Fluorescence detection of trace aluminium using a sequential injection analyser

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dc.contributor.advisorRoychoudhury, Alakendra N.en_ZA
dc.contributor.advisorSamanta, Saumiken_ZA
dc.contributor.authorDe Jongh, Taraen_ZA
dc.contributor.otherStellenbosch University. Faculty of Science. Dept. of Earth Sciences.en_ZA
dc.date.accessioned2022-11-06T15:32:58Z
dc.date.accessioned2023-01-16T12:42:00Z
dc.date.available2022-11-06T15:32:58Z
dc.date.available2023-01-16T12:42:00Z
dc.date.issued2022-12
dc.descriptionThesis (MSc)--Stellenbosch University, 2022.en_ZA
dc.description.abstractENGLISH ABSTRACT: Analytical instruments are either expensive to operate, prone to interferences, require a separate offline preconcentration step, or are not suitable for use onboard a ship when measuring dissolved Aluminium (Ald; < 0.2 µm fraction) in seawater. Thus far, Ald measurements have been performed most commonly using flow injection analysis (FIA), as it combines preconcentration, fluorometry and spectroscopy in a single manifold. Despite FIA’s compact and comprehensive design, the manifold has several drawbacks, including its laminar flow regime and the peristaltic pump, which causes tube stretching and generates measurement drift. As a result of these limitations, a third-generation flow analyser was developed, known as a miniaturized two-line sequential injection analyser (miniSIA-2). The miniSIA-2 incorporates similar design features to that of FIA, however, it operates on a bidirectional flow regime, enabling reverse fluid flow and encourages turbulence to allow complete sample and reagents reaction, while reducing the reagent consumption and waste generation. Thus far, the miniSIA- 2 has only been used to measure trace concentrations of Zinc (Zn) (Grand et al., 2011; Grand et al., 2016) and Iron (Fe) (Oliveira et al., 2015; Hatta et al., 2018) in seawater. This project therefore involves a novel and systematic approach to measuring Ald in seawater through fluorescence detection by an advanced miniSIA-2 manifold of Grand et al., (2016). The systematic approach involved integrating the experimental procedures outlined by Hatta et al., (2018) and the experimental protocols of Grand et al., (2011 & 2016) first and second design of Znd for measurements of Ald. This led to a method approach initiated with optimizing the batch method, followed by the Stop in Holding coil (SHC) procedure and finally incorporating a Solid Phase extraction (SPE) step with the SHC to ensure a fully automated instrument for measuring Ald in seawater. However, this project focused on developing and applying the well- established batch method from Hydes & Liss, (1976). The method details the development of a two-step method. Initially, a basic analytical setup was established by systematically adjusting parameters to achieve measurements at relatively higher Ald concentrations. During this step, a limit of detection (LOD = 9 nM) was achieved. The above-mentioned analytical setup was then used to achieve instrumental detection limits similar to the lowest Ald concentrations measured in global oceans (0.1 nM). In this second instant a lower LOD (7 nM) was achieved, however, the improvement was much less than the initial aim. This was the result of the instruments fluctuating baseline values, high Relative Standard Deviation (RSD), and the manifold’s inability to self-regulate internal temperatures during analysis time causing a weak peak configuration that resembled that of photobleaching and quenching.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Analitiese gereedskap is gewoonlik duur om te gebruik, sensitief vir inmenging of benodig ‘n voorkonsentrasie proses wanneer dit kom by die meet van opgelosde aluminium (Ald < 0.2 µm fraction) in seewater. Tot dusver word vloei inspuiting analiese (FIA) verkies om Ald in seewater te meet omdat dit die voorkonsentrasie, flourometrie en spektroskopie in ‘n enkel manifold kombineer. Ten spyte van FIA manifold kompakte en omvattende ontwerp, die manifold het verskeie nadele, insluitend die laminêre vloei regime en die peristaltiese pomp wat die vloei aandryf en die pype kan strek en dus en metingsdrywing genereer. As gevolg van hierdie beperkings, het die derde generasie van flow analiseerders tot weeg gebring wat bekend staan as die miniSIA-2 (miniatuur twee-lyn opeenvolgende inspuitings analiseerder). Die miniSIA-2 bevat soortgelyke ontwerpkenmerke van dit van FIA, maar werk op en tweerigting- vloeiregime, wat omgekeerde vloeistofvloei moontlik maak en turbulensie aanmoedig om volledige monster-en reagensreaksie toe te laat,terwyl die reagensverbruik en afvalgenerering verminder word. So vêr, was die miniSIA-2 voorheen gebruik om die konsentrasie Zink (Zn) (Grand et al., 2011; Grand et al., 2016) en Yster (Fe) (Oliveira et al., 2015; Hatta et al., 2018) in seewater te meet. Hierdie projek behels dus ń nuwe en sistematiese benadering om Ald in seewater te meet deur fluoressensie-opsporing deur ń gevorderde miniSIA-2 spruitstuk van Grand et al., (2016). Die sistematiese benadering behels die integrasie van die eksperimentele prosedures soos uiteengesit deur Hatta et al., (2018) en die eksperimentele protokolle van Grand et al., (2011 & 2016) eerste en tweede ontwerp van Znd vir metings van Ald. Dit het gelei tot ń metodebenadering wat begin het met die optimering van die “Batch”-metode, gevolg deur die “Stop in Holding-spoel” (SHC)-prosedure en uiteindelik ń “Solid Phase-ekstraksie- stap (SPE) by die SHC ingesluit het om ń ten volle outomatiese instrument vir Ald in seewater te verseker. Weens tydsbeperkings het hierdie projek egter gefokus op die ontwikkeling en toepassing van die goed gevestigde “Batch”-metode van Hydes & Liss, (1976). Die metode beskryf die ontwikkeling van ń twee-stap metode. Aanvanklik was ‘n basiese opstelling ontwikkel deur sistematies die parameters te verander vir relatiewe hoë Ald waardes. Gedurende hierdie fase, was die laagste konsentrasie Ald wat beroubaar opgespoor kon word in die oplossing, 9nM. Die bogenoemde analitiese opstelling was toe uitgebrei om aluminium te kan meet tot die laagste Ald konsentrasie wat in die wêreld se oseane gemeet word (0.1 nM). In hierdie geval was die laagste konsentrasie wat gemeet kon word, 7 nM. Die 7 nM Ald is veel meer as die 0.1 nM waarvoor gemik was. Die rede vir hierdie tekortkoming was die wisselvallige grondvlak waardes, hoë Relatiewe standaardafwyking (RSD) waardes en die manifold se onvermoë om die temperatuur te reguleer. Hierdie het ‘n onbetroubare piek in die gemete grafiek teweeg bring wat “photobleaching” en “quenching kan voorstel.af_ZA
dc.description.versionMastersen_ZA
dc.format.extentxv, 91 pages : illustrations (some color)en_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/125935
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subjectDissolved Aluminium -- Analysisen_ZA
dc.subjectSequential injection analysisen_ZA
dc.subjectTrace elements -- Detectionen_ZA
dc.subjectFluorescence detectionen_ZA
dc.subjectTrace elements in water -- Environmental aspectsen_ZA
dc.subjectUCTDen_ZA
dc.titleFluorescence detection of trace aluminium using a sequential injection analyseren_ZA
dc.typeThesisen_ZA
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