Chemometrics aided energy dispersive X-ray fluorescence and scattering for diagnostic modeling of trace biometals as cancer biomarkers.

Direct analysis of biometals in biomedical samples by energy dispersive X-ray fluorescence (EDXRF) for disease diagnostics has hardly been fully explored due to dark matrix analytical challenges. In this study, we exploited multivariate chemometrics modeling of cancer diagnostics in model human tissue simulates and cultures using selected biometals' (Mn, Fe, Cu, Zn and Se) fluorescence and Compton scatter profiles. PCA successfully reduced the correlated data dimension to uncorrelated datasets for the characterization of the cell cultures. Artificial neural network (ANN) enhanced the classification of cancer staging and the development of a multivariate calibration strategy for the quantification of trace elements. ANN characterized cancer into early, intermediate, and advanced stages of development. Low concentrations of Fe (101 ± 28 ppm), Zn (59 ± 4 ppm) and Cu (21 ± 1 ppm) were evident in SV10 due to the lag phase stage of cancer development. Further, strong correlation (0.976) was evident in early-stage cancer between Zn and Se but with strong negative correlations between Mn and Se (-0.973) and between Mn and Zn (-0.900) probably due to their antioxidant effects. The results show predictable and systematic associations between the concentrations of Fe, Cu, Zn, Se and Mn as cancer biomarkers with the potential to be used for cancer diagnosis at the early stage of development.

Direct rapid quality assurance analysis of complex matrix materials: A chemometrics enabled energy dispersive X-ray fluorescence and scattering spectrometry application.

Compared to energy dispersive X-ray fluorescence (EDXRF) that is limited to analysis of elements (Z ≥ 13) via fluorescence and which is hardly direct, energy dispersive X-ray fluorescence and scattering (EDXRFS) spectrometry exploits additionally, scatter radiation to quantify both low- and heavy-Z elements as well as predict various material properties. The goal of this work was to demonstrate proof-of-concept for chemometrics-enabled EDXRFS spectrometry utilizing a weak sample excitation source towards rapid quality assurance (QA) analysis of complex matrix materials. A109Cd source was used to analyse three types of polymer powders - polypropylene (PP), low density polyethene (LDPE) and high density polyethene (HDPE) moulded as âˆ¼ 2.5 g (∅ = 2.5 cm) pellets; and both actual as well as simulate lubricating oils spiked with trace additive metals B, Na, Ca, Mg, Fe and Zn and subjected to thermal degradation between 100 °C and 400 °C for 24 h. EDXRFS combined with principal components analysis (PCA) and soft independent modelling of class analogy (SIMCA) accurately identified polypropylene as well as differentiated it from both low density polyethene (LDPE) and high density polyethene (HDPE). LDPE and HDPE were fairly discriminated on the basis of density. In the second application partial least squares (PLS) modelling successfully determined the viscosity of lubricating oils utilizing the combination of the scatter peak and the Zn fluorescence signature, as well as correlated the lubricating oils viscosity to their thermal degradation. The reported method is applicable in industrial quality assurance due to its non-destructivity and speed.

Rapid in-situ radiometric assessment of the Mrima-Kiruku high background radiation anomaly complex of Kenya.

This paper presents the radiometric survey results of the Mrima-Kiruku high background radiation (HBR) anomaly complex of south coastal Kenya. Utilizing a portable γ-ray spectrometer consisting of a 2.0 l NaI(Tl) backpack detector integrated with GPS to perform the relevant in-situ radiometric measurements, a novel geospatial gating method was devised to represent the measurements. The goal of this study was to assess radiation exposure and associated natural radioactivity levels in the complex and to compare the results obtained with those from previous preliminary related studies. Absorbed dose-rates in air were found to range <60-2368 nGy h-1. These rates were observed to correspond with the spatial variability of the underlying geology and terrain, increasing toward the summits of both Mrima and Kiruku Hills which implies that the complex is a geogenic HBR anomaly. The activity concentrations of 232Th in the study area are generally higher than those of 40K and 238U: The means of 40K, 238U and 232Th ranged 235±19-603±28 Bq kg-1, 68±6-326±24 Bq kg-1 and 386±12-1817±51 Bq kg-1 respectively. It was concluded that the high air absorbed dose-rate values that were measured (>600 nGy h-1) are due to elevated activity concentrations of 232Th. Therefore there is significant (>1 mSv/y) radiological hazard to the inhabitants of the area particularly those who reside at the foothills of both Mrima and Kiruku Hills.

Natural radioactivity and external dose in the high background radiation area of Lambwe East,Southwestern Kenya.

Absorbed dose rates around the North and South Ruri hills in Lambwe east, southwestern Kenya were measured using survey meters. The area lies roughly between latitudes 0°30'S and 1°00'S. It is bounded on the east by longitude 34°30'E and on the west by the shores of Lake Victoria and Winnam Gulf. The measured absorbed dose varies from 0.7 to 6.0 µGy h(-1), and the mean is 2.3 µGy h(-1). Assuming an outdoor occupancy factor of 0.4, the corresponding range and mean annual effective doses are 1.7-14.7 and 5.7 mSv, respectively. The average activity concentrations (ACs) of (232)Th, (226)Ra and (40)K in samples of soils and rocks from the area are 1397, 179 and 509 Bq kg(-1), respectively. Values of absorbed dose rates calculated from the ACs are general lower than those obtained from in situ measurements. Possible causes of these discrepancies were discussed in the paper.

Energy dispersive X-ray fluorescence analysis of mine waters from the Migori Gold Mining Belt in Southern Nyanza, Kenya.

Analyses of water samples from Mikei, Osiri, Masara and Macalder (Makalda) gold mines of the Migori gold mining belt of Southwestern Kenya were done to determine the level of heavy metals using the Energy Dispersive X-ray Fluorescence technique. The concentrations of the heavy metals were; copper (29.34 ± 5.01-14,975.59 ± 616.14 µg/L); zinc (33.69 ± 4.29-683.15 ± 32.93 µg/L); arsenic (958.16 ± 60.14-18,047.52 ± 175.00 µg/L) and lead (19.51 ± 5.5-214.53 ± 6.29 µg/L). High levels of arsenic and lead were noted. These heavy metals are not only dangerous to the lives of miners and the local inhabitants; they are also a threat to aquatic life since these waters finally find their way into Lake Victoria.

Radiological survey and assessment of associated activity concentration of the naturally occurring radioactive materials (NORM) in the Migori artisanal gold mining belt of southern Nyanza, Kenya.

A radiological survey and assessment was carried out at selected sites (Osiri, Mikei, Masara and Macalder) in the Migori gold mines of southern Nyanza, Kenya to determine the levels of exposure of the artisanal miners to the naturally occurring radioactive materials (NORM) and dust. The activity concentrations of (40)K and the decay products of (232)Th and (226)Ra were obtained using an innovative method in single channel NaI(Tl) gamma-ray spectrometry. The counts for both the sample and the reference material in a specific window for a particular radionuclide were compared to arrive at the activity concentration of the radionuclide in the sample. Measurement of dust loading at various crushing sites was carried out by trapping the dust particles on a 0.45 µm cellulose acetate filter paper (47 mm diameter) using a vacuum pump. The activity concentration levels range widely 80-413, 12-145 and 21-258 Bq/kg for (40)K, (232)Th and (226)Ra, respectively. The calculated absorbed dose in air range from 16 to 178 nGy/h (with a mean of 42 nGy/h). Dust loading was found to range from 1.3 to 3.7 mg/m(3). Although the activity concentration of the radionuclides and the calculated annual absorbed dose is below the world's average, the dust level at the mines was relatively high. The results obtained show that the artisanal miners are exposed to various levels of radionuclides and dust and necessary precautions need to be taken.

Multielemental analysis of Migori (Southwest, Kenya) artisanal gold mine ores and sediments by EDX-ray fluorescence technique: implications of occupational exposure and environmental impact.

The results of heavy element profiling of the gold ores and sediments associated with the artisanal gold mining activities of the Migori gold belt of Southwestern Nyanza, Kenya, were reported in this paper. The analysis was made to assess the occupational exposure of the miners as well as to investigate the environmental impact of toxic heavy metals. Gold ores and sediments from the artisanal gold processing were sampled in four artisanal gold mining areas: Osiri A, Osiri B, Mikei and Macalder (Makalda) and analyzed for heavy elemental content using (109)Cd radioisotope excited EDXRF spectrometry technique. Analysis consisted of direct irradiating of sample pellets. The concentrations of major elements detected were: titanium (711.41-10,766.67 mg/kg); cobalt (82.65-1,010.00 mg/kg); zinc (29.90-63,210 mg/kg); arsenic (29.30-8,246.59 mg/kg); gold (14.07-73.48 mg/kg); lead (16.31-14,999.40 mg/kg) and mercury (16.10-149.93 mg/kg). The average concentration of the heavy toxic metals i.e. arsenic, lead, titanium and zinc were found to be above 50 mg/Kg as recommended by World Health Organization.