Trace Element Analysis with Application to Environmental Pollutants Studies in Vietnam
Doctoral thesis, 1997
In the work presented here the attention has been focused on optimising sample preparation and analytical techniques for trace element determination, analytical quality assurance and environmental applications.
Trace element concentrations in various environmental matrices were investigated using Energy Dispersive X-ray Fluorescence (EDXRF), Inductively Coupled Plasma Mass Spectro-metry (ICP-MS) and Cold Vapour Atomic Absorption Spectrometry (CV-AAS). Using microwave digestion, a H2SO4/HNO3/H2O2 acid mixture was found to be optimal for the complete mineralisation and digestion of biological samples for Hg analysis by CV-AAS, whereas for EDXRF and ICP-MS analysis, the HNO3/H2O2 acid mixture gave good results.
A set of eleven standard reference samples was used to evaluate the analytical procedures. A good agreement was obtained between the different analytical methods used. The results obtained were also in good agreement with certified values. Samples were collected in the immediate surroundings of industrial areas and coal mines. Trace element concentrations were also determined in the urine, blood and hair of industrial workers and children in Vietnam.
In one of the applications, a positive correlation was obtained between the content of Pb in the urine of Pb exposed workers and Pb in the indoor air. The urine Pb levels correlated well with the urine levels of Rb, Cu, Zn, Fe and K. In the study of children with convulsions, prolonged diarrhoea and malnutrition, the most elevated trace element concentration observed in the blood was Pb. One possible explanation was found in another study where the high Pb content in Al alloy pots significantly contaminated the boiled rice cooked in them. Children fed with rice cooked in these pots were affected clinically.