Inductively-coupled Atomic Emission Spectroscopy Research Articles

Using ICP and micro-PIXE to investigate possible differences in the mineral composition of genetically modified versus wild-type sorghum grain

In the present study, possible differences in the mineral composition of transgenic versus non-transgenic sorghum grains were investigated using inductively coupled atomic emission spectroscopy (ICP-AES); and, in-tissue elemental mapping by micro Proton-Induced X-ray Emission (micro-PIXE) analysis. ICP AES was used to analyse the bulk mineral content of the wholegrain flour derived from each genotype; whilst micro-PIXE was used to interrogate localised differences in mineral composition specific to certain areas of the grain, such as the bran layer and the central endosperm tissue. According to the results obtained, no significant difference in the average Fe, Zn or Ca content was found to differentiate the transgenic from the wild-type grain using ICP-AES. However, using micro-PIXE, a significant reduction in zinc could be detected in the bran layer of the transgenic grains relative to wild-type. Although it is difficult to draw firm conclusions, as a result of the small sample size used in this study, micro-PIXE has nonetheless proven itself as a useful technique for highlighting the possibility that there may be reduced levels of zinc accumulation in the bran layer of the transgenic grains. Given that the genetic modification targets proteins that are highly concentrated in certain parts of the bran tissue, it seems plausible that the reduced levels of zinc may be an unintended consequence of the silencing of kafirin proteins. Although no immediate health or nutritional concerns emerge from this preliminary finding, it is noted that zinc plays an important biological role within this part of the grain as a structural stabiliser and antioxidant factor. Further study is therefore needed to assess more definitively the extent of the apparent localised reduction in zinc in the transgenic grains and how this may affect other important grain quality characteristics.

The application of portable XRF and benchtop SEM-EDS to Cu-Pd exploration in the Coldwell Alkaline Complex, Ontario, Canada

Mineral exploration is increasingly taking advantage of real time techniques that dramatically reduce the costs and time taken to obtain results compared to traditional analytical methods. Portable X-ray fluorescence (pXRF) is now a well-established technique that is used to acquire lithogeochemical data. To date, however, benchtop scanning electron microscopes, equipped with energy dispersive systems (bSEM-EDS) have received little attention as a possible mineral exploration tool. This study examines the utility of combining pXRF and bSEM-EDS to characterize the igneous stratigraphy and its relationship to Cu-Pd mineralization in a drill hole at the Four Dams occurrence, located within the Eastern Gabbro assemblage of the Coldwell Alkaline Complex, Canada. The first part of this study compares field portable and laboratory techniques. Seventy-two powdered samples analysed by pXRF are compared with traditional major elements analysed by inductively coupled atomic emission spectroscopy (ICP-AES) and trace elements by inductively coupled plasma spectrometry (ICP-MS), and the compositions of 128 olivine, clinopyroxene and plagioclase grains analysed by bSEM-EDS are compared with traditional electron microprobe data. Our results show that each portable technique yields results similar to their lab-based counterparts within the analytical capabilities and precisions of the respective instruments. The second part presents a case study for the application of pXRF and bSEM-EDS to resolve questions related to igneous stratigraphy as an aid to mineral exploration in a complicated geological setting. A major problem for Cu-Pd exploration in the Coldwell Complex of NW Ontario is that the oxide-rich units that host Cu-Pd mineralization in the Marathon Series are petrographically similar to the barren oxide-rich units in the Layered Series. However, the mineralized units are geochemically distinctive. Our results show that the mineralized Marathon Series can be distinguished from the barren Layered Series, including oxide-rich units of both, by combinations of P 2 O 5 , Ba, Zr and V/Ti values, determined by pXRF, combined with plagioclase, olivine or clinopyroxene compositions measured by bSEM-EDS. The combination of pXRF and bSEM-EDS thus shows considerable promise as an exploration technique. Supplementary material: Comparisons of pXRF analyses with ICP-AES, ICP-MS and IR analysis are available at http://doi.org/10.6084/m9.figshare.c.3291518

Submicron spheres of amorphous calcium phosphate forming in a stirred SBF solution at 55 °C

X-ray-amorphous calcium phosphate (ACP) spheres were synthesized in a simulated/synthetic body fluid (SBF) solution heated to 55 to 70°C under constant stirring at 850rpm. The specific SBF solution (Lac–SBF) was buffered by using Na-l-lactate and lactic acid, and did not contain any Tris or Hepes. The Lac–SBF solution of this study flawlessly matched the concentrations of the inorganic electrolyte ions of the human blood plasma. The monodisperse ACP spheres synthesized at 55°C were 245nm in diameter when the Lac–SBF solution contained 67mg/L gelatin. Samples were characterized by powder X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and inductively-coupled atomic emission spectroscopy.

Silver migration from nanosilver and a commercially available zeolite filler polyethylene composites to food simulants

Polyethylene composites containing AgionTM commercial silver ion filler at three different percentage fill rates (0.5, 1.0 and 2% w/w) and polyethylene composites containing laboratory produced silver nanoparticles (Agnps) at two different percentage fill rates (0.1 and 0.5% w/w) underwent migration tests according to Commission Regulation (EU) No. 10/2011. Migrated silver in the two simulants (acidified water with 3% acetic acid and distilled water) was quantified using two techniques: inductively coupled atomic emission spectroscopy (ICPAES) and Hach Lange spectroscopy. The former had higher sensitivity with mean silver migration from Agion composites (n = 12) ranging from < 0.001 to 1.50 × 10−2 mg l–1. Mean silver migration from Agnps composites ranged from 4.65 × 10−2 to 0.38 mg l–1 and 8.92 × 10−2 and 5.15 × 10−2 mg l–1 for Hach Lange spectrophotometry and ICPAES, respectively. Both percentage fill rate in the composite and the simulant type, as factors, were found to be significant in both silver migration from Agion (p < 0.0001 and < 0.01, respectively) and Agnps (p < 0.05 and < 0.01, respectively). Transmission electron microscopy (TEM) imagery showed differences in size distributions and morphology of particles (shape and degree of agglomeration) before and after migration. PE composites containing 0.5% Agion, simulating contact with non-acidic foods, was the only scenario that did not exceed the permitted migration level of non-authorised substances given in EU 10/2011. This study illustrates the need for careful engineering of the composite filler system to conform to limits with cognisance of food pH and percentage fill rate.

Metal-ion mediated separation of propylene from propane using PPO membranes

Tests with mixture of gases were carried out at room temperature (30±2°C) to determine selectivities and permeabilities of propylene and propane. The ideal selectivities of the membranes towards the olefin were also evaluated. Metal-incorporated poly (2,6-dimethyl-1,4-phenylene-oxide), (PPO) membrane was used for facilitating transport of the olefin through the membranes. The metals incorporated were Silver (Ag(I)), Palladium (Pd(II)), Ruthenium (Ru(III)) and Iridium (Ir(III)). PPO showed high ideal selectivities with respect to propylene. Among the metal-incorporated PPO membranes, significantly improved flux and selectivity was obtained especially for Ru(III) and Pd(II). Pd–PPO membranes exhibited two-fold improvement in propylene permeance with improved selectivity from 3.44 to 5.33. The membranes were characterised by Fourier Transform Infra Red spectroscopy (FTIR), Inductively Coupled Atomic Emission Spectroscopy (ICP-AES), Wide Angle X-ray-Diffraction (WAXD) and density measurements to understand the structural characteristics of the membrane responsible for the observed behaviour. From IR results the metals particularly Ru, Pd, Ag, Ir were found to interact with the polymer. The improved selectivity values of the metal incorporated polymers have been explained by a decrease in the effective distance ( d eff) between the adjacent intersegmental chains due to formation of metal–ion complex with the polymer matrix and hence a decrease in the free volume of the polymer upon metal incorporation. However, the significant improvements in the propylene permeabilities have been realised mainly due to the selective transport of propylene molecules mediated by the incorporation of selected metal ions.

Defect apatite series in synthetic and natural calcium phosphates: The concept of psuedoapatites

X-ray-amorphous calcium phosphate (ACP) spheres were synthesized in a simulated/synthetic body fluid (SBF) solution heated to 55 to 70 °C under constant stirring at 850 rpm. The specific SBF solution (Lac–SBF) was buffered by using Na-l-lactate and lactic acid, and did not contain any Tris or Hepes. The Lac–SBF solution of this study flawlessly matched the concentrations of the inorganic electrolyte ions of the human blood plasma. The monodisperse ACP spheres synthesized at 55 °C were 245 nm in diameter when the Lac–SBF solution contained 67 mg/L gelatin. Samples were characterized by powder X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and inductively-coupled atomic emission spectroscopy.