Ustvarjanje koncentracijskega gradienta v pretočnem sistemu in analizna uporaba

Marolt, Špela (author), Gros, Nataša (mentor)

Pri magistrskem delu smo v pretočnem sistemu ustvarjali koncentracijski gradient z uporabo dveh črpalk z nameščenima brizgama. Tovrstne črpalke omogočajo funkcije, s pomočjo katerih smo uspeli nastaviti programa za doseganje linearnega in eksponentnega gradientnega profila. Pretok prve črpalke se je s časom linearno/eksponentno povečeval od nič do maksimalne vrednosti, medtem ko se je pri drugi črpalki linearno/eksponentno zmanjševal od maksimalne vrednosti do nič. Ustreznost nastavljenih programov smo preverili s potiskanjem vode skozi sistem in nato še dveh barvil z različnim absorpcijskim maksimumom. Skladno s tem smo definirali pogoje za izvedbo titracije. Z gradientnim načinom v pretočni analizi vodimo reakcije. Primer titracije, ki smo jo spremljali spektrometrično, je reakcija Cu(II) z raztopino dinatrijeve soli EDTA, pri kateri nastane modro obarvan produkt, ki močneje absorbira svetlobo kot raztopina bakrovih ionov. Rezultati titracij so odvisni od koncentracijskega območja analitov in razmerij s titrirnim sredstvom, ki se tvorijo v pretoku pri različnih načinih zagotavljanja gradienta. Potrdili smo oblikovne razlike v FIA-gramih, dobljenih za različne koncentracije Cu(II) pri uporabi eksponentnega oz. linearnega gradientnega programa. Izvedli smo tudi gradientno titracijo Cu(II) z raztopino dinatrijeve soli EDTA, in sicer na dva načina. Najprej smo izmenično potiskali Cu(II) in raztopino dinatrijeve soli EDTA, nato pa smo v neprekinjen tok raztopine dinatrijeve soli EDTA potiskali Cu(II). V prvem primeru smo prišli do zaključka, da maksimum krivulje za produkt pri večjem volumskem paketu Cu(II) nastopi kasneje, v drugem primeru pa se ob spremenjeni obliki krivulje maksimum zviša.

• Language: Slovenian
• Keywords: koncentracijski gradient, pretočna injekcijska analiza, titracija v pretočnem sistemu, Cu(II), EDTA
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2022
• PID: 20.500.12556/RUL-134904
• COBISS.SI-ID: 98020611
• Publication date in RUL: 10.02.2022

MAROLT, Špela, 2022, Ustvarjanje koncentracijskega gradienta v pretočnem sistemu in analizna uporaba [online]. Master’s thesis. [Accessed 30 May 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=134904

Secondary language

• Language: English
• Title: Generation of concentration gradient in flow-injection system and analitical applications

Abstract

In the master's thesis we created a concentration gradient in the flow-injection system by using two syringe-based pumps. Such pumps enable functions, which helped us to set programs to achieve a linear and exponential gradient profile. Flow rate of the first pump increased linearly/exponentially from zero to maximum value, while on the second pump flow rate decreased linearly/exponentially from maximum value to zero. Suitability of the set programs was checked firstly by pushing water through the system and secondly by pushing two dyes with different absorption maximum. Accordingly, we defined the conditions for titration. Reactions are controlled by gradient mode in flow analysis. The model titration which we monitored spectrometrically was the Cu(II)-EDTA disodium salt solution reaction producing a blue-colored product that absorbs more light than the solution of Cu(II). The titration results depend on the concentration range of the analytes and the ratios with the titrant that are formed in the flow by different gradient modes. We confirmed the shape differences in FIA-grams obtained for different concentrations of Cu(II) using exponential/linear gradient program. We further performed a gradient titration of Cu(II) with EDTA disodium salt solution in two different ways. First, Cu(II) and EDTA disodium salt solution were pushed alternately and second, Cu(II) was pushed into the continuous flow of EDTA disodium salt solution. In the first case we came to the conclusion that maximum of the curve for the product is shifted towards later times with increase in volume of Cu(II), in contrast to the second case, in which the maximum rises while the shape of the curve changes.

• Keywords: concentration gradient, flow injection analysis, titration in flow-injection system, Cu(II), EDTA