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Oulun yliopiston väitöskirjat

TRACE ELEMENT ANALYSIS OF HUMUS-RICH NATURAL WATER SAMPLES, ACTA UNIVERSITATIS OULUENSIS A Scientiae Rerum Naturalium 697

ISBN-10:	978-952-62-1680-5
Kieli:	englanti
Kustantaja:	Oulun yliopisto
Oppiaine:	Luonnontiede
Painos:	Osajulkaisuväitöskirjan yhteenveto-osa
Painosvuosi:	2017
Sijainti:	Print Tietotalo
Sivumäärä:	62
Tekijät:	HAVIA JOHANNA

15.50 €

Humus-rich natural water samples, containing high concentrations of dissolved organic carbon (DOC), are challenging for certain analytical methods used in trace element analysis, including hydride generation methods and electrochemical methods. In order to obtain reliable results, the samples must to be pretreated to release analytes from humic acid complexes prior to the determination. In this study, methods for both pretreatment and analysis steps were developed. Arsenic is a toxic element and therefore its determination even at low concentration levels is important in environmental monitoring. Arsenic complexed with humic substances is not likely to form volatile hydrides quantitatively during borohydride reduction. In this study, natural water samples were digested with microwave-assisted digestion method prior to analysis by hydride generation inductively coupled plasma mass spectrometry (HG-ICP-MS). In addition, a dual mode sample introduction system was used to study internal standardization in order to correct signal variations during the measurement of arsenic with HG-ICP-MS. A novel nano-TiO2 catalyzed ultraviolet light emitting diode (UV-LED) digestion device was developed to apply green chemistry principles in sample preparation. The method consumes less harmful reagents and less energy than traditional techniques. The DOC removal efficiency was studied as a function of pH, irradiation time and hydrogen peroxide concentration. Recoveries of spiked heavy metals and hydride forming elements were studied. UV-LED technology is growing rapidly, and new catalytic semiconductor materials for photocatalysis are being developed. In this study, the effects of synthesis method variables on the properties of ZnO nanopowders were investigated.

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