Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: selective determination

Sortuj według:

Ogranicz wyniki do:

Electrochemical Behavior of Ascorbic Acid and Uric Acid in the Presence of Micelles and Their Selective Determination Application

Gao Z., Peng J., Han X.

Polish Journal of Chemistry

2007

Vol. 81, nr 3

441-454

The electrochemical behavior of ascorbic acid (AA) and uric acid (UA) in both aqueous cetylpyridinium bromide (CPB) and sodium dodecyl benzene sulfonate (SDBS) micellar solutions have been studied by cyclic voltammetry. The oxidation peak potentials shift more negatively, and the peak currents increase in aqueous CPB micellar solutions for AA and UA. However, the oxidation peak potentials shift more positively, and the peak currents decrease in aqueous SDBS micellar solutions for AA and UA. Therefore, CPB can enhance the electrochemical oxidation reaction for AA and UA, and SDBS hinders the electrochemical oxidation reaction. The electrochemical kinetic parameters for AA and UA in both aqueous CPB and SDBS micellar solutions are determined by chronocoulometry (CC) and chronoamperometry (CA). The charge transfer coefficients _ and the electrode reaction rate constants kf for AA and UA are enhanced in aqueous CPB micellar solutions, but reduced in aqueous SDBS micellar solutions. The pulse differential voltammetric behavior for AAand UAare also investigated in this work. The experimental results show that the oxidation peak potentials forAAandUAare separated by 270mVin the presence ofCPB in aqueous PBS (phosphate buffer solution, pH 6.8) solutions. Thus, AA and UA can be selectively determined in aqueous CPB micellar solutions, especially selectively determination of UA in the presence of excess of AA is possible. According to our work, the practical application of the results can be used to determineUAin human urine and serum samples, the determination results are satisfied.

Preconcentration of ultra-trace amounts of copper(II) applying solid phase extraction on novel octadecyl silica-modified membrane discs

Shamsipur M., Saeidi M., Sharghi H.

Chemia Analityczna

2005

Vol. 50, No. 6

1051-1058

A simple and reliable method for selective separation and preconcentration of trace amounts of Cu(II) ions from aqueous samples has been developed. Aqueous samples were passed through octadecyl silica membrane disc modified with a recently synthesised phenol-derivative Schiff's base. Cu2+ ions were adsorbed quantitatively. Almost all matrix components were passed through the disc. Retained Cu2+ ions were eluted from the disc using a minimum amount of hydrochloric acid as an eluent. They were subsequently determined applying atomic absorption spectrometry. Enrichment factors achieved in the proposed method were of about 200 and higher. Detection limit equalled 30 ng of Cu2+ per 1000 mL. The influence of various cationic interferences on the recovery of Cu:2+ ions in binary mixtures was studied, The method was applied to the recovery studies of Cu2+in synthetic samples and tap water.

Opracowano prosta, i niezawodną metodę selektywnego wydzielania i zatcżania śladowych ilości jonów Cu(II) z próbek wodnych. Próbki wody przepuszczano przez dysk membranowy 7. fazą związaną C ]S modyfikowany nowo zsyntezowaną zasadą Schiffa, pochodną fenolu. Jony Cu2+ byiy adsorbowane ilościowo, a pozostałe składniki matrycy prawie wszystkie przechodziły przez dysk. Zatrzymane jony Cu2+ eluowano z dysku małą ilością kwasu solnego i oznaczano za pomocą absorpcyjnej spektrometrii atomowej. Otrzymane współczynniki zateżania wynosiły 200 i więcej. Granica wykrywalności wynosiła 30 ng Cu:2+ w 1000 mL. Badano wpływ różnych interferentów kationowych na odzysk jonów Cu:2+ z mieszanin dwuskładnikowych. Opracowaną metodę zastosowano do badania odzysku Cu:2+ z próbek syntetycznych i wody pitnej.