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Determination of oxygen by means of a biogas and gas - interference study using an optical tris (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride complex sensor
Polona Brglez, Andrej Holobar, Aleksandra Pivec, Nataša Belšak, Mitja Kolar, 2012, original scientific article

Abstract: Biogas is a mixture of gases produced by anaerobic fermentation where biomass or animal waste is decomposed and methane and carbon dioxide are mainly released. Biogas also has a very high moisture content (up to 80%), temperatures of around 60 °C, high pressure, and can contain other gases ($N_2$, $H_2S$, $NH_3$ and $H_2$). We searched for an appropriate measuring system for the determining of oxygen in biogas, since the production process of biogas must be run under anaerobic conditions; as the presence of oxygen decreases the quality of the biogas. Ruthenium (II) complexes are by far the most widely-used oxygen dyes within optical oxygen sensors. In general, they have efficient luminescences, relatively long-life metal-ligand charge-transfer excited states, fast response times, strong visible absorptions, large Stokes shifts, and high-photochemical stability. The purpose of this work was to characterise and optimize an optical oxygen sensor using tris (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride complex for measuring oxygen. Different sensor properties were additionally studied, focusing on the interference of external light, temperature, and various gases. A special gas-mixing chamber was developed for gas interference study, and online experiments are presented for oxygen determination within the pilot biogas reactor.
Keywords: tris(4, 7-diphenyl-1, 10-phenanthroline)ruthenium(II) dichloride complex, oxygen optical sensor, interferences, biogas
Published: 01.06.2012; Views: 1188; Downloads: 39
.pdf Full text (315,15 KB)

Spin-coating for optical-oxigen-sensor preparation
Polona Brglez, Andrej Holobar, Aleksandra Pivec, Mitja Kolar, 2014, original scientific article

Abstract: Thin-film oxygen sensors were prepared using the spin-coating technique, where a tris (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride complex (RuDPP) in various solvents and silicones deposited on different substrates was used for the sensor production. By changing the spin-coating set-up parameters, homogeneous sensor coatings and the optimum sensor response to oxygen were studied – the sensors were exposed to various concentrations of oxygen within the range from 0% to 100 %. During the presented study, the optimum results were obtained when a 150 µL of sensor solution was applied to a Dataline foil using silicone E4 and a chloroform solvent. A spin coater with the following three rotation stages was used: 750/700 r/min for 3 s, 300 r/min for 3 s and 150 r/min for 4 s. The spin-coating technique has several benefits: it is fast, easy to use and appropriate for low-volume operations. It allows modifications and preparations of several sensor series using the minimum reagent consumption. However, the disadvantage of this technique also has to be mentioned, namely, an uneven film thickness in the radial direction. The film thickness mainly depends on the experimental set-up (volume, rotation time and speed, solvent viscosity and evaporation). Spin coating as an alternative and very flexible technique for an oxygen-sensor preparation is suggested for the laboratory-scale work, where the majority of experimental data could be used when other new coating methods are also researched and implemented.
Keywords: optical sensors, spin coating, oxigen
Published: 21.12.2015; Views: 543; Downloads: 38
.pdf Full text (254,63 KB)

Razvoj in validacija plinskih senzorjev za medicinske aplikacije
Evelina Mohorko, 2016, master's thesis

Abstract: V sklopu magistrske naloge smo preučevali razvoj in validacijo analizatorja E-NH3 V1.2 za določanje amoniaka v izdihanem zraku zdravih posameznikov in pacientov s kronično ledvično boleznijo (KLB). Merilni postopek in delovanje analizatorja E-NH3 V1.2 smo tudi delno validirali, z namenom potrditve ustreznosti. Določili smo linearnost (R2 = 0,9969), ponovljivost (RSD ≤ 1,5%), mejo zaznavnosti (0,7 ppm) in mejo določljivosti (2,5 ppm). Sledile so analize realnih vzorcev. V raziskavo smo vključili zdrave posameznike in paciente s kronično ledvično boleznijo (KLB), ki so ustrezali določenim kriterijem. Pri primerjavi koncentracij amoniaka v izdihanem zraku zdravih posameznikov in pacientov s KLB, smo ugotovili statistično signifikantno razliko med skupinama. Povprečna koncentracija amoniaka v izdihanem zraku zdravih posameznikov je bila < LOQ in pri pacientih s KLB 4 ppm. Ugotovili smo, da je koncentracija amoniaka v izdihanem zraku verjetno povezana s kronično ledvično boleznijo, vendar so potrebne dodatne klinične raziskave na večji populaciji vzorcev izdihanega zraka zdravih posameznikov in pacientov s KLB. Preizkusili smo tudi delovanje detekcijskih cevk za določitev amoniaka v zraku in pretočni injekcijski sistem. Korelacija med analizatorjem E-NH3 V1.2 in detekcijskimi cevkami je bila zadovoljiva. Injekcijski sistem za določanje amonijevega iona smo modificirali in preizkusili, ali bi ga lahko uporabili pri analizi amoniaka v izdihanem zraku. Ugotovili smo, da je bilo uvajanje plinastega amoniaka (4 ppm) v borovo kislino učinkovito. Uporabljen sistem sicer ni primeren za analizo izdihanega zraka v bolnišnicah, zaradi kompleksnosti izvedbe analiz in toksičnih kemikalij.
Keywords: amoniak, analiza izdihanega zraka, elektrokemijski senzor, kronična ledvična bolezen
Published: 03.02.2016; Views: 897; Downloads: 150
.pdf Full text (3,05 MB)

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