Aluminum determination in biological fluids and dialysis concentrates via chelation with 8-hydroxyquinoline and solvent extraction/fluorimetry

Efficient and easily scaled-up biosorbent based on natural and chemically modified macauba (Acrocomia aculeata) to remove Al3+, Mn2+ and Fe3+ from surface water contaminated with iron mining tailings

The ruptures of tailings mine dams in the cities of Mariana and Brumadinho contaminated local Brazilian Rivers with toxic metals. Herein, we describe a scaled-up biosorbent based on natural macauba endocarp (NTE) and macauba endocarp chemically treated (TE) to remove Al³⁺, Mn²⁺ and Fe³⁺ from aqueous solutions. For the TE material: the variation of pH and temperature of water did not cause significant sorption interferences; the kinetics studies suggest a pseudo-second-order model; the adsorption isotherms revealed that the Langmuir equation was the best fit for Al³⁺ and Mn²⁺, while the Freundlich equation best described the Fe³⁺; and the maximum adsorption capacities were between 0.268 mg g^-1 and 1.379 mg g^-1. A scaled-up was carried out using an adsorption column to remove the metals from Rio Paraopeba River water samples and the results showed that both NTE and TE are potentially low cost biosorbents for removing Al³⁺, Mn²⁺ and Fe³⁺.

Selective Membrane Sensor for Aluminum Determination in Food Products, Real Samples and Standard Alloys

The study involves the fabrication of an aluminum liquid membrane sensor based on the association of aluminum ions with the cited reagent 2,9-dimethyl-4,11-diphenyl -1,5,8,12-tetraaza cyclote tradeca-1,4,8,11-tetraene [DDTCT]. The characteristics slope (58 mV), rapid and linear response for aluminum ion was displayed by the proposed sensor within the concentration range 2.5 × 10^-7-1.5 × 10^-1 M, the detection limit (1.6 × 10^-7) M, the selectivity behavior toward some metal cations, the response time 10 s), lifetime (150 days), the effect of pH on the suggested electrode potential and the requisite analytical validations were examined. The suitable pH range was (5.0-8.0 ), in this range the proposed electrode response is independent of pH. The suggested electrode was applied to detect the aluminum ions concentration in food products, real samples and standard alloys. The resulting data by the suggested electrode were statistically analyzed, and compared with the previously reported aluminum ion-selective electrodes in the literature.

Direct Rapid Determination of Trace Aluminum in Various Water Samples with Quercetin by Reverse Phase High-Performance Liquid Chromatography Based on Fabric Phase Sorptive Extraction Technique

The determination of trace levels of aluminum by high-performance liquid chromatography (HPLC) with UV detection using quercetin, a natural bioactive flavonol, as a metal complexation agent is presented in the current article. The developed method has been successfully applied to the direct determination of aluminum in water samples collected from various sources. A preconcentration technique is indispensable due to the presence of aluminum in environmental water at trace levels. Fabric phase sorptive extraction (FPSE), a relatively new but promising sample preparation technique, was applied to preconcentrate quercetin-Al(III) complex from water samples. Efficient extraction of the quercetin-Al(III) complex from aqueous samples has been accomplished by applying FPSE using a cellulose fabric substrate coated with sol-gel C18 hybrid nanocomposite sorbent. Baseline separation of Al-quercetin complex has been achieved on a reverse phase C18 column with the use of acetonitrile: 3% acetic acid (30:70; v/v) as the mobile phase at a flow rate of 1.0 mL/min. The new FPSE-HPLC-UV method can be used for the routine screening of Al ions in various water samples with high sensitivity, precision and reliability.

The simple design of a new recyclable magnetic carbon graphite adsorbent based on 2-amino-5-mercapto-1,3,4-thiadiazole for the fast extraction of two anti-depressant drugs

In this work, an efficient magnetic nanoadsorbent, cubic SnFe₂O₄/graphitic carbon nitride (g-C₃N₄) modified by 2-amino-5-mercapto-1,3,4-thiadiazole (AMT), was synthesized.

Butan-1-ol as an extractant solvent in dispersive liquid-liquid microextraction in the spectrophotometric determination of aluminium

Determining aluminium ions at μg L^-1 scale currently requires either costly analytical techniques such as inductively coupled plasma, and/or graphite furnace atomic absorption spectrometry. Dispersive liquid-liquid microextraction (DLLME) is designed to promote separation and preconcentration, thus making it possible to determine the analyte of interest without significant matrix influence. This study was aimed at the development of a spectrophotometric method to determine Al³⁺ after microextraction of its complex with quercetin. Butan-1-ol was used as a novel extractant solvent in the DLLME process. The parameters influencing complexation and microextraction, such as the amount of quercetin and volume of extractant were evaluated by univariate analysis. In optimised conditions were estimated for the proposed method: linear range from 7.5 to 165.0 μg L^-1, LOD of 2.0 μg L^-1, and LOQ of 7.0 μg L^-1. The accuracy was checked by applying the proposed method to water (NIST SRM-1643e) and rice flour (NIST SRM-1568c) certified reference materials and spike-and-recovery trials with distinct samples (mineral water, green tea, thermal spring water, contact lens disinfecting solution, saline concentrate for hemodialysis and urine).

Quantitative Determining of Ultra-Trace Aluminum Ion in Environmental Samples by Liquid Phase Microextraction Assisted Anodic Stripping Voltammetry

Direct detecting of trace amount Al(III) in aqueous solution by stripping voltammetry is often frustrated by its irreversible reduction, resided at −1.75 V (vs. Ag/AgCl reference), which is in a proximal potential of proton reduction. Here, we described an electroanalytical approach, combined with liquid phase microextraction (LPME) using ionic liquid (IL), to quantitatively assess trace amount aluminum in environmental samples. The Al(III) was caged by 8-hydroxyquinoline, forming a superb hydrophobic metal⁻chelate, which sequentially transfers and concentrates in the bottom layer of IL-phase during LPME. The preconcentrated Al(III) was further analyzed by a square-wave anodic stripping voltammetry (SW-ASV). The resulting Al-deposited electrodes were characterized by scanning electron microscopy and powder X-ray diffraction, showing the intriguing amorphous nanostructures. The method developed provides a linear calibration ranging from 0.1 to 1.2 ng L^−1 with a correlation coefficient of 0.9978. The LOD attains as low as 1 pmol L^−1, which reaches the lowest report for Al(III) detection using electroanalytical techniques. The applicable methodology was implemented for monitoring Al(III) in commercial distilled water.

A highly selective and sensitive turn-on probe for aluminum(III) based on quinoline Schiff's base and its cell imaging

A reversible Schiff's base fluorescence probe for Al³⁺, (3,5-dichloro-2- hydroxybenzylidene) quinoline-2-carbohydrazide (QC), based on quinoline derivative has been designed, synthesized and evaluated. The QC exhibited a high sensitivity and selectivity toward Al³⁺ in EtOH-H₂O (v/v=1:9, pH=6) by forming a 1:1 complex with Al³⁺ and the detection limit of QC for Al³⁺ was as low as 0.012μM. Furthermore, these results displayed that the binding of QCAl³⁺ was broken by F^-, so this system could be used to monitor F^- in the future. The enhancement fluorescence of the QC could be attributed to the inhibition of PET and ESIPT and the emergency of CHEF process induced by Al³⁺. More importantly, QC was not only successfully used for the determination of trace Al³⁺ in the tap water and the human blood serum, but was valid for fluorescence imaging of Al³⁺ in the Hela cells.

Identification of the Al-binding proteins that account for aluminum neurotoxicity and transport in vivo

Studies have shown that aluminum (Al) is the most abundant neurotoxic element on Earth, and is implicated in the pathogenesis of Alzheimer's disease (AD). However, the mechanisms underlying Al-induced neurotoxicity are still largely elusive. Based on affinity analyses with Al and LC-LTQ-MS, we have found that serum albumin, brain CK-B and 14-3-3ζ protein have a high affinity for Al³⁺, and albumin has a much stronger affinity for Al than transferrin. The normal activity of CK-B, and physiological combination of 14-3-3ζ with tau can be severely perturbed by Al. We anticipate that our assay will provide a new focus concerning the mechanism underlying Al-induced neurotoxicity, and aid the design of strategies to prevent AD and other human diseases related to Al overload.

Determination of Aluminum in Edible Jellyfish Using Chrome Azurol S with Spot Test on Filter Paper

Aluminum (Al) has been well known as an environmental factor that may affect several enzymes and other biomolecules related to Alzheimer's disease. The increasing use of Al in the preparation and storage of food currently represents the main form of Al exposure for the general public. The present study was aimed to develop a household procedure for the rapid test determination of Al in edible jellyfish. The method was developed based on the reaction of Chrome Azurol S with Al in acidic medium, forming a colored compound on the surface of filter paper. Experimental design methodologies were used to optimize the measurement conditions. The proposed method was applied successfully to the analysis of Al in edible jellyfish products in clinical laboratory and household settings.

In vitro adsorption of aluminum by an edible biopolymer poly(γ-glutamic acid)

Accumulation of aluminum in human has been reported to be associated with dementia, Parkinson's disease, and Alzheimer's disease. The objectives of this study were to evaluate an edible biopolymer poly(γ-glutamic acid) (γ-PGA) for aluminum removal efficiency under in vitro conditions as affected by pH, contact time, aluminum concentration, temperature, ionic strength, and essential metals in both aqueous aluminum solution and simulated gastrointestinal fluid (GIF). A low aluminum adsorption occurred at pH 1.5-2.5, followed by a maximum adsorption at pH 3.0-4.0 and precipitating thereafter as aluminum hydroxide at pH > 4. Adsorption was extremely fast with 81-96% of total adsorption being attained within 1 min, reaching equilibrium in 5-10 min. Kinetic data at low (10 mg/L) and high (50 mg/L) concentrations were well described by pseudo-first-order and pseudo-second-order models, respectively. Equilibrium adsorption isotherms at different temperatures were precisely fitted by both Langmuir and Redlich-Peterson models with the maximum adsorption capacities at 25, 37, and 50 °C being 35.85, 38.68, and 44.23 mg/g, respectively. Thermodynamic calculations suggested endothermic and spontaneous nature of aluminum adsorption by γ-PGA with increased randomness at the solid/solution interface. Variation in ionic strengths did not alter the adsorption capacity, however, the incorporation of essential metals significantly reduced the aluminum adsorption by following the order copper > iron > zinc > calcium > potassium. Compared to aqueous solution, the aluminum adsorption from simulated GIF was high at all studied pH (1-4) with Langmuir monolayer adsorption capacity being 49.43 mg/g at 37 °C and pH 4. The outcome of this study suggests that γ-PGA could be used as a safe detoxifying agent for aluminum.

Spectrophotometeric determination of trace amounts of Al3+ ion in water samples after cloud point extraction using quinizarin as a complexing agent

In this study, cloud point extraction was used for the preconcentration of Al(3+) ion after the complex formation with 1,4-dihydroxy-9,10-anthraquinone (Quinizarin [QUIN]), and subsequent analysis by spectrophotometeric method, using Triton X-114 as surfactant. The optimal extraction and reaction conditions were studied (i.e., pH = 5.5, 0.1 mM QUIN, Triton X-114 = 0.1% (w/v)), and the analytical characteristics of the method (e.g., limit of detection, linear range, preconcentration, and enrichment factors) were obtained. Linearity was obeyed in the range of 3.33-166.67 ng ml(-1) of Al(3+) ion. The detection limit of the method was 2.09 ng ml(-1) for Al(3+) ion. The interference effect of some anions and cations was also tested. The method was applied to determine Al(3+) ion in water samples.

Separation/preconcentration methods for the determination of aluminum in dialysate solution and scalp hair samples of kidney failure patients

A new method is reported for the separation of aluminum ions (Al(3+)) from interfering cations in pharmaceutical and biological samples through solid-phase extraction (SPE) using 2-methyl-8-hydroxyquinoline (8-hydroxyquinaldine) on activated silica. While separated Al(3+) was preconcentrated by cloud point extraction (CPE) using 3,5,7,2'-4'-pentahydroxyflavone (morin) as complexing reagent, the resulting complex was entrapped in nonionic surfactant (Triton X-114) as prior step to its determination by spectrofluorimetry (SPF). The validity of separation/preconcentration of Al(3+) was checked by certified reference material of human hair and standard addition method. The chemical variables affecting the analytical performance of the separation/preconcentration methods were studied and optimized. The enrichment factor and detection limit of Al(3+) for the preconcentration of 10 ml of dialysate solution and acid-digested samples of scalp hair samples were found to be 25 and 0.34 μg/L, respectively. The relative standard deviation for six replicates of standard containing 20 μg/L of Al(3+) was <10%. In all DS, the concentration of Al was >10 μg/L. The level of Al in scalp hair samples of kidney failure patients was higher than healthy controls.

Preconcentration, separation and spectrophotometric determination of aluminium(III) in water samples and dialysis concentrates at trace levels with 8-hydroxyquinoline-cobalt(II) coprecipitation system

A separation-preconcentration procedure was developed for the determination of trace amounts of aluminium in water samples and dialysis concentrates by UV-vis Spectrophotometry after coprecipitation using 8-hydroxyquinoline (8-HQ) as a chelating agent and Co(II) as a carrier element. This procedure is based on filtration of the solution containing precipitate on a cellulose nitrate membrane filter following aluminium(III) coprecipitation with Co/8-HQ and then the precipitates together with membrane filter were dissolved in concentrated nitric acid. The metal contents of the final solution were determined by UV-vis Spectrophotometry with Erio Chrome Cyanine-R standard method. Several parameters including pH of sample solution, amount of carrier element and reagent, standing time, sample volume for precipitation and the effects of diverse ions were examined. The enrichment factor was calculated as 50 and the detection limits, corresponding to three times the standard deviation of the blank (N: 10), was found to be 0.2 microg L(-1). The accuracy of the method was tested with standard reference material (CRM-TMDW-500) and spiked addition. Determination of aluminium(III) was carried out in sea water, river water, tap water and haemodialysis fluids samples. The recoveries were >95%. The relative standard deviations of determination were less than 6%.

Separation and preconcentration of aluminum in parenteral solutions and bottled mineral water using different analytical techniques

A new method is reported for the separation of aluminum ions [Al(III)] from interfering elements in parenteral and pharmaceutical solutions (PS) and bottled mineral water (BMW) samples, through solid-phase extraction with 2-methyl-8-hydroxyquinoline (quinaldine) adsorbed onto activated silica gel. While the enrichment step of separated Al(III) was carried out by cloud point extraction (CPE) using 8-hydroxyquinoline as complexing reagent, the resulted complex was entrapped in a non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114). The enriched Al(III) in sample solutions were determined by spectrofluorometry (SPF) at lambda(excitation) 370 nm and lambda(emission) 510 nm, and flame atomic absorption spectrometry (FAAS) for comparative purpose. The variables affecting the complexation and extraction steps were studied and optimized. The validity of methodology was checked with certified reference material of water and standard addition method. The enrichment factor and detection limit of Al(III) for the preconcentration of 50 ml of PS and BMW were found to be 100 and 0.25 microg/L, respectively. The proposed method has been applied for the determination of trace amount of Al(III) in PS and BMW samples with satisfactory results. In PS the levels of Al(III) are above than permissible limit (25 microg/L).

Biosorption of aluminum on Pseudomonas aeruginosa loaded on Chromosorb 106 prior to its graphite furnace atomic absorption spectrometric determination

A biosorption procedure for separation-enrichment of aluminum in environmental samples has been presented in this work. Pseudomonas aeruginosa loaded on Chromosorb 106 has been used as biosorbent for that purpose. P. aeruginosa is a gram-negative, aerobic rod. The influences of pH of the aqueous solution, eluent type, eluent volume, sample volume, etc. were examined on the quantitative recovery of aluminum in P. aeruginosa loaded on Chromosorb 106. The effects of concomitant ions on the recoveries of aluminum were also investigated. The detection limit based on 3 sigma for aluminum is 30 ng L(-1). Three certified reference materials (LGC 6010 Hard Drinking Water, NIST-SRM 1568a Rice Flour and NRCC-DORM-2 Dogfish Muscle) were analyzed for the validation of the presented procedure. The proposed procedure was applied to the determination of aluminum in environmental samples including natural water and food samples. The concentration of aluminum in real samples was found at ppb level.

Determination of trace aluminum in biological and water samples by cloud point extraction preconcentration and graphite furnace atomic absorption spectrometry detection

A cloud point extraction (CPE) method for the preconcentration of trace aluminum prior to its determination by graphite furnace atomic absorption spectrometry (GFAAS) has been developed. The CPE method is based on the complex of Al(III) with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP), and then entrapped in non-ionic surfactant Triton X-114. PMBP was used not only as chelating reagent in CPE preconcentration, but also as chemical modifier in GFAAS determination. The main factors affecting CPE efficiency, such as pH of sample solution, concentration of PMBP and Triton X-114, equilibration temperature and time, were investigated in detail. An enrichment factor of 37 was obtained for the preconcentration of Al(III) with 10 mL solution. Under the optimal conditions, the detection limit of this method for Al(III) is 0.09 ng mL(-1), and the relative standard deviation is 4.7% at 10 ng mL(-1) Al(III) level (n=7). The proposed method has been applied for determination of trace amount of aluminum in biological and water samples with satisfactory results.

A sequential injection method for the fluorimetric determination of aluminum in drinking water using 8-hydroxy-7-(4-sulfo-1-naphthylazo)-5-quinoline sulfonic acid

A robust and simple sequential injection (SI) method for the assay of aluminum ions in drinking water is described. The method is based on the complex formation between aluminum and 8-hydroxy-7-(4-sulfo-1-naphthylazo)-5-quinoline sulfonic acid (HSNQ). The fluorescence of the complex is monitored at an emission wavelength of 492 nm with excitation at 357 nm. The HSNQ concentration, aspirated reagent and sample volumes were optimized simultaneously using 3(3) full factorial design. The optimum operating conditions are aspirated sample and reagent volumes of 90 and 70 microL, respectively, and HSNQ concentration of 20 microM. With these conditions linear calibration curves were obtained from 100 to 800 ppb. The detection limit was 4 ppb. The maximum relative standard deviation of the method was 1.43% (n=5). The method was successfully applied for the determination of aluminum in drinking water samples.

ET-AAS determination of aluminium in dialysis concentrates after continuous flow solvent extraction

Conditions of a continuous flow extraction (CFE) of aluminium acetylacetonate in acetylacetone and aluminium 8-hydroxyquinolinate into methylisobutylketone (lengths of reaction and extraction coils, flow rates of aqueous and organic phases and their flow rate ratio, pH of aqueous phase, lengths of coils for transport of aqueous and organic phases and effect of salts) were studied. The analytical signal of the aluminium chelates present in the organic phase was measured at 309.3 nm using atomic absorption spectrometry with electrothermal atomization (ET-AAS) at the flow rate ratio F aq/F org=3 for aqueous and organic phases. The five points calibration curves were linear (R2 0.9973 and 0.9987) up to 21 microgl(-1) Al with the limits of detection of 0.3 microgl(-1) and the recovery 100+/-2% and precision of 3% at 2-10-fold dilution of the dialysis concentrates. The acetylacetonate method was applied to the determination of aluminium in real dialysis concentrates. Aluminium in concentrations 5-6 microgl(-1) (R.S.D.s 5-10% in real samples) were found and the results were in the very good agreement with those obtained by an ET-AAS using preconcentration of Al(III) on a Spheron-Salicyl chelating sorbent (absolute and relative differences were under 0.4 microgl(-1) and 8.2%, respectively).

Extraction spectrophotometric determination of aluminum in dialysis concentrates with 3,5-ditertbutylsalicylfluorone and ionic liquid 1-butyl-3-trimethylsilylimidazolium hexafluorophosphate

The paper describes a highly sensitive and selective extraction spectrophotometric method for determination of aluminum in dialysis concentrates with new reagent 3,5-ditertbutylsalicylfluorone abbreviated as DTBSF, in which the ionic liquid 1-butyl-3-trimethylsilylimidazolium hexafluorophosphate abbreviated as [C4tmsim][PF6] was used as novel medium for liquid/liquid extraction of aluminum(III). Under optimal condition, DTBSF reacted with aluminum(III) to form a neutral Al-DTBSF complex rapidly, the complex was then extracted into the [C4tmsim][PF6] phase, the absorbance of the complex in ionic liquid at 542 nm was recorded and used to determine aluminum(III). The apparent molar absorptivity of the complex and detection limit were found to be 3.52x10(6) l mol(-1) cm(-1) and 0.06 microg/l, respectively. The absorbance of the complex at 542 nm increases linearly with the concentration of aluminum(III) up to 3 microg of aluminum(III) in 250 ml of aqueous solution. The interference study show the determination of aluminum is free from interferences of almost all positive and negative ions found in dialysis concentrate samples. The determination of aluminum in dialysis concentrates were carried out by the present method and electrothermal atomic absorption spectrometry (GTAAS). The results were satisfactorily comparable so that the applicability of the proposed method with the ionic liquid system was also investigated. Moreover, the synthesis of and conditions for the formation and extraction of Al-DTBSF complex were investigated as well.

The sensitive and selective determination of aluminium by spectrofluorimetric detection after complexation with N-o-vanillidine-2-amino-p-cresol

A simple, easy to use and selective spectrofluorimetric method for the determination of trace levels of aluminium has been developed. A new Schiff base, N-o-vanillidine-2-amino-p-cresol (OVAC), has been synthesized and its fluorescence activity with aluminium investigated. Based on this chelation reaction, a spectrofluorimetric method has been developed for the determination of aluminium in samples buffered at pH 4.0 using acetic acid-sodium acetate. The chelation reaction between Al(iii) and N-o-vanillidine-2-amino-p-cresol was very fast, requiring only 20 min at room temperature to complex completely. The excitation and emission wavelengths were 423.0 and 553.0 nm, respectively, at which the OVAC-Al complex gave the maximum fluorescence intensity at pH 4.0 in a 50% ethanol-50% water medium. The interference from fluoride ions was minimized by the addition of Be(2+). Other ions were found not to interfere at the concentrations likely to be found in natural waters. Under these conditions, the calibration plot was linear up to 1000 microg L(-1) (r = 0.999). The limit of detection (3sigma) for the determination of Al(iii) was 0.19 microg L(-1) and the precision for multiple determinations of 3 ng mL(-1) Al(iii) prepared in ultra-pure water was found to be 0.29% (n = 16). The Schiff base ligand could be used to determine ultra-trace aluminium from natural waters. Analysis of environmental certified reference materials showed good agreement with the certified values. The procedure was found to be equally applicable to both fresh water and saline solutions (including sea water) using either normal external calibration or the standard additions method.