Trace Aluminum Research Articles

Determination of trace aluminum in foods by stripping voltammetry

The study of electrochemical behavior of aluminum–cupferron complex indicated that aluminum and cupferron formed complex in 0.4 mol/L (NH 4) 2SO 4 solution. Accumulation potential of −0.95 V (vs. SCE) was applied, while the solution was stirred for 60 s. The response curve was recorded by scanning the potential to the negative direction and the peak current of −1.18 V (vs. SCE) was recorded. This complex absorbed in hanging mercury drop electrode (HMDE) and create a sensitive peak current. The peak current and concentration of aluminum accorded with linear relationship in the range of 4.0 × 10 −8–2.0 × 10 −9 g/mL. The relative standard deviation (at 10 μg/L) is 3.0% and the detection limit is 8 × 10 −10 g/mL. The interference of some common ions was studied. This method has been used to determine trace aluminum in foods and water.

Determination of trace aluminum by fluorescence quenching method based on catalysis of potassium chlorate oxidizing alizarin red

A new method for the determination of trace aluminum has been proposed. It is based on the fact that alizarin red can emit strong and stable fluorescence at 80 °C for 30 min and Al 3+ can effectively catalyze potassium chlorate oxidizing alizarin red to form non-fluorescence complex which cause the fluorescence quenching. The linear dynamic range of this method is 0.040–4.00 ng l −1 with a detection limit of 5.3 pg l −1. The regression equation can be expressed as Δ I f = 8.731 + 21.73 c A l 3 + (ng l −1), with the correlation coefficient r = 0.9992 ( n = 6). This sensitive, rapid and accurate method has been applied to the determination of trace aluminum(III) in human hair and tea samples successfully. What is more, the mechanism of catalyzing potassium chlorate oxidizing alizarin red by the fluorescence quenching method is also discussed.

Application of Cu-polyimide flex circuit and Al-on-glass pitch adapter for the ATLAS SCT barrel hybrid

We applied the surface build-up Cu-polyimide flex-circuit technology with laser vias to the ATLAS SCT barrel hybrid to be made in one piece from the connector to the electronics sections including cables. The hybrids, reinforced with carbon–carbon substrates, provide mechanical strength, thermal conductivity, low-radiation length, and stability in application-specific integrated circuit (ASIC) operation. By following the design rules, we experienced little trouble in breaking the traces. The pitch adapter between the sensor and the ASICs was made of aluminum traces on glass substrate. We identified that the generation of whiskers around the wire-bonding feet was correlated with the hardness of metallized aluminum. The appropriate hardness has been achieved by keeping the temperature of the glasses as low as room temperature during the metallization. The argon plasma cleaning procedure cleaned the contamination on the gold pads of the hybrids for successful wire bonding, although it was unsuccessful in the aluminum of the pitch adapters.

Bacterial-Metal Interactions: The Potential Role of Aluminum and Other Trace Elements in the Etiology of Chrohn’s Disease

Despite the recent burst of excitement about the genomics of Crohn’s disease, the critical importance of environmental factors in this condition has been recognized ever since the disease was described. The chief suspects for this role have always been microorganisms and dietary constituents. Many candidate microorganisms have been proposed, evaluated and discarded over the decades, but the most persistent theories have revolved around mycobacterial infection. Among potential dietary agents, however, none has yet emerged as a favorite. An offending dietary constituent, of course, need not be conventional foodstuff; additives, preservatives, and even microparticle contaminants are plausible alternatives. With this in mind, we have arrived at an etiologic hypothesis for Crohn’s disease based on our study of a fatal outbreak of granulomatous enteritis in a group of horses sharing a common environment. The horses suffered from a disorder with many histologic similarities to human Crohn’s disease. In the evaluation of the cluster, an unexpected finding was the presence of excess aluminum in affected tissues. Microprobe elemental analysis demonstrated that aluminum was concentrated within microorganisms in the intestinal wall. Based on these observations, we propose a novel approach to etiologic concepts of Crohn’s disease. Our hypothesis is that the capability of certain microbial organisms, in particular mycobacterial species, to take up certain trace elements from environmental and host sources, may alter the pathogenicity of these organisms and exacerbate the host’s responses to them. As we will outline, mycobacteria possess potent metal chelators that provide essential metallic elements, especially iron, required for bacterial growth and virulence. We propose that in addition to iron, other metals, particularly aluminum, may use these same metal chelating systems to gain access to the organisms and this may alter their pathogenicity and ability to induce an exuberant granulomatous response. It is well established that the virulence and even survival of many bacterial organisms during infection depends on the ability of the pathogenic microbe to compete for essential nutrients, especially iron. However, in vertebrates iron remains sequestered within a number of high molecular weight binding proteins, such as transferrin, lactoferrin and ferritin. In what is essentially an iron-poor environment, microorganisms have evolved to produce ferric ion chelating agents, called siderophores, that are capable of solubilizing and transporting iron into the microbe. Siderophores contain some of the most efficient ironbinding ligands in nature and are capable of securing the metal from transferrin, ferritin, ferric hydroxide as well as from synthetic chelators such as EDTA. The affinity of siderophores for iron is remarkably strong with dissociation constants (Ks) in the range of 10 to 10.

Spectrofluorimetric determination of trace aluminum in diluted hemodialysis solutions

In this study, a spectrofluorimetric method has been developed for the determination of aluminum based on the formation of an aluminum complex with N, N′-disalicylidene-1,3-diamino-2-hydroxypropane (DSAHP). The most suitable pH, solvent medium, complex formation time, Schiff base concentration and temperature were determined. The excitation and emission wavelengths were 270 and 437 nm, respectively, in which the DSAHP–Al complex gave the maximum flurescence intensity at pH 3.0 and 6.0 in 50% dioxan–50% water medium. Under these conditions, calibration curves were obtained in three different linear limits, and was found that aluminum could be detected within the concentration limit of 0–10.0 μM and the lowest detection limit being 0.27 ng ml −1. The stochiometry of the DSAHP–Al complex was also determined spectrofluorimetrically under optimal conditions and the molar ratio of DSAHP–Al was calculated as 2:1. Using the developed method, aluminum was detected in hemodialysis solutions, and the results obtained were similar and comparable with those obtained using the method described in the British Pharmacopoeia within 95% confidence limits. This method can be used successfully for the routine determination of aluminum because it is quick, requires less amount of reactives, is sensitive, reliable and reproducible.

Preconcentration of trace aluminum from environmental water samples with 5'-chloro-5-dodecyl-2,4,2'-trihydroxyazobenzene impregnated macroporous resin.

5'-Chloro-5-dodecyl-2,4,2'-trihydroxyazobenzene (CDTA) impregnated XAD-4 resin (CDTA resin) was prepared, and applied to the preconcentration of trace aluminum from environmental water samples with satisfactory results. Aluminum was measured by flow-injection analysis (FIA) with fluorescence detection by using lumogallion after the preconcentration of aluminum with CDTA resin. Fe3+ and other coexisting substances had no interference on the determination of aluminum by the present method. Chemical speciation of trace aluminum in environmental water was carried out by using the CDTA resin after the separation of aluminum species with ionic exchangers without changing the pH. About 50% of water-soluble aluminum in Lake Biwa was found to be aluminum organic species (anion species).

Direct determination of trace aluminum with quercetin by reversed-phase high performance liquid chromatography

The determination of trace levels of aluminum by high performance liquid chromatography (HPLC) with spectrophotometric detection using quercetin, a bioactive substance as a pre-column reagent, is developed in this paper. The Al–quercetin chelate was separated on a reversed-phase ODS column with a mobile phase consisting of 70% water (pH 1.0 with perchloric acid) and 30% methanol, and detected at its maximum of 415nm. The response was linear over the 1.0×10−7 to 8.0×10−5M concentration range with a detection limit of 5.0×10−8M and a relative standard deviation of 1.0% at the 5×10−6M level. The analysis was free from common ions except iron, which could be successfully screened by 1,10-phenanthroline. This method has been employed to the determination of Al in environmental and biological samples. Moreover, direct speciation of labile monomeric Al, the toxic form of Al, in natural water by the present technique was explored. The coordination ratio of Al complex with quercetin was also elucidated by HPLC combined with molar ratio method. Only a 1:1 complex was formed. Because quercetin exists in body, a preliminary thinking of in vivo determination of Al is provided in this study.

Kinetic Spectrophotometric Determination of Trace Aluminum by Catalytic Activity of Al 3+ on the Oxidation of Methylene Blue by Hydrogen Peroxide

A novel kinetic spectrophotometry for the determination of trace aluminum is described based on the catalytic activity of Al3+ on the redox reaction between methylene blue (MB) and hydrogen peroxide in acetate buffer (pH 3.8). The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of the dye at the maximum absorption wavelength of 670 nm. The variables that affected the reaction rate were fully investigated, and the optimum conditions were established. Aluminum can be determined in the range of 0–80 ng mL−1 with a detection limit of 1.0 ng mL−1. The relative standard deviation for 10 replicate determinations of 40 ng mL−1 aluminum is 0.9%. The method was used to determine aluminum in tap water and biological samples and produced satisfactory results.

Improvement of resonant laser ablation mass spectrometry using high-repetition-rate and short-pulse tunable laser system

The mass spectrometry based on resonant laser ablation technique (RLA-MS), which combines laser ablation and resonance ionization spectroscopy simultaneously with a single laser, can be used as a simple analytical technique of trace elements with high sensitivity and elemental (isotopic) selectivity for solid samples. In this study, a high-repetition-rate and short-pulse tunable laser (Ti:Sapphire laser) system is applied to improve the performance of RLA-MS. The basic performance has been checked through experiments and theoretical calculations for trace aluminum (Al) detection. The results show that the present RLA-MS system has a detection limit concentration approximately 3 ppb/s for Al, which would be approximately 100 times better than that of the conventional relatively low-repetition-rate and long-pulse dye laser system. The effectiveness of applying a short-pulse laser to RLA-MS is also discussed from the viewpoint of shortening an expansion time of the ablated vapor, which might lead to an advantage of the system compactness.

Molecular and atomic ultra trace analysis by laser induced fluorescence with OPO system and ICCD camera

This paper presents a synthesis of some analytical potentialities of an equipment designed for both laser induced molecular and atomic fluorescence in the field of ultra-trace analysis (ng l −1). Excitation of fluorescence was performed with a pulsed Nd:Yag laser coupled to an optical parametric oscillator (OPO). Fluorescence spectra were recorded with a spectrograph and an intensified charge-coupled device (ICCD). The high energy and the tunability of the excitation combined with the sensitivity of the ICCD and the time-resolution provide better limit of detection (LOD) and selectivity. By molecular fluorescence, some major organic contaminants in the environment were studied, i.e. polycyclic aromatic hydrocarbons (PAHs) (benzo[ a]pyrene and hydroxypyrene) and a pesticide (carbaryl). The LODs achieved by direct analysis were far below the restricted European values for tap water. Analysis was performed in water containing humic acids using time resolution to avoid the matrix fluorescence. By electro thermal atomisation-laser excited atomic fluorescence (ETA-LEAF), we detected traces of aluminium and lead in seawater. Some general considerations about the signal to noise ratio optimisation are reported. LODs reached the femtogram level.

Synthetic Silica Glass for Trace Aluminium Determination in Quartz by Electron Microprobe

Five synthetic silica glasses have been prepared for microprobe determination of trace aluminium in quartz. The glasses were synthesized from tetraethoxysilane (TEOS) into which between 0 and 1431 μg g‐1 aluminium had been doped. The aluminium concentrations of the glasses were independently determined by ICP‐AES analysis. X‐ray wavelength shift in the Al Kα peak was minimised relative to unknown quartz samples when these glasses were used for calibration. A set of these five glasses yielded a linear calibration line, and are available for trace aluminium analysis of quartz in routine microprobe systems.

Assessment of trace aluminium content in parenteral solutions by combined cloud point preconcentration—flow injection inductively coupled plasma optical emission spectrometry

A micelle-mediated phase separation without added chelating agents to preconcentrate trace levels of aluminium in parenteral solutions as a prior step to its determination by flow injection inductively coupled plasma optical emission spectrometry has been developed. The enrichment step is based on the cloud point extraction of aluminium with the non-ionic surfactant polyethyleneglycolmono- p-nonylphenylether (PONPE 7.5). The chemical variables affecting the sensitivity of the extractive-spectrometric procedure were studied in detail. After optimization, a preconcentration factor of 200 and a %E higher than 99.9 were achieved. The detection limit (DL) value of aluminium for the preconcentration of 50 ml of parenteral solution was 0.25 μg l −1. The calibration graph using the preconcentration system for aluminium was linear with a correlation coefficient of 0.9997 at levels near the DLs up to at least 200 μg l −1. The developed hyphenated assay, which thoroughly satisfies the typical requirements for pharmaceutical control processes, is appropriate to monitor the aluminium concentration in parenteral nutrition.

Epoxidation of Propylene with Dilute H2O2 over Titanium Silicalite Containing Trace Aluminum

Titanium silicalite (TS-1) was successfully synthesized by using TPABr as the template and silica sol as silicon source in a 100 l stainless steel autoclave. IR, XRD, UV--vis, elemental analysis, and 27Al and 31P MAS NMR were used to characterize the synthesized products. The results show that the synthesized material has an MFI structure with high crystallinity and large crystal size and two kinds of titanium species. Trace aluminum in silica sol is also incorporated into the zeolite framework. The synthesized TS-1 exhibits high activity in the epoxidation of propylene with dilute H2O2 with high selectivity to methyl mono-ethers and low selectivity to propylene oxide (PO). The low selectivity toward PO is due to the residual acidity onto TS-1. The selectivity of PO can reach up to 90% through adjusting the pH of the reaction mixture. Extra amounts of base decrease the H2O2 utilization and the H2O2 conversion. However, in over acid-treated TS-1 in which part removal of extra-framework titanium takes place, the utilization of H2O2 is quite different: for the low Si/Ti ratio of TS-1, the H2O2 utilization increases. But the utilization of H2O2 does not change for the high Si/Ti ratio TS-1. Thermal analysis shows that the as-synthesized TS-1 exhibits high activity and thermal stability in the calcined range 540-900 °C.

Synthetic silica glass for trace aluminum analysis in quartz by electron microprobe

Synthetic silica glass for trace aluminum analysis in quartz by electron microprobe

Electrothermal volatilization of aluminum as 1-phenyl-3-methyl-4-benzoylpyrazolone[5] chelate for gaseous sample introduction in ICP-AES

Based on gaseous compound introduction as 1-phenyl-3-methyl-4-benzoylpyrazolone[5](PMBP) chelate of aluminum by electrothermal vaporization in ICP-AES, a method for determination of trace aluminum was developed. Trace aluminum was vaporized at temperature of 1000 °C, and the vaporization behavior of aluminum chelate was detailedly investigated. Under the optimum conditions, the detection limit of aluminum was 0.6 ng ml −1, and the relative standard deviation for 0.1 μg ml −1 aluminum was 4.7% ( n=8). The proposed method was applied to the determination of trace aluminum in rice flour reference materials, and the results well agreed with the reference values.

Nuclei for heterogeneous formation of graphite spheroids in ductile cast iron

The crystal structure and composition of nuclei for graphite spheroids in a ductile cast iron containing small amounts of magnesium and traces of aluminium have been studied in a transmission electron microscope equipped with EDX and parallel electron energy loss spectrometer and in an electron microprobe analyser. The particles were identified as Al–Mg–Si nitrides, having a trigonal superlattice crystal structure derived from a hexagonal AlN type fundamental cell. The superlattice can be indexed according to a hexagonal Bravais lattice, with parameters a=0.544 nm and c=0.482 nm. The parameters of the fundamental cell are af=0.314 nm and cf=0.482 nm, deviating only 1–3% from the parameters of hexagonal AlN. Based on the compositional analysis, the chemical formula of the nitride particles is suggested to be AlMg2.5Si2.5N6.

Chemical diffusion of oxygen in tin dioxide

Tin(IV) oxide is widely used in the Taguchi sensor for the detection of redox-active gases. The performance of the sensor critically depends on oxygen transport parameters since perceptible values of the chemical diffusion coefficient of oxygen cause severe drift effects. The present work investigates the kinetics of oxygen exchange by two independent methods, an EPR relaxation technique and the well-known conductivity relaxation technique. The experiments were performed on nominally undoped single crystals which contained traces of iron and aluminum. In the temperature range from 700 to 1000°C the chemical diffusion coefficient is obtained as D δ =0.02 cm 2 s −1 exp(−0.9 eV/ kT). The results of the relaxation experiments were complicated by additional processes occurring on different time scales. A doping independence assumed, we conclude that the kinetics of drift processes are determined by the surface exchange reaction of oxygen on SnO 2 rather than by the chemical diffusion of oxygen.

DIRECT DETERMINATION OF ALUMINUM IN DRINKING AND NATURAL WATERS AS 8-HYDROXYQUINOLINE CHELATE BY RP-HPLC

Determination of trace aluminum in the form of 8-hydoxyl-quinoline chelate by reversed phase high performance liquid chromatography and spectrophotometric detection is described in this paper. The optimization of the experimental conditions including precolumn complexation, chromatographic separation, and detection wavelength is comprehensively investigated. The response is linear from 0.002 to 0.3 μg/mL with a detection limit of 0.002 μg/mL. The relative standard deviation is 3.6% at an Al concentration of 0.2 μg/mL. The reliability of the entirely optimized procedure is confirmed by the direct analyses performed on ten real drinking and natural water samples.

Determination of Aluminum and Beryllium by Diffuse Reflectance Spectrometry with the Use of Chromaticity Functions

Immobilized Eriochrome Cyanine R was used for the direct determination of trace aluminum and beryllium by diffuse reflectance spectrometry. Anion exchanger AV-17, silica gel Silochrom C-120, Chromaton N-Super, octadecyl silica gel, and cellulose were examined as supports. Optimal sorption conditions were found. The dependence of chromaticity functions (chromaticity coordinates, lightness, color saturation, yellowness, and whiteness) on different factors was studied. Advantages of the use of chromaticity functions rather then the diffuse reflectance coefficient were demonstrated. A method is developed for the separate determination of aluminum and beryllium using cellulose as the support; the method was used for the analysis of real samples and tested with standard samples. When solution samples of 50 and 100 mL were used, the determination limit was 0.004 μg/mL for aluminum and 0.0002 μg/mL for beryllium.

Spectrophotometric determination of trace aluminium content in parenteral solutions by combined cloud point preconcentration-flow injection analysis.

A cloud point preconcentration and flow injection (FI) analysis methodology for aluminium(III) determination has been developed. The analyte in the initial aqueous solution was complexed with Chrome Azurol S (CAS) in the presence of the cationic surfactant benzyldimethyltetradecylammonium chloride (BDTAC). The absorption spectroscopic characteristics of the ternary complex [Al(III)-CAS-BDTAC] were examined in detail. The preconcentration step was carried out by means of the non-ionic surfactant polyethylene glycol p-nonylphenyl ether (PONPE 7.5). The enriched analyte solution was injected into an FI system using an HPLC pump. The chemical variables affecting the analytical performance of the combined methodology were studied and optimised. The developed approach was successfully applied to the determination of trace amounts of aluminium in parenteral solutions without previous treatment. Under the optimum experimental conditions, 99.9% extraction was achieved for a preconcentration factor of 50. The limit of detection was 1.12 x 10(-7) mol(-1). The calibration plot was linear over at least two orders of magnitude of aluminium concentration. The developed coupled methodology, which thoroughly satisfies the typical requirements for pharmaceutical control processes, is appropriate for monitoring the aluminium concentration in parenteral nutrition.