Direct Current Plasma-atomic Emission Spectrometry Research Articles

Phase Properties of Carbon-Supported Gold−Platinum Nanoparticles with Different Bimetallic Compositions

The ability to control the composition and phase properties of bimetallic nanoparticles is critical in exploring catalytic properties. In this paper we present results from a study aimed at determining those properties for carbon-supported gold−platinum (AuPt) catalysts with different bimetallic compositions. The bimetallic nanoparticle catalysts are prepared by a two-phase synthesis protocol employing organic monolayer encapsulation on bimetallic AuPt cores (∼2 nm). The size-controlled nanoparticles are assembled on carbon black support materials with controllable dispersion and metal loading and are further treated by calcination under controlled temperature and atmosphere. The core composition of the bimetallic nanoparticles is determined by direct current plasma-atomic emission spectroscopy. Structural characterization is carried out by X-ray diffraction. The bimetallic nanoparticles were shown to display alloy properties, which is in sharp contrast to the bimetallic miscibility gap known for the bulk...

Public health evaluation of cadmium concentrations in liver and kidney of moose ( Alces alces) from four areas of Alaska

Liver and/or kidney samples were collected from 139 hunter-killed moose from four areas of Alaska during 1986. The concentration of cadmium in organ tissue was determined by direct-current plasma atomic emission spectrometry. All results are reported as μg/g wet weight. Concentrations of cadmium in liver ranged from 0.06 μg/g to 9.0 μg/g; in the kidney cortex they ranged from 0.10 μg/g to 65.7 μg/g. Cadmium levels were significantly associated with location and age. The highest geometric mean liver (2.11 μg/g) and kidney cortex (20.2 μg/g) cadmium concentrations were detected in moose harvested near Galena, Alaska. Limited dietary information from Alaska and Canada indicates that the intake of moose liver or kidney does not exceed, in most individuals, the World Health Organization recommendations for weekly cadmium consumption of 400 μg to 500 μg. Additionally, human biomonitoring data from Canada and Alaska indicate exposure to cadmium is low except for individuals who smoke cigarettes. Given the nutritional and cultural value of subsistence foods, the Alaska Division of Public Health continues to support the consumption of moose liver and kidney as part of a well-balanced diet. Human biomonitoring studies are needed in Alaska to determine actual cadmium exposure in populations with a lifelong history of moose liver and kidney consumption.

Platinum-Catalyzed Synthesis of Water-Soluble Gold−Platinum Nanoparticles

The ability to control composition and size in the synthesis of bimetallic nanoparticles is important for the exploitation of the bimetallic catalytic properties. This paper reports findings of an investigation of a new approach to the synthesis of gold-platinum (AuPt) bimetallic nanoparticles in aqueous solution via one-phase reduction of AuCl(4-) and PtCl(4)(2-) using a combination of reducing and capping agents. Hydrogen served as a reducing agent for the reduction of Pt(II), whereas acrylate was used as a reducing agent for the reduction of Au(III). The latter reaction was found to be catalyzed by the formation of Pt as a result of the reduction of Pt(II). Acrylate also functioned as capping agent on the resulting nanocrystals. By controlling the feed ratios of AuCl(4-) and PtCl(4)(2-) and the relative concentrations of acrylate, an effective route for the preparation of AuPt nanoparticles with bimetallic compositions ranging from approximately 4 to 90% Au and particle sizes ranging from 2 to 8 nm has been demonstrated. The composition, size, and shell properties were characterized using transmission electron microscopy, direct current plasma-atomic emission spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. Implications of the results to the exploration of bifunctional catalysts are also briefly discussed.

Preparation, Characterization, and Activity of Silica Supported Metallocene Catalysts

Silica supported metallocene catalysts were prepared for ethylene polymerization by immobilizing bis(cyclopentadienyl)zirconium dichloride (Cp2ZrCl2) onto both calcined silica, and silica treated with γ-aminopropyltrimethoxysilane or γ-mercaptopropyltrimethoxy-silane. Bis(cyclopentadienyl)zirconium chloride hydride (Cp2ZrClH) was also immobilized onto both calcined silica and vinyltrimethoxysilane treated silica. The catalysts were characterized by using direct current plasma atomic emission spectroscopy (DCP-AES), diffuse reflectance infrared spectroscopy (DRIFT), and X-ray photoelecton spectroscopy (XPS). It was found that both Cp2ZrCl2 and Cp2ZrClH were adsorbed on both calcined silica and silane treated silica, respectively. When γ-aminopropyltrimethoxysilane (APTMS) was used as the spacer molecule, some of the amine became protonated upon adsorption of Cp2ZrCl2. Initial catalytic tests showed that all of the complexes were catalytically active (methylaluminoxane as a cocatalyst), with the Cp2ZrClH supported complexes giving the highest activities, but still lower than the homogeneous catalyst, Cp2ZrCl2. The supported complexes produced polymer with higher molecular weight than the homogeneous catalyst. These observations, together with presented spectral evidence, support the view that the catalyst remained adsorbed in the presence of MAO.

Pharmacokinetics of sodium borocaptate: a critical assessment of dosing paradigms for boron neutron capture therapy.

The pharmacokinetics of sodium borocaptate (BSH), a drug that has been used clinically for boron neutron capture therapy (BNCT) of malignant brain tumors, have been characterized by measuring boron concentrations by direct current plasma-atomic emission spectroscopy (DCP-AES) in a group of 23 patients with high-grade gliomas. The disposition of BSH following intravenous (i.v.) infusion, which was determined by measuring plasma boron concentrations by DCP-AES, was consistent with a three-compartment open model with zero-order input and first-order elimination from the central compartment. Boron disposition was linear over the dose range of 26.5-88.2 mg BSH/kg body weight (b.w.), corresponding to 15-50 mg boron/kg b.w. Mean total body boron plasma clearance was 14.4 +/- 3.5 ml/min and the harmonic mean half-lives (range) were 0.6 (0.3-3.7), 6.5 (4.8-10.1) and 77.8 (49.6-172.0) h for the alpha, beta, and gamma disposition phases, respectively. Using an empirically determined plasma: blood boron concentration ratio of 1.3 +/- 0.2, the calculated total body boron blood clearance was 18.5 +/- 4.5 ml/min. In order to develop a model for selecting the optimum dosing paradigm, a pharmacokinetic correlation was established between the boron content of normal brain, solid tumor, and infiltrating tumor to the shallow tissue pharmacokinetic compartment (C2). Based on our model, it was concluded that although multiple i.v. infusions of BSH might increase absolute tumor boron concentrations, they will not improve the tumor: plasma boron concentration ratios over those attainable by a single i.v. infusion. The results from our study are confirmatory of those previously reported by others when blood sampling has been carried out for a sufficient period of time to adequately characterize the pharmacokinetics.

Characterizations of Core-Shell Nanoparticle Catalysts for Methanol Electrooxidation

ABSTRACTThis paper describes the results of an investigation of the structure and composition of core-shell gold and alloy nanoparticles as catalytically active nanomaterials for potential fuel cell catalysis. Centered on the electrocatalytic methanol oxidation, we show three sets of results based on electrochemical, surface, and composition characterizations. First, electrochemical studies have revealed that the nanostructured catalysts are active towards the electrooxidation of methanol and carbon monoxide. Second, X-ray photoelectron spectroscopy (XPS) data have shown that the organic encapsulating shells can be effectively removed electrochemically or thermally, which involves the formation of oxides on the nanocrystals. Thirdly, direct current plasma - atomic emission spectrometry (DCP-AES) has revealed insights for the correlation of the composition of alloy nanoparticles with the catalytic activities. Implications of these results to the design of nanostructured catalysts will also be discussed.

Systematic Variation in Galena Solid-Solution Compositions atSanta Eulalia, Chihuahua, Mexico

Argentiferous galena is the main silver-bearing phase at both the East and West camps of the Santa Eulalia district, Chihuahua, Mexico. The silver occurs as a coupled substitution of Ag and Sb for Pb in PbS with compositions ranging from 0.04 to 5.9 atomic percent (at. %) Ag and 0.10 to 7.2 at. percent Sb. Correlation analysis between Ag and Sb resulted in r values of 0.97 and 0.99 (significant at the 98% confidence level) for direct-current plasma-atomic emission spectroscopy (DCP-AES) and microprobe analysis of galena, respectively. Discrete and crystallographically oriented inclusions of diaphorite (usually 1 μ m or smaller) were common in high silver-antimony galenas and rare in low silver types (when present, tend to be larger). These inclusions were most abundant in the core zones of the crystals and rare on the edges. Spatial and temporal variations in Ag-Sb concentrations and ratios in galena were found mainly in the West camp of the district. High silver galenas (maximum 5.9 at. %) are confined to skarn zones or deep manto and chimney areas. The Ag/Sb ratio increases in galena from depth (0.88) to the surface (1.04) and from south (0.76) to north (0.94), following zonation and flow patterns established in previous investigations. Differences in Ag-Sb substitution in galena are also seen in different mineralization types: breccia zones, deep mantos, and chimneys contain more Ag-Sb (3.5 at. % avg) and have lower Ag/Sb ratios (avg ratio = 0.88) than the upper mantos, silicate and calc-silicate orebodies, which have lower Ag-Sb concentrations (2.2 avg at. %) but higher ratios (avg ratio = 1.00). Silver and antimony substitution also correlates with sulfur isotope variation in the district. Within individual orebodies, the δ 34S value increases with decreasing silver and antimony concentrations in galena. The solid-solution compositional variations in galena coupled with sulfur isotope values are a useful tool for inferring fluid paths and appear to reflect fluid evolution. At Santa Eulalia, silver is disseminated to various degrees throughout the orebodies and galena solid-solution concentrations appear to be controlled by subtle physical and/or chemical gradients. This contrasts with volcanic-epithermal systems in which significant physiochemical perturbations (large thermal and pressure gradients, boiling, etc.) lead to dumping of precious metals and semimetals as sulfosalts in bonanza zones. Relatively low concentrations of other potential ore-forming elements, namely copper and bismuth, also precluded the formation of a complex suite of silver sulfosalts and antimonian-argentiferous galena precipitated instead. Sulfosalts at Santa Eulalia are localized to upper mineralized zones as breccia void fillings, indicative of limited zones of boiling.

Boron Neutron Capture Therapy of Brain Tumors: Biodistribution, Pharmacokinetics, and Radiation Dosimetry of Sodium Borocaptate in Patients with Gliomas

The purpose of this study was to obtain tumor and normal brain tissue biodistribution data and pharmacokinetic profiles for sodium borocaptate (Na2B12H11SH) (BSH), a drug that has been used clinically in Europe and Japan for boron neutron capture therapy of brain tumors. The study was performed with a group of 25 patients who had preoperative diagnoses of either glioblastoma multiforme (GBM) or anaplastic astrocytoma (AA) and were candidates for debulking surgery. Nineteen of these patients were subsequently shown to have histopathologically confirmed diagnoses of GBM or AA, and they constituted the study population. BSH (non-10B-enriched) was infused intravenously, in a 1-hour period, at doses of 15, 25, and 50 mg boron/kg body weight (corresponding to 26.5, 44.1, and 88.2 mg BSH/kg body weight, respectively) to groups of 3, 3, and 13 patients, respectively. Multiple samples of tumor tissue, brain tissue around the tumors, and normal brain tissue were obtained at either 3 to 7 or 13 to 15 hours after infusion. Blood samples for pharmacokinetic studies were obtained at times up to 120 hours after termination of the infusion. Sixteen of the patients underwent surgery at the Beijing Neurosurgical Institute and three at The Ohio State University, where all tissue samples were subsequently analyzed for boron content by direct current plasma-atomic emission spectroscopy. Blood boron values peaked at the end of the infusion and then decreased triexponentially during the 120-hour sampling period. At 6 hours after termination of the infusion, these values had decreased to 20.8, 29.1, and 62.6 microg/ml for boron doses of 15, 25, and 50 mg/kg body weight, respectively. For a boron dose of 50 mg/kg body weight, the maximum (mean +/- standard deviation) solid tumor boron values at 3 to 7 hours after infusion were 17.1+/-5.8 and 17.3+/-10.1 microg/g for GBMs and AAs, respectively, and the mean tumor value averaged across all samples was 11.9 microg/g for both GBMs and AAs. In contrast, the mean normal brain tissue values, averaged across all samples, were 4.6+/-5.1 and 5.5+/-3.9 microg/g and the tumor/normal brain tissue ratios were3.8 and 3.2 for patients with GBMs and AAs, respectively. The large standard deviations indicated significant heterogeneity in uptake in both tumor and normal brain tissue. Regions histopathologically classified either as a mixture of tumor and normal brain tissue or as infiltrating tumor exhibited slightly lower boron concentrations than those designated as solid tumor. After a dose of 50 mg/kg body weight, boron concentrations in blood decreased from 104 microg/ml at 2 hours to 63 microg/ml at 6 hours and concentrations in skin and muscle were 43.1 and 39.2 microg/g, respectively, during the 3- to 7-hour sampling period. When tumor, blood, and normal tissue boron concentrations were taken into account, the most favorable tumor uptake data were obtained with a boron dose of 25 mg/kg body weight, 3 to 7 hours after termination of the infusion. Although blood boron levels were high, normal brain tissue boron levels were almost always lower than tumor levels. However, tumor boron concentrations were less than those necessary for boron neutron capture therapy, and there was significant intratumoral and interpatient variability in the uptake of BSH, which would make estimation of the radiation dose delivered to the tumor very difficult. It is unlikely that intravenous administration of a single dose of BSH would result in therapeutically useful levels of boron. However, combining BSH with boronophenylalanine, the other compound that has been used clinically, and optimizing their delivery could increase tumor boron uptake and potentially improve the efficacy of boron neutron capture therapy.

Mechanisms of transport of p-borono-phenylalanine through the cell membrane in vitro.

The mechanisms of transport of p-(dihydroxyboryl)-phenylalanine (BPA) through the cell membrane were investigated in vitro, evaluating especially the systems responsible for the transport of neutral amino acids as potential carriers for BPA. Rat 9L gliosarcoma cells and Chinese hamster V79 cells were exposed to BPA under controlled conditions and in a defined medium that was free of amino acids. The time course of (10)B (delivered by BPA) uptake and efflux was measured under different conditions. To analyze the intracellular boron content, direct-current plasma atomic emission spectroscopy (DCP-AES) was used after separating the cells from extracellular boron in the cell medium using an oil filtration technique. The dependence of factors such as cell type, temperature, composition and concentration of amino acids and specific substrates for amino acid transport systems in the culture medium or in intracellular compartments on BPA uptake and efflux were studied. The results of this study support the hypothesis that BPA is transported by the L system and that transport can be further stimulated by amino acids preaccumulated in the cell by either the L or A amino acid transport system.

Atomic emission spectrometric determination of ephedrine, cinchonine, chlorpheniramine, atropine and diphenhydramine based on formation of ion associates with ammonium reineckate

Ion–associate complexes of ephedrine HCl (I), cinchonine HCl (II), chlorpheniramine maleate (III), atropine sulphate (IV) and diphenhydramine HCl (V) with ammonium reineckate were precipitated and their solubilities were studied as a function of pH, ionic strength and temperature. Saturated solutions of each ion–associate under the optimum precipitation conditions were prepared and the Cr ion content in the supernatant was determined. The solubility products were thus elucidated at different temperatures. A new accurate and precise method using direct current plasma–atomic emission spectrometry for the determination of the investigated drugs in pure solutions and in pharmaceutical preparations is described. The drugs can determined by the present method in the ranges 1.6–52,2.64–85.8,3.12–101.4,5.52–180.4 and 2.72–75.85 μg/ml solutions of I, II, III, IV and V, respectively.

Enhanced delivery of boronophenylalanine for neutron capture therapy of brain tumors using the bradykinin analog Cereport (Receptor-Mediated Permeabilizer-7).

Using the well-characterized F98 rat glioma model, the purpose of the present study was to determine whether the delivery of boronophenylalanine (BPA) could be enhanced by prior administration of the bradykinin analog Cereport (Alkermes, Inc., Cambridge, MA) (previously known as Receptor-Mediated Permeabilizer-7), which produces a transient, pharmacologically mediated opening of the blood-brain barrier. Two series of experiments were performed in F98 glioma-bearing rats that had received either intracarotid (i.c.) or intravenous infusions of Cereport (at doses ranging from 1.5 to 7.5 microg/kg of body weight), followed by i.c. (or intravenous) injection of BPA (300 mg/kg of body weight). Animals were killed 0.5, 2.5, or 4 hours later, samples of blood, skin, muscle, and eye were obtained, brains were removed, and tumors were excised for boron determination by direct current plasma-atomic emission spectroscopy. Averaged over all time points, i.c. infusion of Cereport significantly enhanced tumor boron uptake (P = 0.0001), compared with the excipient (saline) control values. Tumor boron values were equivalent at 0.5 (36.0 microg/g) and 2.5 hours (38.5 microg/g) after i.c. administration of Cereport and BPA and then decreased by 33% (to 25.7 microg/g) at 4 hours. These tumor boron uptake values were significantly different (alpha = 0.05), compared with values measured at the corresponding times after i.c. administration of BPA without Cereport (22.6, 21.8, and 15.3 microg/g, respectively). Although no time-related effects were observed, i.c. administration of Cereport followed by intravenous administration of BPA also significantly enhanced (alpha = 0.05) tumor boron uptake at 0.5, 2.5, and 4 hours (27.4, 30.3, and 28.0 microg/g, respectively), compared with values obtained without Cereport (11.3, 13.4, and 15.2 microg/g, respectively). Boron levels in normal brain tissue from tumor-bearing and non-tumor-bearing cerebral hemispheres and in blood were not significantly different from those measured in saline-treated control animals. This study established that i.c. infusion of Cereport significantly increased delivery of BPA to F98 rat gliomas, and this could enhance the efficacy of boron neutron capture therapy of this tumor.

Multivariate data analysis as a tool for evaluating emission intensity, background equivalent concentration and detection limit obtained for different plasma positions in direct current plasma-atomic emission spectrometry

Relative emission intensity, background emission concentration (BEC) and detection limit (DL) obtained for different analytes and different plasma positions are examples of multivariate data sets. The observations can be related to the emission distribution in the plasma for the different elements (the spatial profiles). Principal component analysis (PCA) as a tool for modelling, interpretation and visualisation of such data sets was applied (i) to elucidate the data structure caused by the profiles, (ii) to enhance structural information using replicate or similar data sets, (iii) to predict model results that are less prone to errors and random variations, and (iv) to compare data sets of different origin (e.g. directly observed results with those calculated from the profiles). The selection of a suitable optimisation element can be guided by visual procedures or rather simple calculations based on the PCA model.

Laboratory and analytical method performance of lead measurements in paint chips, soils, and dusts.

The National Lead Laboratory Accreditation Program (NLLAP) recognizes laboratories capable of analyzing lead in paints, soils, and dusts. NLLAP requires successful participation in the Environmental Lead Proficiency Analytical Testing (ELPAT) program. For paint chip analyses, laboratory-to-laboratory variability is about 10% relative standard deviation (RSD) for lead levels near 0.5%, the HUD definition of lead-based paint. For soil analyses, RSDs are about 9 to 10% near relevant federal soil standards and 16% near the lowest state bare soil standard that currently exists. For dust wipe analyses, RSDs range from 10 to 16% for lead levels near relevant HUD standards. Of participating laboratories, 92 to 93% consistently meet ELPAT performance limits. A variety of analytical methods gives similar results. No conclusive significant differences were found among most frequently used hotplate and microwave sample preparation techniques. In addition, several participating laboratories have successfully used ultrasonic extraction methods, a method suitable for use at abatement sites. The three most frequently used instrumental techniques, flame atomic absorption (FAA), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and graphite furnace atomic absorption show no statistically significant differences in ability to meet ELPAT performance limits. However, small statistically significant biases between these methods sometimes occur. The magnitude of biases is less than 5% of the corresponding laboratory mean near relevant federal standards except for lead levels near the lowest HUD lead wipe standard, where biases can be as high as 8%. Other instrumental methods that have been used successfully include ICP-mass spectroscopy, direct current plasma-atomic emission spectroscopy, dithizone spectrophotometry, and anodic stripping voltametry.

Laboratory and Analytical Method Performance of Lead Measurements in Paint Chips, Soils, and Dusts

The National Lead Laboratory Accreditation Program (NLLAP) recognizes laboratories capable of analyzing lead in paints, soils, and dusts. NLLAP requires successful participation in the Environmental Lead Proficiency Analytical Testing (ELPAT) program. For paint chip analyses, laboratory-to-laboratory variability is about 10% relative standard deviation (RSD) for lead levels near 0.5%, the HUD definition of lead-based paint. For soil analyses, RSDs are about 9 to 10% near relevant federal soil standards and 16% near the lowest state bare soil standard that currently exists. For dust wipe analyses, RSDs range from 10 to 16% for lead levels near relevant HUD standards. Of participating laboratories, 92 to 93% consistently meet ELPAT performance limits. A variety of analytical methods gives similar results. No conclusive significant differences were found among most frequently used hotplate and microwave sample preparation techniques. In addition, several participating laboratories have successfully used ultrasonic extraction methods, a method suitable for use at abatement sites. The three most frequently used instrumental techniques, flame atomic absorption (FAA), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and graphite furnace atomic absorption show no statistically significant differences in ability to meet ELPAT performance limits. However, small statistically significant biases between these methods sometimes occur. The magnitude of biases is less than 5% of the corresponding laboratory mean near relevant federal standards except for lead levels near the lowest HUD lead wipe standard, where biases can be as high as 8%. Other instrumental methods that have been used successfully include ICP-mass spectroscopy, direct current plasma-atomic emission spectroscopy, dithizone spectrophotometry, and anodic stripping voltametry.

US Food and Drug Administration survey of cadmium, lead and other elements in clams and oysters.

In Fiscal Years 1985/1986, the US Food and Drug Administration conducted a survey of cadmium, lead and other elements in fresh clams and oysters collected from US coastal areas in use for shellfish production. Shellfish were analysed for cadmium and lead by using a dry ash-anodic stripping voltammetric method. Other elements (aluminium, arsenic, beryllium, calcium, chromium, cobalt, copper, iron, magnesium, manganese, molybdenum, nickel, phosphorus, potassium, selenium, sodium, strontium, vanadium and zinc) were determined by using inductively coupled plasma-atomic emission spectrometry, direct current plasma-atomic emission spectrometry or hydride generation atomic absorption spectrometry. A total of 75 hardshell clam, 59 softshell clam, 104 Eastern oyster and 40 Pacific oyster samples were analysed for cadmium and lead. Average levels found were 0.09, 0.05, 0.51 and 1.1 mg/kg wet weight for cadmium and 0.24, 0.30, 0.11 and 0.06 mg/kg wet weight for lead in hardshell clams, softshell clams, Eastern oysters and Pacific oysters, respectively. The other 19 elements were determined in 10-104 samples of the four types of shellfish. These data provide baseline values for elements in clams and oysters harvested from US coastal waters.

Determination of equilibrium constants of alkaline earth metal ion chelates with Dowex A-1 chelating resin

A complexation chemistry model is applied to chelating ion-exchange systems and a method is presented for the determination of equilibrium constants for metal ion chelates with these resins. Protonation constants for the iminodiacetic based chelating resin Dowex A-1 were determined from potentiometric pH-data. Equilibrium constants were determined for 1:1 beryllium, magnesium, calcium, strontium and barium chelates with the resin in a wide pH range by measuring the concentrations of respective metal ions in the aqueous phase with direct current plasma atomic emission spectrometry (DCP-AES). A batch technique was used for the equilibrium experiments. At pH below 7 protonated 1:1 species were also found to be formed with the resin. From the obtained equilibrium constants, theoretical distribution coefficients were calculated as function of pH for respective metal ion resin system.

Sequential injection analysis system for the determination of hydride-forming elements by direct current plasma atomic emission spectrometry

A method for the determination of volatile hydride-forming elements with direct current plasma atomic emission spectrometry (DCP-AES) based on a modified version of the sequential injection analyser has been developed. The sequential injection (SI) hydride generator consists of two multi-port valves and a piston burette. The burette is also used as a dynamic reaction chamber the volume of which can be changed by the piston movement. This arrangement allows isobaric reaction. The burette also functions as a gas–liquid separator where the liquid reaction products are drained via a channel through the piston head. The hydride gases are pumped by the piston into the plasma through a thin quarts capillary, which is also used to position the direction of gas flow to the centre of the plasma. All functional parts in this system are computer controlled. The performance of the SI hydride generation DCP-AES system has been tested in the determination of arsenic, bismuth and germanium. The detection limits (3s) were 0.15, 0.08 and 0.03 µg l–1, respectively. The calibration graphs were linear (r >0.999) in the concentration ranges studied: 0–50 µg l–1 for arsenic and 0–10 µg l–1 for bismuth and germanium. The relative standard deviation for all three elements was less than 10% at a concentration level of 1 µg l–1 and ≈3% at the 10 µg l–1 level. The accuracy of the method was tested in the determination of arsenic in the National Institute of Standards and Technology (NIST) Standard Reference Materials, NIST SRM 1573 Tomato Leaves and NIST SRM 1575 Pine Needles.

Determination of Calcium, Magnesium and Phosphorus in Small Amounts of Rat Tissues by Direct Current Plasma-(DCP)-Atomic Emission Spectrometry

Abstract A procedure is described for simultaneous determination of Ca, Mg and P in small amounts (a few mg) of tissues by use of Direct Current Plasma-Atomic Emission Spectrometry. The samples were analyzed by using matrix matched standards. The necessity to use high-purity acids for decomposition of samples is demonstrated. The method was tested on four different reference samples. The accuracies for the elements were satisfactory (93–103%). The within-run and between-run precisions were 0.9–6.8 and 0.9–8.6%, respectively. The method may be used for determination of other elements.

DCP-Atomic Emission Spectrometric Study of REE in Phosphates

Abstract A method has been developed for the application of direct current plasma atomic emission spectrometry (DCP-AES) to the determination of rare earth elements (REE) in samples of phosphates collected from the Abu Tartur area, Western Desert, Egypt. Complete dissolution of the samples was achieved using an HF/HNO3/HClO4 digestion procedure. Careful study of line overlap interference originating from REE as well as from minor and major constituents of the samples enabled the selection of the RE spectral lines appropriate for the analysis. Optimization of the DCP was necessary with respect to gas pressure and observation zone. The matrix effect due to the presence of Ca and Al was studied. The total content of REE directly determined in the samples ranged between 1.054 and 1.648 mg/gm. The results reveal the applicability of the DCP-AES for the direct determination of 11 REE in phosphate samples. ∗ NRC Phys. Dept. Spectroscopy lab. Cairo Egypt. + Physics Department, Faculty of Science, ALAZHAR Universi...

Silicon analysis in biological specimens by direct current plasma-atomic emission spectroscopy.

A method for the determination of total elemental silicon concentrations in biological fluids by direct current plasma-atomic emission spectrometry (DCP-AES) is presented. The method is linear up to 30 micrograms/mL in blood, serum, plasma, and urine, with a detection limit of 0.2 microgram/mL. Population ranges of silicon concentration in blood, plasma, serum, and urine were found to be less than 0.3 to 33 micrograms/mL, less than 0.4 to 39 micrograms/mL, less than 0.2 to 68 micrograms/mL, and less than 0.3 to 180 micrograms/mL, respectively. Over 50% of all measured concentrations were less than 0.5 microgram/mL for blood, plasma, and serum. Estimates of "normal" population ranges are reported, and potential applicability of this procedure to silicone-related maladies is discussed.