spojine so za ljudi strupene, pri čemer je benzen tudi kancerogen in teratogen. Ker se najmanjši delež BTEX spojin v okolju nahaja v vodi in adsorbiran na zemlji, je pred analizo potrebna predkoncentracija, pri čemer uporabljamo ekstrakcije, kot je mikroekstrakcija na trdno fazo (SPME). V okviru diplomskega dela sem razvil metodo za določanje BTEX spojin v tleh, pri čemer sem kot ekstrakcijsko metodo za predkoncentracijo analitov uporabil SPME, potem pa sem jih analiziral s plinskim kromatografom sklopljenim z masnim spektrometrom. V splošnem delu so opisane ekstrakcijske in kromatografske metode, s poudarkom na plinski kromatografiji in SPME. V nadaljevanju so podani rezultati optimizacije metode. Opisani so tudi optimalni pogoji za separacijo BTEX spojin s plinsko kromatografijo ter optimalni pogoji za SPME. Poleg opisanega dela so tudi grafično predstavljene umeritvene krivulje za vsako od BTEX spojin, ter vplivi na SPME (tip vlakna, temperatura, pri kateri je izvedena ekstrakcija, čas mešanja vzorca, čas ekstrakcije). Razvita metoda je linearna v koncentracijskem območju od 0,5 μg/g do 5,0 μg/g. Meja zaznave, ki sem jo eksperimentalno določil, je znašala za BTEX spojine med 12,5 ng/g in 50,0 ng/g. Pri SPME se je kot najbolj primerno vlakno za ekstrakcijo BTEX spojin izkazalo CAR/PDMS 75 μm vlakno. Razvita metoda se je izkazala za primerno metodo za določanje BTEX spojin v tleh in je bila tudi preizkušena na realnih vzorcih tal, ki so bila onesnažena z dizelskim gorivom. Razen toluena, ki je bil prisoten v enem od vzorcev v koncentraciji 0,043 μg/g, je bila koncentracija ostalih analitov pod mejo zaznave.

• Jezik: Slovenski jezik
• Ključne besede: GC-MS, SPME, BTEX, HOS, okolje, tla
• Vrsta gradiva: Diplomsko delo/naloga
• Tipologija: 2.11 - Diplomsko delo
• Organizacija: FKKT - Fakulteta za kemijo in kemijsko tehnologijo
• Leto izida: 2020
• PID: 20.500.12556/RUL-117172
• COBISS.SI-ID: 21060099
• Datum objave v RUL: 29.06.2020

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Development of a method for BTEX determination in soil

Izvleček

Benzene, toluene, ethylbenzene and xylenes (BTEX) are environmental pollutants, that are part of the group of pollutants called volatile organic compounds (VOC). They are found in petroleum oil and are used in industry as solvents and as a precursors for synthesis of various organic compounds and materials. BTEX compounds are toxic for humans, while benzene is also cancerogenic and teratogenic. Because the smallest fraction of BTEX compounds in environment are found in water and adsorbed to soil, they need to be preconcentrated before the analysis, for which we use extraction methods, such as solid phase microextraction (SPME). In this study we developed a method for quantification of BTEX compounds in soil, for which we used SPME as an extraction method and gas chromatography coupled with mass spectrometry for analysis. In the general part extraction and chromatography methods, with the emphasis on gas chromatography and SPME are described. Furthermore results of the method optimisation are presented. Optimal conditions for separation of BTEX compounds with gas chromatography and optimal conditions for SPME are also described. The effect of type of fiber, temperature, duration of sample agitation and duration of extraction on SPME are graphically presented for each of the BTEX compounds, alongside with calibration curves. Developed method has linear concentration range from 0.5 μg/g to 5.0 μg/g. Limit of detection, which we determined experimentally, was for BTEX compounds from 12.5 ng/g to 50.0 ng/g. CAR/PDMS 75 μm fiber has proven to be the most suitable fiber for extraction of BTEX compounds using SPME. The developed method has proven to be suitable for the determination of BTEX compounds in soil and was tested on the real samples of soil, that was contaminated with diesel fuel. Besides toluene, which was present in one sample in the concentration of 0.043 μg/g, the concentrations of other BTEX compounds were below the limit of detection.

• Ključne besede: GC-MS, SPME, BTEX, VOC, environment, soil