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PubMed2004

Separation and determination of lanthanides, thorium and uranium using a dual gradient in reversed-phase liquid chromatography.

Separation and determination of lanthanides, Th and U is of great relevance in different fields of science and technology. Reversed-phase high-performance liquid chromatography (RP-HPLC) using alpha-hydroxy isobutyric acid (alpha-HIBA) as an eluent on reversed-phase column modified to cation exchanger has been reported to achieve the separation. However, under those conditions, Th and U are eluted amongst lanthanides, making their quantification difficult due to overlapping with some of the lanthanides peaks. In this work, different chromatographic parameters (concentrations of eluent and ion interaction reagent, pH, etc.) were studied systematically to arrive at optimum chromatographic conditions. Using the dual (concentration and pH) gradient conditions, lanthanides, Th and U could be separated in 11 min by RP-HPLC with sequential elution of Th and U after the elution of all the lanthanides. The separation methodology was tested using SY-3 rock sample for the separation and determination of lanthanides, Th and U. The method allows an accurate determination of these elements in a single run using a single column. Also, the method is fast and cost-effective compared to the reported methods.

Butyrates↗
PubMed2004

Uranium-238 and thorium-232 series concentrations in soil, radon-222 indoor and drinking water concentrations and dose assessment in the city of Aldama, Chihuahua, Mexico.

High-resolution gamma spectrometry was used to determine the concentration of 40K, 238U and 232Th series in soil samples taken from areas surrounding the city of Aldama, in Chihuahua. Results of indoor air short-time sampling, with diffusion barrier charcoal detectors, revealed relatively high indoor radon levels, ranging from 29 to 422 Bq/m3; the radon concentrations detected exceeded 148 Bq/m3 in 76% of the homes tested. Additionally, liquid scintillation counting showed concentrations of radon in drinking water ranging from 4.3 to 42 kBq/m3. The high activity of 238U in soil found in some places may be a result of the uranium milling process performed 20 years ago in the area. High radon concentrations indoor and in water may be explained by assuming the presence of uranium-bearing rocks underneath of the city, similar to a felsic dike located near Aldama. The estimated annual effective dose of gamma radiation from the soil and radon inhalation was 3.83 mSv.

Air Pollutants, Radioactive↗
PubMed2002

Direct quantification of human serum albumin in human blood serum without separation of gamma-globulin by the total internal reflected resonance light scattering of thorium-sodium dodecylbenzene sulfonate at water/tetrachloromethane interface.

A direct quantification of human serum albumin (HSA) in blood serum samples without separation is proposed based on the measurements of total internal reflected resonance light scattering (TIR-RLS) at water/tetrachloromethane (H(2)O/CCl(4)) interfaces. In the pH range of 6.37-6.59, the coadsorption of the binary complex of HSA-Th(IV) with sodium dodecylbenzene sulfonate occurs at the H(2)O/CCl(4) interface, forming an amphiphilic layer and displaying greatly enhanced TIR-RLS signals with the maximum peak located at 340-370 nm. The enhanced TIR-RLS intensity is in proportion to the HSA concentration in the range 0.15-1.0 micro gml(-1). The limit of detection is 14.4 ngml(-1). The contents of HSA in blood serum samples were determined with the recovery of 97.1-102.3% and RSD of 0.6-2.9%, which are identical to those obtained according to the spectrofluorimetric method using chrome azurol S.

Benzenesulfonates↗
PubMed2004

Thorium and uranium contents in human urine: influence of age and residential area.

Inductively coupled plasma mass spectrometry (ICP-MS) has been used for the determination of (232)Th and (238)U in urine of unexposed Jordanian subjects living in six cities. The range of (232)Th excretion in all subjects was found to be 1.4-640 microBq d(-1) with an average of 34.8 microBq d(-1) (geometric mean 15.8 microBq d(-1)). Results showed no statistically significant correlation with age and residential area. The average value obtained is in agreement with levels considered normal in some recent publications. The average value of (238)U in all samples was found to be 3955 microBq d(-1) (geometric mean 1107 microBq d(-1)), which is higher than reported figures from Germany and India, but in agreement with those figures given in ICRP publication, number 23. The mean values of the different groups were found to be proportional to age up to 60 years. A noticeable drop is observed for subjects greater than 60 years old.

Adolescent↗
PubMed2000

Uranium-thorium levels in the sediments of the Kubanni River in Nigeria.

U-Th levels of the Kubanni River sediments in the Nigerian Basement Complex have been determined and shown to be enriched with mean values of 9.06+/-2.66 and 21.44+/-4.12 (ppm) respectively. The probable contributory factors are either phosphate fertilisers used on the neighbouring farms or low aeolian depositions from the NE trade winds blowing from the Sahara desert across the Northern Nigeria Savannah region. The other major contributing factor is the annual weathering of the basement granites. This work revealed more clustering of our data sets below the igneous line as proposed by other authors.

Fresh Water↗