Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Capillary electrophoresis (CE) has recently attracted considerable attention as a
promising analytical technique for the separation of cations and anions in complex
matrices. Determination of ions in aqueous samples using capillary electrophoresis
can be accomplished with indirect UV detection. Most inorganic ions have weak
absorption profiles in the UV-Vis wavelength range. These mostly non-absorbing
species are commonly detected by indirect UV absorbance through addition of an
absorbing co-ion (chromophore) into the electrolyte. Inorganic cations most often
require an additional complexing agent to selectively alter their similar mobilities and
proper separation.
For optimal determination of alkali, alkaline, and transition metal ions, several
electrolytes systems were studied. These include pyridine, imidazole and 4-
aminopyridine as UV-absorbing species and glycolic acid, a-hydroxyisobutyric acid
and their mixture were used as complexing reagents. A mixture of 10 metal ions (K+,
Na+,Ca2+, Mg2+, Mn2+, Fe2+, Cd2+, Pb2+, Ni2+and Zn2+) was successfully separated.
Detectionwas performed at 210,214 and 254 nm.
In the anion determination chromate and 2, 6 pyridine dicarboxylic acids (PDC) were
used as back ground electrolytes for inorganic ions (F-, CI- en SO₄² ̄ ) and organic
acids (tartaric acid, malic acid, succinic acid and citric acid) separations respectively.
Electroosmotic flow (EOF) was reversed in the direction of the anode by adding
Cetyltrimethylammonium bromide (CTAB) to the electrolyte. Highly alkaline
conditions were used to confer a negative charge on inorganic and organic anions to promote their migration towards the anode. The detection wavelength was 200 nm.
All peaks were completely resolved and well separated. The limit of detection (LOD)
of cations and anions were in the range of 0.5 - 3 ppm and 2 - 3.5 ppm respectively.
The described methods were used successfully in routine analysis of real samples.
This includes the qualitative and quantitative analysis of an environmental water
samples from the areas surrounding Stellenbosch, beverages and orange juice. / AFRIKAANSE OPSOMMING: Kapillêre Elektroforese (CE) het in die onlangse verlede heelwat aandag getrek as "n
belowende analitiese tegniek vir die skeiding van katione en anione in komplekse
monsters. Die bepaling van ione in waterige medium met kapillêre elektroforese word
gedoen deur indirekte Ultraviolet (UV) deteksie aangesien meeste anorganiese ione
swak absorbsie in die die sigbare UV (UV-Vis) golflengtegebied toon. Deteksie van
hierdie meestal nie-absorberende spesies word algemeen gedoen deur indirekte UV
absorbansie deur die byvoeging van "n ko-ioon (chromofoor) tot die elektroliet.
Anorganiese katione benodig dikwels "n addisionele komplekserings reagens om
selektief hulle eenderse mobiliteite te verander en sodoende goeie skeiding te
bewerkstellig.
Vir die optimale bepaling van alkali-, alkali-aard- en oorgansmetaal ione is verskeie
elektrolietsisteme bestudeer. Hierdie sluit in piridien, imidasool en 4-aminopiridien as
UV absorberende spesies en glikoliensuur, a-hydroksie-isobottersuur asook "n
mengsel van die twee as komplekserings reagense. "n Mengsel van 10 metaalione
(K+, Na+, Ca2+, Mg2+, Mn2+, Fe2+, Cd2+, Pb2+, Ni2+ en Zn2+) is sukselvol op hierdie
wyse geskei. Deteksie is gedoen by golflengtes van 210, 214 en 254 nm.
Vir die anioon bepaling is chromaat en 2,6-piridiendikarboksielsuur gebruik as
agtergrond elektroliete vir die skeiding van anorganiese anione (F-, CI- en SO₄² ̄ ) en
organiese sure (tartaarsuur, malonsuur, suksiensuur en sitroensuur), onderskeidelik.
Elektroosmotiese vloei (EOF) is omgekeer na die rigting van die anode deur
byvoeging van setieltrimetielammoniumbromied (CTAB) by die elektroliet. Sterk alkaliese kondisies is gebruik om 'n negatiewe lading op die anorganiese en
organiese anione te konsentreer en sodoende hul migrasie na die anode te bevorder.
Die deteksiegolftengte hier gebruik was 200 nm.
Volkome resolusie en goeie skeiding is gerealiseer vir al die pieke. Die
deteksielimiete (LOD) vir die katione en die anione was 0.5 - 3 ppm en 2 - 3.5 ppm,
onderskeidelik. Die metodes wat beskryf word is suksesvol aangewend vir roetiene
analise van werklike monsters. Dit sluit in kwalitatiewe sowel as kwantitatiewe analise
van omgewingswater monsters uit die Stellenbosch area, koeldranke en lemoensap.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/49989 |
| Date | 12 1900 |
| Creators | Hailemichael Goitom, Aron |
| Contributors | Crouch, A. M., Stellenbosch University. Faculty of Science. Dept. of Chemistry & Polymer Science. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 97 p. : ill., (some col.) |
| Rights | Stellenbosch University |
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