diplomsko delo
Aleš Grahovac (Author), Dorota Korte Kobylinska (Mentor)

Abstract

Srebro ima dolgo zgodovino uporabe zaradi svojega antibakterijskega učinka, vendar ga v moderni medicini srečamo predvsem pri lokalnem zdravljenju ožganin. V alternativni medicini se je za razliko prijela uporaba koloidnega srebra, to je nanodelcev srebra v vodnem koloidu, kot naravnega antibiotika. Odvisno od doze, se z uporabo lahko pojavijo tudi negativni stranski učinki, predvsem argirija, ki zaradi nalaganja srebra v tkivih povzroča sivo obarvanje kože. Zaradi tega je pomembno, da natančno nadziramo koncentracije koloidnega srebra v uporabi. V diplomskem delu smo z uporabo kemijske redukcije pripravili vzorce koloidnega srebra, katere smo uporabili za izračun meje detekcije (LOD) metod UV-VIS spektrofotometrije ter spektroskopije s toplotno lečo (TLS), tako v serijski (BM) kot pretočni (FIA) postavitvi. Sledilo je preverjanje koncentracije koloidnega in celotnega srebra v 5 komercialno dostopnih vzorcih, ter z uporabo splakovanja s kislino še možnosti nalaganja srebrovih nanodelcev na stene posode v katerih je bilo koloidno srebro shranjevano. Kot najobčutljivejša od preverjenih merilnih metod se je izkazala TLS-BM, katere LOD je bila več kot 350-krat nižji od UV-VIS spektrofotometrije (LOD (UV-VIS) = 32,00 ppb; LOD (TLS-BM) = 0,09 ppb; LOD (TLS-FIA) = 0,45 ppb). Vseh 5 preizkušenih vzorcev je imelo koncentracije koloidnega srebra nižje od navedenih na embalaži (od 32- do 283-krat nižje), koncentracije celotnega srebra pa večinoma višje od navedenih za koloidno srebro (20 % – 107 % več od navedene), po čemer lahko sklepamo, da je večina srebra v ionski obliki. Delci koloidnega srebra so se bolj nalagali na stene posod v katerih je bilo koloidno srebro hranjeno iz stekla kot iz plastike (155-317 ppb za steklo, 11-15 ppb za plastiko). TLS-BM je preprosta in učinkovita metoda za merjenje koncentracije nanosrebra v vodnem koloidu. Koncentracija srebra v testiranih vzorcih koloidnega srebra ne ustrezajo navedenim, zato velja pri nakupu večja pozornost.

Keywords

koloidno srebro;spektrofotometrija;TLS;antibiotiki;diplomske naloge;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UNG FZO - Faculty of Environmental Sciences
Publisher: [A. Grahovac]
UDC: 543.2/.9
COBISS: 4520443 Link will open in a new window
Views: 6720
Downloads: 271
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Other data

Secondary language: English
Secondary title: Determination of silver species in liquid samples
Secondary abstract: Silver has a long history of use due to its antibacterial properties, yet in modern medicine we encounter it mainly in topical burn treatment. In alternative medicine the use of colloidal silver, which is silver nanoparticles in an aqueous solution, has caught on as a natural antibiotic. Dose dependent negative side effects can arise, mainly argyria which causes grey skin pigmentation due to silver deposits in tissues. Because of this it's important to closely monitor the concentration of the colloidal silver in use. In the thesis we used chemical reduction to prepare samples of colloidal silver, with which we then calculated the limit of detection (LOD) of the UV-VIS spectrophotometric method and thermal lens spectroscopy (TLS), both in batch mode (BM) and flow injection (FIA) configurations. Afterwards we verified the concentration of colloidal and total silver in five commercially available samples and using rinsing with acid checked for possible silver nanoparticle deposits on the walls of the containers in which the colloidal silver was kept. The most sensitive of the verified methods turned out to be TLS-BM, with its LOD being over 350-times lower than that of UV-VIS spectrophotometry (LOD (UV-VIS) = 32.00 ppb; LOD (TLS-BM) = 0.09 ppb; LOD (TLS-FIA) = 0.45 ppb). All 5 tested samples had concentrations of colloidal silver lower than stated on the packaging (32- to 283-times lower) and contained concentrations of total silver mostly higher than stated for colloidal silver (20 % - 107 % higher than stated), so we can assume the majority of silver was in ionic form. Colloidal silver particles were deposited in greater quantities on the walls of containers in which colloidal silver was kept made out of glass compared to those made of plastic. (155-317 ppb for glass, 11-15 ppb for plastic). The TLS-BM method is a facile and effective method for measuring the concentration of nanosilver in an aqueous colloid. The concentration of silver in the real samples of colloidal silver do not correspond to statements, thus greater care is required when buying it.
Secondary keywords: colloidal silver;spectrophotometry;TLS;antibiotics;
URN: URN:SI:UNG
Type (COBISS): Bachelor thesis/paper
Thesis comment: Univ. v Novi Gorici, Fak. za znanosti o okolju
Pages: XI, 46 str.
ID: 9171870