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

A novel ratiometric sensor for fluorimetric and visual dual-mode detection of Al3+ in environmental water based on the target-regulated formation of Eu MOFs

Herein, a novel ratiometric sensor for fluorimetric and smartphone-assisted visual detection of Al3+ in environmental water was developed based on the target-regulated formation of Eu metal-organic frameworks (Eu MOFs). By employing 2-[4-(2-hydroxyethyl) piperazin-1-yl] ethanesulfonic acid (Hepes), Eu3+ and tetracycline (TC) as raw materials, Eu MOFs with red emission were facilely synthesized through the coordination of Eu3+ with Hepes and TC. However, upon the introduction of Al3+, a higher affinity of TC towards Al3+ resulted in the formation of a TC-Al3+ complex with green fluorescence and inhibited the generation of Eu MOFs. This led to an increase in green fluorescence and a decrease in red fluorescence accompanied by the fluorescence color of the solution changing from red to green under the illumination of the UV lamp. Thus, a ratiometric sensor for fluorimetric and the smartphone-assisted visual detection of Al3+ was established. The ratiometric sensor exhibited high sensitivity for Al3+ detection with a detection limit of 0.14 μM for fluorescence detection and 1.21 μM for visual detection. Additionally, the proposed strategy was successfully applied to detect Al3+ in the environmental water samples with satisfactory results, indicating great application prospects for environmental monitoring.

Smartphone Digital Image Colorimetry for the Determination of Aluminum in Antiperspirant Products

Objectives

This study aims to present a method for the determination of the aluminum in antiperspirant products (APPs) by chelating it with quercetin before its detection by smartphone digital image colorimetry (SDIC).

Materials and Methods

Samples were prepared by closed-vessel acid digestion in PTFE cups. This was followed by complexation of aluminum in the sample solution using quercetin as a chelating agent. Sample solutions were transferred into a quartz ultraviolet/visible detection microcuvette for detection in a homemade colorimetric box designed for capturing images of the yellow complex with a smartphone camera. The pixel intensity of the images was converted to numbers for quantitation using ImageJ software for a personal computer. An independent study using high-performance liquid chromatography-diode-array detection was conducted to check the accuracy of the proposed method.

Results

Optimum SDIC conditions included a Samsung C9 smartphone as the detection camera, a cropped region of interest of 6400 px², and the side position of the colorimetric box were selected for capturing the images of the sample solutions placed 10.0 cm from the detection camera, whereas optimum complexation conditions were found to be as sample pH of 5.5, sample volume of 3.0 mL, complexation time of 1.0 min and a ligand concentration of 0.28 mmol L^-1. Analytical performance of the method included a limit of detection of 0.5 μmol L^-1 and a coefficient of determination (R²) of the calibration graph of 0.9981.

Conclusion

The proposed method was successfully applied for the determination of aluminum in APPs with percentage recoveries ranging from 80.0 to 109.6%.

A simple "turn-on" fluorescent sensor for reversible recognition of aluminum ion in living cell

A simple and reliable "turn-on" fluorescent sensor (E)-1-[((2-hydroxyethyl)imino) methyl] naphthalen-2-ol (HNP) has been designed, synthesized, and characterized by ¹H-NMR, ¹³C-NMR, FT-IR, and EI-MS analysis. The binding property of HNP was examined employing UV-Vis and fluorescence spectroscopy. HNP exhibited high selectivity towards Al³⁺ among other cations and anions. The fluorescence titration experiment has established binding stoichiometry of HNP with Al³⁺ is 2:1, which can be further verified by HR-MS. The detection limit of HNP is 2.9 μM, and it can be reversible five-to-seven times to detect Al³⁺ without losing much efficiency which indicates that it can be a reliable probe for Al³⁺. Additionally, HNP was successfully applied for the detection of Al³⁺ in living cells. To achieve the detection of aluminum ion across a simple, reliable, and precise method, we have investigated the reversible detection (which can reversible response to Al³⁺ for five-to-seven times) of Al³⁺ through an extremely simple (requires only one-step reaction) "turn-on" fluorescent probe which enables us to visualize and analyze Al³⁺ with low detection limit (2.9 μM) and high selectivity in living cell without interference from the high abundant small biological molecules.

A naphthalene-based azo armed molecular framework for selective sensing of Al3+

A naphthalene-based azo armed molecular derivative was synthesized for sensing of Al3+ and cell imaging studies. The fluorescence enhancement is caused by restricted CN isomerization, CHEF on, and PET-off processes.

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.

2-Hydroxynaphthalene based acylhydrazone as a turn-on fluorescent chemosensor for Al3+ detection and its real sample applications

Developing high performance fluorescent chemosensor for Al³⁺ detection is highly desirable, due to the excess of Al³⁺ will lead to many diseases. In this paper, a simple 2-hydroxynaphthalene-based fluorescent chemosensor has been synthesized and characterized by different spectroscopic methods. The compound exhibited an "turn-on-type" fluorescent chemosensing for the detection of Al³⁺, which was ascribed to the chelation-enhanced fluorescence (CHEF). The high selectivity and sensitivity of the compound for Al³⁺ were verified by fluorescence spectra in its DMF solution, and the enhancement of fluorescent intensity could be observed by naked-eye from non-fluorescence to green light. The detection limit of the compound for Al³⁺ was found to be 4.22 × 10^-8 M and the stability constant was 4.82 × 10⁴ M^-1. The 1:1 binding stoichiometry of the compound to Al³⁺ was confirmed from the Job's plot based on fluorescence titrations. Additionally, the sensing process of the compound to Al³⁺ was chemically reversible by adding Na₂EDTA. Importantly, the probe was successfully applied to quantitative analysis of Al³⁺ in real drug and potable water samples.

A purine based fluorescent chemosensor for the selective and sole detection of Al3+ and its practical applications in test strips and bio-imaging

A novel purine Schiff base fluorescent probe (WYW), (E)-4-methyl-2-((2-(9-(naphthalen-1-yl)-8-(thiophen-2-yl)-9H-purin-6-yl)hydrazono)methyl)phenol, was designed and prepared as an excellent reversible fluorescent chemosensor for monitoring Al³⁺. The fluorogenic "turn-on" sensor WYW exhibited high selectivity towards Al³⁺ over other coexistent metal ions, accompanying with an obvious visual color change in DMSO/H₂O (9/1, v/v, pH = 7.4) media. The enhancement fluorescence of WYW could be attributed to the inhibition of PET and ESIPT process induced by Al³⁺. Notably, the WYW-Al³⁺ complex exhibited a fluorescence "turn-off" response towards F^- with exceptional selectivity via the displacement approach. The detection limit of WYW for Al³⁺ was calculated to be as low as 82 nM. The formation of complex WYW-Al³⁺ (1:1 stoichiometry) was confirmed by Job's methods and further verified by density functional theory (DFT) calculations. Furthermore, the probe WYW with low cytotoxicity and excellent membrane-permeable property has also been successfully applied for detecting low concertation Al³⁺ in living HeLa cells.

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.

Study on synthesis and fluorescence property of rhodamine-naphthalene conjugate

In this study, a novel ligand (HL) consisting of 2-methyl quinoline-4-carboxylic acid, rhodamine and naphthalene moiety, was designed and synthesized, it could be developed a ratiometric fluorescent sensor for selective detection of Al³⁺ via fluorescence resonance energy transfer (FRET) from naphthalimide moiety to rhodamine moiety. The addition of Al³⁺ trigger the significant fluorescence enhancement of HL at 550 nm at the expense of the fluorescent emission of HL centered at 524 nm.

Coumarin-based colorimetric-fluorescent sensors for the sequential detection of Zn2+ ion and phosphate anions and applications in cell imaging

Two novel coumarin based fluorescent sensors CHP and CHS have been synthesized for the sequential detection of Zn²⁺ ion and phosphate anion (PA) in DMF/HEPES buffer medium (1/5 v/v, 10 mM, pH = 7.4). On the addition of Zn²⁺ ion to the solution of CHP or CHS resulted in a pronounced fluorescence enhancement, accompanying noticeable color change (under UV or daylight), while there was hardly obvious change with other competing metal ions co-existing. The detection limits (DL) of CHP and CHS toward Zn²⁺ were separately determined as 1.03 × 10^-7 (R² = 0.9886) and 1.87 × 10^-7 (R² = 0.9902). The PET binding processes were affirmed by spectroscopic techniques, HRMS experiments and theoretical calculations. Subsequently, the CHP-Zn²⁺ or CHS-Zn²⁺ complexes showed high selectivity fluorescence quenching toward PA by snatching Zn²⁺ ion from its complex and the binding processes were reversible. DLs were calculated as 2.07 × 10^-7 M (R² = 0.9928) and 2.63 × 10^-7 M (R² = 0.9954), respectively. Furthermore, the cell imaging experiments demonstrated that the sensors were capable of detecting of Zn²⁺ and PA in vitro cells.

An efficient water-soluble fluorescent chemosensor based on furan Schiff base functionalized PEG for the sensitive detection of Al3+ in pure aqueous solution

An efficient reversible fluorescent chemosensor, PEGFB, based on polyethylene glycol bearing a furan Schiff base unit has been successfully developed to sensitively detect Al³⁺ in pure aqueous solution.

A high performance 2-hydroxynaphthalene Schiff base fluorescent chemosensor for Al3+ and its applications in imaging of living cells and zebrafish in vivo

Developing high performance fluorescent chemo-sensors for in vitro and in vivo Al³⁺ detection is highly desirable, because Al³⁺ accumulation has been involved to various diseases. Herein, we report a highly selective and sensitive Schiff base fluorescent probe, H₃L, based on 2-hydroxynaphthalene, which can recognize aluminum ions and exhibit an "off-on" mode with high selectivity in methanol solutions. The detection limit of the probe for Al³⁺ is as low as 10^-7 M which was determined by fluorescent titration. The high selectivity and high sensitivity of H₃L for Al³⁺ are attributed to the inhibition of ESIPT. Additionally, the distribution of intracellular Al³⁺ ions could be observed under confocal fluorescence microscopy. Moreover, we also applied H₃L for in vivo detection of Al³⁺ ions in living zebrafish larvae.

A new Al3+ selective fluorescent turn-on sensor based on hydrazide-naphthalic anhydride conjugate and its application in live cells imaging

In this communication, we have developed an optical chemosensor 2-amino N-(6-bromo-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)benzamide (NAPH) for selective detection of Al³⁺ by reacting 4-bromo-1,8-naphthalic anhydride with 2-aminobenzohydrazide. In (DMSO:H₂O, 1:1, v/v) medium, the selective and specific nature of NAPH towards Al³⁺ was observed by the quenching along with a blue-shift in the absorption of NAPH at 465 nm that resulted in the distinct colour change from light brown to colourless. The selective complexation that occurred between NAPH and Al³⁺ was investigated by ¹H NMR and DFT methods. Under similar conditions, the weakly fluorescent receptor NAPH showed a distinct fluorescence enhancement at 555 nm in the presence of Al³⁺ among the other tested metal ions and anions. The NAPH·Al³⁺ complex formation is reversible upon addition of strong chelating agent EDTA. The receptor NAPH can be applied to detect Al³⁺ down to 2.9 μM without any interference from other tested metal ions. In addition, the receptor NAPH was successfully applied to detect Al³⁺ in live HeLa cells.

HPLC Identification of Copper (II)-Trans-Resveratrol Complexes in Ethanolic Aqueous Solution

Reversed-phase high-performance liquid chromatography assay with the diode array detector was applied for detection of trans-resveratrol complexes with copper (II). Two complexes with copper to resveratrol ratio 3:2 and 1:1 were identified in ethanolic-aqueous solutions in neutral and acidic conditions. The matrix-assisted laser desorption ionization-time of flight mass spectrometry was used for evaluation of complexes in eluate liquid fraction. The structures of complexes were modeled by Titan, Spartan and HyperChem software. The findings obtained satisfactorily explain the chromatographic data and could provide useful an additional data about these forms in which is present trans-resveratrol in wine (free and/or forming complex with copper).

A Review on Recent Applications of High-Performance Liquid Chromatography in Metal Determination and Speciation Analysis

High-performance liquid chromatography (HPLC) has several advantages over the conventional methods due to their operational simplicity. It is a vital tool to determine metal ions having same mass but different electronic configuration, to separate complex mixtures and to resolve ions that may be indistinguishable by mass spectrometry alone. Metal ions play vital role in many biological processes and involved in setting up of many diseases. Therefore, the development of simple methods for the detection and quantification of metals in real samples might serve as diagnostic tools for various diseases. This review article focuses on the recent main feature of this technique, i.e. speciation of metal ions and their applications to series of problem of metal ion chemistry in different environmental matrixes. Speciation of metals is of increasing interest and has a great importance because of bioavailability, environmental mobility, toxicity and potential risk of metals. With the capability of partitioning the complex species of different metal ions, HPLC is an efficient technique for this task. This review summarizes recent advances in the development of HPLC to the fundamental understanding of metal ion chemistry in the environment and discusses all the issues that still need a lot of consideration. It has been classified into different sections depending on the role of HPLC in separation used and metal speciation; furthermore, the underlying sample preconcentration techniques and detection systems involved for the determination of metal ions and their applications were discussed.

A simple and rapid method for direct determination of Al(III) based on the enhanced resonance Rayleigh scattering of hemin-functionalized graphene-Al(III) system

A novel method for direct determination of Al(III) by using hemin-functionalized graphene (H-GO) has been established based on the enhancement of resonance Rayleigh scattering (RRS) intensity. The characteristics of RRS spectra, the optimum reaction conditions, and the reaction mechanism have been investigated. In this experiment, the Al(III) would exist in sol-gel Al(OH)3 species under the condition of pH5.9 in aqueous solutions. When H-GO existed in the solution, the sol-gel Al(OH)3 would react with H-GO and result in enhancement of RRS intensity, owing to the enhanced hydrophobicity of H-GO surface. Therefore, a simple and rapid sensor for Al(III) was developed. The increased intensity of RRS is directly proportional to the concentration of Al(III) in the range of 10 nM-6 μM, along with a detection limit of 0.87 nM. Moreover, the sensor has been applied to determination of Al(III) concentration in real water and aspirin tablet samples with satisfactory results. Therefore, the proposed method is promising as an effective means for selective and sensitive determination of Al(III).

Visual detection of Al(3+) ions using conjugated copolymer-ATP supramolecular complex

A colorimetric Al(3+) sensor based on fluorescence recovery of a conjugated copolymer-ATP complex is proposed. An optimized ratio of two polythiophene (PT) monomers is utilized to synthesize copolymer (CP) that yielded maximized colorimetric response for Al(3+) in deionized (DI) and tap water. The electrostatic disassembly of CP-ATP upon addition of Al(3+) led to an evident visual color change. The lowest concentration of Al(3+) for naked eye observation is around 4 μM, which is below the threshold levels in drinking water according to European Economic Community (EEC) standard. Besides, the proposed assay showed a similar response to Al(3+) in tap water. The proposed methodology showed selective and sensitive detection for Al(3+) in analytically relevant concentration ranges without involving sophisticated instrumentation, illustrating the applicability for on-site drinking water monitoring.

A selective colorimetric and fluorescent sensor for Al3+ ion and its application to cellular imaging

A new rhodamine-based fluorescent turn-on chemosensor (L) for selective detection of Al3+ ion has been developed and characterized. The fluorescent chemosensor L was synthesized by the reaction of intermediate (4) with 2,5-bis (4-phenylacyl chloride)-1,3,4-oxadiazole (3). The chemosensor L displays an excellent selective and sensitive response to Al3+ ion over other metal ions, in which the spirocyclic (non-fluorescent) to ring opened amide (fluorescent) process was utilized and a 1:2 stoichiometry for L-Al3+ complex was formed with an association constant of 2.03×10(3) M(-1). Furthermore, chemosensor L can be applied as a fluorescent probe for monitoring Al3+ in living cells by performing cell imaging studies.

Two Different Emission-Wavelength Fluorescent Probes for Aluminum Ion based on Tunable Fluorophores in Aqueous Media

Two simply and highly selective aluminium ion fluorescent probes based on 4-aminoantipyrine derivate have been successfully synthesized and systemically characterized, The investigation of absorption and emission spectra revealed that the compounds exhibited highly selective fluorescence behaviours toward Al(3+) in aqueous media and showed differential fluorescent emission peaks corresponding to blue and green. which resulted from different fluorophores, and the fluorescence process is attributed to the Photoinduced Electron Transfer (PET) mechanism, In addition, the association constants between sensors L1 and L2 with aluminum ion are 1.58 × 10(6) M(-1) and 8.72 × 10(6) M(-1), respectively, which were obtained by fluorescent titration experiments. Moreover, the binding site of sensors with Al(3+) were determined by (1)HNMR titration experiments.

Specific fluorescent sensing of aluminium using naphthalene benzimidazole derivative in aqueous media

Naphthalene benzimidazole conjugate bearing a hydroxyl group was synthesized. Its binding properties towards various metal ions were examined and it showed a high selectivity and sensitivity towards Al(3+) ions in aqueous media. The recognition processes follows a photo induced electron transfer (PET) mechanism assisted with the restricted intramolecular C-C single bond rotation and are scarcely influenced by other coexisting metal ions. In addition, determination of Al(3+) in a variety of sewage water samples was also determined.

Design and construction of new potentiometric sensors for determination of Al3+ ion based on (Z)-2-(2-methyl benzylidene)-1-(2,4-dinitrophenyl) hydrazine

(Z)-2-(2-methyl benzylidene)-1-(2,4-dinitrophenyl) hydrazine (L) was used as an active component of PVC membrane electrode (PME), coated graphite electrode (CGE) and coated silver wire electrode (CWE) for sensing Al(3+) ion. The electrodes exhibited linear Nernstian responses to Al(3+) ion in the concentration range of 1.0×10(-6) to 1.0×10(-1)M (for PME, LOD=8.8×10(-7)M), 5.5×10(-7) to 2.0×10(-1)M (for CWE, LOD=3.3×10(-7)M) and 1.5×10(-7) to 1.0×10(-1)M (for CGE, LOD=9.2×10(-8)M). The best performances were observed with the membranes having the composition of L:PVC:NPOE:NaTPB in the ratio of 5:35:57:3 (w/w; mg). The electrodes have a response time of 6s and an applicable pH range of 3.5-9.1. The sensors have a lifetime of about 15weeks and exhibited excellent selectivity over a number of mono-, bi-, and tri-valent cations including alkali, alkaline earth metal, heavy and transition metal ions. Analytical utility of the proposed sensor has been further tested by using it as an indicator electrode in the potentiometric titration of Al(3+) with EDTA. The electrode was also successfully applied for the determination of Al(3+) ion in real and pharmaceutical samples.

Pre-Column Derivatization HPLC Procedure for the Quantitation of Aluminium Chlorohydrate in Antiperspirant Creams Using Quercetin as Chromogenic Reagent

This article describes the development and validation of a selective high-performance liquid chromatography method that allows, after liquid–liquid extraction and pre-column derivatization reaction with quercetin, the quantification of aluminium chlorohydrate in antiperspirant creams. Chromatographic separation was achieved on an XTerra MS C18 analytical column (150 × 3.0 mm i.d., particle size 5 μm) using a mobile phase of acetonitrile:water (15:85, v/v) containing 0.08 % trifluoroacetic acid at a flow rate of 0.30 mL min⁻¹. Ultraviolet spectrophotometric detection at 415 nm was used. The assay was linear over a concentration range of 3.7–30.6 μg mL⁻¹ for aluminium with a limit of quantitation of 3.74 μg mL⁻¹. Quality control samples (4.4, 17.1 and 30.6 μg mL⁻¹) in five replicates from five different runs of analysis demonstrated intra-assay precision (% coefficient of variation <3.8 %), inter-assay precision (% coefficient of variation <5.4 %) and an overall accuracy (% recovery) between 96 and 101 %. The method was used to quantify aluminium in antiperspirant creams containing 11.0, 13.0 and 16.0 % (w/w) aluminium chlorohydrate, respectively.

A napthelene–pyrazol conjugate: Al(iii) ion-selective blue shifting chemosensor applicable as biomarker in aqueous solution

A new crystallographically characterized napthelene–pyrazol conjugate acts as an Al(III) ion selective chemosensor in 100 mM HEPES buffer (water–DMSO 5 : 1, v/v) at biological pH. It is an efficient biomarker in detecting Al(III) ions in living cells.

A FRET-based ‘off–on’ molecular switch: an effective design strategy for the selective detection of nanomolar Al3+ ions in aqueous media

A FRET-based ratiometric chemosensor (L1) is highly selective for Al³⁺ ions (as low as 6.19 × 10⁻⁹ M) and could be used to acquire images of Al³⁺ ions in living cells.

Spectrofluorimetric determination of aluminum ions via complexation with luteolin in absolute ethanol

An optimized and validated spectrofluorimetric method has been developed for the rapid determination of aluminum in absolute ethanol. The method is based on the chelation of aluminum and luteolin which results in a complex exhibiting an intense emission signal. The characterization of Al-luteolin complex was studied using ultraviolet-visible spectrometry, infrared spectrometry, fluorescence and mass spectrometry. The complex stoichiometry ratio of aluminum:luteolin was 1:2. The fluorescence of the complex was monitored at an emission wavelength of 545 nm with excitation at 518 nm. The linear concentration range was 6.5 × 10(-7) to 4.0 × 10(-5)  M with a correlation coefficient of r = 0.998. The detection limit was 5.0 × 10(-7)  M. The method was appropriately validated and yielded relative standard deviations of < 2.3% (n = 5), which was considered acceptable. The method was successfully applied in the determination of aluminum in river water, skin care products and pharmaceutical samples.

A water soluble Al3+ selective colorimetric and fluorescent turn-on chemosensor and its application in living cell imaging

An efficient water soluble fluorescent Al(3+) receptor, 1-[[(2-furanylmethyl)imino]methyl]-2-naphthol (1-H) was synthesized and characterized by physico-chemical and spectroscopic tools along with single crystal X-ray crystallography. High selectivity and affinity of 1-H towards Al(3+) in HEPES buffer (DMSO/water: 1/100) of pH 7.4 at 25 °C showed it to be suitable for detection of intracellular Al(3+) by fluorescence microscopy. Metal ions, viz. alkali (Na(+), K(+)), alkaline earth (Mg(2+), Ca(2+)), and transition-metal ions (Ni(2+), Zn(2+), Cd(2+), Co(2+), Cu(2+), Fe(3+), Cr(3+/6+), Hg(2+)) and Pb(2+), Ag(+) did not interfere. The lowest detection limit for Al(3+) was calculated to be 6.03 × 10(-7) M in 100 mM HEPES buffer (DMSO/water: 1/100). Theoretical calculations have also been included in support of the configuration of the probe-aluminium complex.

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.