Analysis of trace mercury in water by solid phase extraction using dithizone modified nanometer titanium dioxide and cold vapor atomic absorption spectrometry

A new method for analysis of trace mercury in water samples was developed, based on the combination of preconcentration/separation using dithizone-modified nanometer titanium dioxide （TiO2） as a solid phase extractant and determination by cold vapor atomic adsorption spectrometry （CVAAS）. Dithizone was dissolved with alcohol and loaded on the surface of nano-sized TiO2 powders by stirring. The static adsorption behavior of Hg^2＋on the dithizone-modified nanoparficles was investigated in detail. It was found that excellent adsorption ratio for Hg^2＋ could be obtained in the pH range of 7-8 with an oscillation time of 15 rain, and a 5 mL of 3.5 mol·L^-1 HCI solution could quantitatively elute Hg^2＋ from nanometer TiO2 powder. Common coexisting ions caused no obvious influence on the determination of mercury. The mechanisms for the adsorption and desorption were discussed. The detection limit （30） for Hg^2＋ was calculated to be 5 ng·L^-1. The proposed method was applied to the determination of Hg^2＋ in a mineral water sample and a Zhujiang River water sample. By the standard addition method, the average recoveries were found to be 94.4%-108.3% with RSD （n = 5） of 2.9%-3.5%.

Monitoring of Environmental Mercury Exposure Using Hair as Bioindicator and the Study of Potential Factors Affecting on It in Karachi

The World Health Organization (WHO), Environmental Protection Agency (EPA), and International Atomic Energy Agency (IAEA) have recommended the use of hair for worldwide environmental monitoring. Mercury exposure to the inhabitants of Karachi was assessed by using hair as bioindicator. Hair samples of 200 residents of Karachi were collected and analyzed through cold vapor atomic absorption spectroscopy (CVAA) technique for mercury concentration. The effects of age, gender, working status, location, food and smoking habit were investigated. Control region showed a positive correlation between HHg and age of donor while no such correlation was observed for polluted regions. Mercury exposure through cosmetic usage in female was only pronounced in control region. These results indicate that environmental pollution dominates other potential factors. Age and smoking habit were not found to be the influencing factors while an elevated mean level of mercury was noticed for regular fish consumers than rarely fish consumers. 95.33% of the samples contained HHg greater than the permissible level of 2 μg?g?1 set by WHO. An apparently healthy male donor had HHg concentration (28.24 μg?g?1) closer to the high risk concentration of 30 μg?g?1 based on WHO criteria. Whereas, two female donors of the age group of 41-50 years had HHg concentrations (10.82 and 11.84 μg?g?1) higher than the NOAEL (no observed adverse affects level) value (10 μg?g?1) for females which is associated with fetus neurotoxicity. However, no symptoms of mercury toxicity were visible. The results indicate the alarming condition of pollution in the city which should be taken into further consideration.