Preconcentration Capacity Research Articles

Nanogold amplified electrochemiluminescence/electrochemistry in bipolar silica nanochannel array for ultrasensitive detection of SARS-CoV-2 pseudoviruses

The prompt and accurate point-of-care test (POCT) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in infected persons or virus-containing environmental samples is of great importance. The present work reports a highly integrated electrochemiluminescence/electrochemical (ECL/EC) sensor for determination of SARS-CoV-2 pseudoviruses, in which bio-recognition element (SARS-CoV-2 IgG antibody), bifunctional probe (tris (2,2′-bipyridyl) ruthenium (Ru(bpy)32+)), and amplification material (gold nanoparticles (Au NPs)) are designed into bipolar silica nanochannel array (bp-SNA). bp-SNA consisting of homogeneous two-layer mesoporous silica films bears inner silanol groups and outer amino groups, generating a solid “electrostatic nanocage” for stable confinement of Ru(bpy)32+ and Au NPs inside the nanochannels and further providing functional sites for covalent modification of SARS-CoV-2 IgG antibody. Owing to the preconcentration capacity of bp-SNA and amplified effect of Au NPs, ECL or EC signals of Ru(bpy)32+ can be remarkably promoted and thereby increase the analytical performance, which can be diminished by immunorecognization of target SARS-CoV-2 pseudoviruses on the sensing interface. The developed integrated ECL/EC sensor based on Ru@AuNPs/bp-SNA modified solid indium tin oxide electrode enables the sensitive analysis of SARS-CoV-2 pseudoviruses by ECL mode with a linear range of 50 TU mL−1–5000 TU mL−1, as well as the EC mode with a linear range of 100 TU mL−1–5000 TU mL−1. Moreover, the designed sensor showed satisfactory results in the analyses of saliva and pond water samples. When flexible electrode substate (polyethylene terephthalate) is employed, Ru@AuNPs/bp-SNA has great potential to integrate with KN95 face masks for direct detection of SARS-CoV-2 pseudoviruses produced from breathing, talking and coughing processes, which could provide an efficient platform for POCT diagnosis.

Magnetic graphene oxide and vertically-ordered mesoporous silica film for universal and sensitive homogeneous electrochemiluminescence aptasensor platform

Herein, we demonstrated a convenient and highly sensitive homogeneous electrochemiluminescence (ECL) aptasensor platform by combination of magnetic composite probe and vertically-ordered mesoporous silica films (VMSF). Magnetic composite probe composed of biorecognition element (target-specific aptamer), ECL signal reporter (Ru(bpy)32+) and large-scale magnetic graphene oxide (M−GO), can be prepared by simple incubation, magnetic separation and redispersion prior to use. High-affinity and specific binding between target and aptamer can detach aptamer from M−GO and simultaneously release the slight amount of Ru(bpy)32+ into a solution, which can be sensitively detected by VMSF modified indium tin oxide (VMSF/ITO) due to the excellent electrostatic preconcentration capacity of VMSF. In this sensing system, detectable signal of Ru(bpy)32+ can be remarkably amplified by VMSF/ITO and meanwhile background signal can be reduced by the adsorption capacity of M−GO and size exclusion property of VMSF/ITO, effectively promoting the analytical performance of the present homogeneous ECL aptasensor. The applicability and universality of this sensing platform was confirmed by employing alpha fetoprotein (AFP) and prostate specific antigen (PSA) as the target models and their detection limits were 0.08 pg/mL and 9.6 pg/mL, respectively. Furthermore, the designed homogeneous ECL aptasensor platform is label-free, immobilization-free, low-cost, and free of additional electrode modification and sample pretreatment procedures, rendering a simple sensing strategy for quantitative determination of various biomarkers in clinical diagnosis by adapting the specific aptamer.

Magnetic tubular nickel@silica-graphene nanocomposites with high preconcentration capacity for organothiophosphate pesticide removal in environmental water: Fabrication, magnetic solid-phase extraction, and trace detection

Organothiophosphate pesticides (OPPs) are the most common water contaminants, significantly endangering human health and bringing serious public safety issues. Thus, developing effective technologies for the removal or trace detection of OPPs from water is urgent. Herein, a novel graphene-based silica-coated core–shell tubular magnetic nanocomposite (Ni@SiO2-G) was fabricated for the first time and used for the efficient magnetic solid-phase extraction (MSPE) of the OPPs chlorpyrifos, diazinon, and fenitrothion from environmental water. The experimental factors affecting extraction efficiency such as adsorbent dosage, extraction time, desorption solvent, desorption mode, desorption time, and adsorbent type were evaluated. The synthesized Ni@SiO2-G nanocomposites showed a higher preconcentration capacity than the Ni nanotubes, Ni@SiO2 nanotubes, and graphene. Under the optimized conditions, 5 mg of tubular nano-adsorbent displayed good linearity within the range of 0.1–1 μg·mL–1, low limits of detection (0.04–0.25 pg·mL–1), low limits of quantification (0.132–0.834 pg·mL−1), good reusability (n = 5; relative standard deviations between 1.46% and 9.65%), low dosage (5 mg), and low real detection concentration (< 3.0 ng·mL−1). Moreover, the possible interaction mechanism was investigated by density functional theory calculation. Results showed that Ni@SiO2-G was a potential magnetic material for the preconcentration and extraction of formed OPPs at ultra-trace levels from environmental water.

An ultralight and flexible nanofibrillated cellulose/chitosan aerogel for efficient chromium removal: Adsorption-reduction process and mechanism

Heavy metals in water are critical global environmental problems. In particular, the anionic heavy metal chromium (Cr) has carcinogenic and genotoxic risks on human health. To this end, an ultralight and flexible nanofibrillated cellulose (NFC)/chitosan (CS) aerogel was developed only by freeze-drying combined with physical thermal cross-linking for efficient one step co-removal of Cr(VI) and Cr(III). The maximum adsorption capacity of Cr(VI) and total Cr calculated according to the Langmuir model was 197.33 and 134.12 mg/g, respectively. Even in the presence of competing soluble organics, anions and oil contaminants, the resulting NFC/CS-5 aerogels showed excellent selectivity. The aerogel exhibited outstanding mechanical integrity, remaining intact after 17 compressions in air and underwater. Meanwhile, after 5 adsorption-desorption cycles, the aerogel was easy to regenerate and maintained a high regeneration efficiency of 80.25%. Importantly, self-assembled NFC/CS-5 aerogel filter connected with the peristaltic pump could purify 752 mL of industrial wastewater with Cr(VI) pre-concentration capacity of 49.71 mg/g. XPS and FT-IR verified that electrostatic interactions, reduction and complexation acted as the main driving forces for the adsorption process. Moreover, such aerogel possessed broad application prospects for alleviating heavy metal pollution in agriculture.

Introduction of a biowaste/graphene oxide nanocomposite as a coating for a metal alloy based SPME fiber: Application to screening of polycyclic aromatic hydrocarbons

The present study introduces a high efficiency metal alloy-based solid-phase microextraction (SPME) fiber coated with a green biowaste nanocomposite of chicken feet yellow membrane mixed with graphene oxide (CFYM/GO). An Al/Cr commercial heating element (aluchrom, AC) has been selected as the fiber substrate and designed as coiled form (CAC-SPME) to enhance its extraction and pre-concentration capacity. The fabricated fiber, CAC-SPME/CFYM/GO, has been employed for the extraction and pre-concentration of some commonly seen PAHs in different standard/real samples prior to their high performance liquid chromatography- ultraviolet (HPLC-UV) analyzing. The synthesized materials and the fibers surface were characterized by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy analysis and Brunauer-Emmett-Teller surface area analysis. Under the optimized experimental conditions, low detection limits (LOD, 0.039–0.30 µg L–1), wide linear ranges (LR, 0.13–643 µg L–1) and good relative recoveries (RR, 76.20–105.60%) were achieved for all the target analytes. The materials applied to prepare this fiber were low-priced and accessible and also eliminated the need for expensive coating substances. In addition, using of the AC alloy substrate was increased the fiber physicochemical resistance and solved the breakage drawback of the conventional SPME fibers. Moreover, simple fabrication, high rigidity, long service life and high extraction capacity were some of the other advantages of the suggested fiber. Therefore, the proposed method can be utilized successfully for the routine analysis of PAHs in different matrixes.

Electroanalytical Determination of Cd(II) and Pb(II) in Bivalve Mollusks using Electrochemically Reduced Graphene Oxide‐based Electrode

AbstractAn electrochemical sensor for the simultaneous determination of Cd(II) and Pb(II) by square wave anodic stripping voltammetry (SWASV) in bivalve mollusks using a glassy carbon electrode modified with electrochemically reduced graphene oxide has been developed. The modified surface was characterized by cyclic voltammetry, high resolution scanning electron microscopy (HR‐SEM), and Raman spectroscopy. The optimum conditions were optimized and a linear range was observed from 15–105 μg L−1 with a limits of detection of 15 μg L−1 for Cd(II) and Pb(II). The methodology was validated and applied in different samples of commercial bivalve mollusks with satisfactory results. The high conductivity and greater surface area of the modifying agent improves the preconcentration capacity of the electrochemical sensor, allowing to develop a simple, rapid and sensitive analysis in the detection of lead and cadmium in marine resources.

A new hybrid sorbent 2,2’-pyridil functionalized SBA-15 (Pyl-SBA-15) synthesis and its applications in solid phase extraction of Cu(II) from water samples

A mesoporous hybrid material, 2,2’-Pyridil-SBA-15 (Pyl-SBA-15) was synthesized by anchoring 2,2’-Pyridil onto the surface of SBA-15. The application of Pyl-SBA-15 as a sorbent in separation and preconcentration of Cu(II) ions in water samples was studied. Effect of different parameters like pH, volume of eluent, sample flow rate and interfering ions was investigated. The preconcentration capacity value of the prepared material under optimized conditions for Cu(II) was 0.88 ± 0.01 mmol g−1. The Cu(II) ions collected onto the sorbent were eluted out with 6 mL of 1 M HNO3 and determined by atomic absorption spectroscopy (AAS). The enrichment factor and detection limit of Cu(II) were found to be 66.6 and 0.38 μg L-1 respectively.

Electrochemical Deposition of Gold Nanoparticles on Reduced Graphene Oxide by Fast Scan Cyclic Voltammetry for the Sensitive Determination of As(III).

In this study, a stable, sensitive electrochemical sensor was fabricated by the electrochemical codeposition of reduced graphene oxide (rGO) and gold nanoparticles on a glassy carbon electrode (rGO-Aunano/GCE) using cyclic voltammetry (CV), which enabled a simple and controllable electrode modification strategy for the determination of trace As(III) by square wave anodic stripping voltammetry (SWASV). SWASV, CV, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the electrochemical properties and morphology of the proposed sensing platform. The number of sweep segments, the deposition potential and the deposition time were optimized to obtain ideal sensitivity. The presence of rGO from the electroreduction of graphene oxide on the sensing interface effectively enlarged the specific surface area and consequently improved the preconcentration capacity for As(III). The rGO-Aunano/GCE sensor exhibited outstanding detection performance for As(III) due to the combined effect of Aunano and rGO formed during the electroreduction process. Under the optimized conditions, a linear range from 13.375 × 10−9 to 668.75 × 10−9 mol/L (1.0 to 50.0 μg/L) was obtained with a detection limit of 1.07 × 10−9 mol/L (0.08 μg/L) (S/N = 3). The reproducibility and reliability of the rGO-Aunano/GCE sensor were also verified by performing 8 repetitive measurements. Finally, the rGO-Aunano/GCE sensor was used for the analysis of real samples with satisfactory results.

Synthesis and characterization of the first cyrhetrenyl-appended calix[4]arene macrocycle and its application as an electrochemical sensor for the determination of Cu(II) in bivalve mollusks using square wave anodic stripping voltammetry

An electrochemical sensor for the determination of Cu(II) in bivalve mollusks using a glassy carbon electrode modified with p-tert-butylcalix [4]arene-bis-cyrhetrenylimine (Cy2(Calix [4])) by square wave anodic stripping voltammetry (SWASV) has been developed. The organometallic compound was synthesized from cyrhetrene-carboxaldehyde and 25,26-bis-(2-aminoethoxy)-26,28-dihydrocalix [4]arene through a condensation reaction. Metalloligand (Cy2(Calix [4])) was characterized by FT-IR and 1H-13C 2D NMR spectroscopies and monocrystal X-ray diffraction and was obtained as a single isolated isomer (E). The optimum chemical and electrochemical conditions for the modified electrode were optimized and the methodology was applied in different samples of bivalve mollusks with satisfactory results. A cooperative effect between the organometallic fragment and the calixarene macrocycle improves the preconcentration capacity of the electrochemical sensor, creating a new opportunity to perform rapid and sensitive analyses in the detection of copper in marine resources.

Label-free electrochemical biosensors based on 3,3′,5,5′-tetramethylbenzidine responsive isoporous silica-micelle membrane

3,3′,5,5′-Tetramethylbenzidine (TMB) has been frequently used as an indicator in G-quadruplex/hemin DNAzyme (G4zyme)-based chemical and biochemical analysis, and its oxidation products are usually monitored by electrochemical or optical methods to quantify G4zyme formation-related analytes. Herein we report a simple electrochemical approach based on isoporous silica-micelle membrane (iSMM) to measure TMB, instead of its oxidation products, in G4zyme-based detection of specific analytes. The iSMM was grown on the indium tin oxide (ITO) electrode, which was composed of highly ordered, vertically oriented silica nanochannels and cylindrical micelles of cetyltrimethylammonium. The iSMM-ITO electrode was selectively responsive to neutral TMB but not its oxidation products, thanks to the sieving and pre-concentration capacity of micellar structures in terms of molecular charge and lipophilicity. In other words, only TMB could be extracted and enriched into micelles and subsequently oxidized at the underlying ITO electrode surface (namely the micelle/ITO interface), generating an amplified anodic current. Since the depletion of TMB was catalyzed by G4zymes formed in the presence of specific analyte, the decrease of this anodic current enabled the quantitative detection of this analyte. The current variation relative to its initial value ((j0−j)/j0), termed as the current attenuation ratio, showed the obvious dependence on the analyte concentration. As proof-of-concept experiments, four substances, i.e., potassium cation (K+), adenosine triphosphate, thrombin and nucleic acid, were detected in aqueous media and the analysis of K+ in pre-treated human serum was also performed.

Recent advances in the electrochemical detection of mercury

Electrochemical detection is one of the most important techniques for analysis of mercury. Electrodes with a high preconcentration capacity are employed to achieve a sensitive detection of mercury at concentrations harmless to health. The two most employed approaches in recent years are nanostructured electrodes and DNA-based assays. In the former case, electrodes with gold nanostructures, because their high affinity with mercury, and with carbon nanomaterials are the most reported. In the latter case, the strong bound between Hg(II) and thymine DNA bases allows the preconcentration of very small amounts of mercury. In this review, we critically evaluate the electrochemical detection of mercury reported in several works during the last few years.

Succinamic Acid Grafted Nanosilica for the Preconcentration of U(VI) from Aqueous Solution

Succinamic acid-functionalized nanosilica (SA@SiO2) was synthesized, characterized, and tested for hexavalent uranium preconcentration from contaminated aqueous solutions. The succinamic acid grafted nanosilica exhibited improved uranium preconcentration capacity in comparison with that of raw nanosilica. The effects of environmental conditions such as pH, ionic strength, solid concentration, foreign ions, and temperature on uranium(VI) preconcentration performance were investigated by batch technique in detail, and the related mechanism is discussed with the aid of X-ray photoelectron spectroscopy. Results showed that U(VI) preconcentration by SA@SiO2 was strongly dependent on pH while less dependent on ionic strength; the preconcentration was mainly dominated by inner-sphere surface complexation. The coexisting cations had no effects, while anions influenced U(VI) preconcentration significantly. The preconcentration of U(VI) was favorable at lower temperatures; the maximum preconcentration capacity was ...

Metal Oxide Assisted Preparation of Core-Shell Beads with Dense Metal-Organic Framework Coatings for the Enhanced Extraction of Organic Pollutants.

Dense and homogeneous metal-organic framework (MOF) coatings on functional bead surfaces are easily prepared by using intermediate sacrificial metal oxide coatings containing the metal precursor of the MOF. Polystyrene (PS) beads are coated with a ZnO layer to give ZnO@PS core-shell beads. The ZnO@PS beads are reactive in the presence of 2-methylimidazole to transform part of the ZnO coating into a porous zeolitic imidazolate framework-8 (ZIF-8) external shell positioned above the internal ZnO precursor shell. The obtained ZIF-8@ZnO@PS beads can be easily packed in column format for flow-through applications, such as the solid-phase extraction of trace priority-listed environmental pollutants. The prepared material shows an excellent permeance to flow when packed as a column to give high enrichment factors, facile regeneration, and excellent reusability for the extraction of the pollutant bisphenol A. It also shows an outstanding performance for the simultaneous enrichment of mixtures of endocrine disrupting chemicals (bisphenol A, 4-tert-octylphenol and 4-n-nonylphenol), facilitating their analysis when present at very low levels (<1 μg L(-1) ) in drinking waters. For the extraction of the pollutant bisphenol A, the prepared ZIF-8@ZnO@PS beads also show a superior extraction and preconcentration capacity to that of the PS beads used as precursors and the composite materials obtained by the direct growth of ZIF-8 on the surface of the PS beads in the absence of metal oxide intermediate coatings.

Whirling agitated single drop microextraction technique for the simultaneous analysis of Paraquat and Maneb in tissue samples of treated mice.

A new microextraction technique, whirling agitated single drop microextraction, has been proposed for the simultaneous analysis of Paraquat and Maneb in tissue samples before liquid chromatography with tandem mass spectrometry. This technique is based on the idea that the escalatory motion of the sample solution along with the extraction solvent increases the movement of molecules into the extraction solvent. In this technique, a simple handheld rotator was utilized to rapidly agitate the biphasic extraction system for the instantaneous extraction of targeted analytes. After extraction, the extracted phase was directly solidified by cooling in crushed ice and easily collected using a micro-spatula. The method showed good performance by achieving sensitive detection limits at 4.81 ng g(-1) (Paraquat) and 9.12 ng g(-1) (Maneb). Mean recoveries and enrichment factors were obtained >91.21% and up to 114 that ensured the preconcentration capacity of the method. The method precision was verified by evaluating intraday variation (n = 10) ≤4.57 (Paraquat) and ≤4.68 (Maneb) in terms of percent relative standard deviation. Additionally, method efficacy was assured by obtaining very little matrix interferences (≤3.11%). Moreover, the method suitability was also checked with its application on tissue samples of intraperitoneally treated mice with Paraquat and Maneb.

Growth and accelerated differentiation of mesenchymal stem cells on graphene oxide/poly-l-lysine composite films.

A new type of composite films of graphene oxide (GO) and poly-l-lysine (PLL) have been fabricated for use as bio-scaffold coatings with improved mechanical properties. The morphology, growth and differentiation of mesenchymal stem cells (MSCs) on the GO/PLL composite films have been examined. The results demonstrated that the GO/PLL composite films could not only support the growth of MSCs with a high proliferation rate, but could accelerate the osteogenic differentiation of MSCs, showing strong alkaline phosphatase (ALP) and gene expression. Importantly, the high pre-concentration capacity of the GO/PLL films for osteogenic inducers could play a key role in accelerating the osteogenic differentiation of MSCs through the strong non-covalent binding and electrostatic interaction between them. Moreover, the mild and inexpensive fabrication strategy could be applicable to biomacromolecules including chitosan, gelatin, etc. Therefore, such a kind of composite film could provide a multifunctional and highly biocompatible scaffold coating tailored for potential application in stem cell research.

Stir bar sorptive extraction polar coatings for the determination of chlorophenols and chloroanisoles in wines using gas chromatography and mass spectrometry

The simultaneous determination of 14 chlorophenols (CPs) and chloroanisoles (CAs) in wine samples is carried out using stir bar sorptive extraction (SBSE) with thermal desorption and gas chromatography-mass spectrometry (TD-GC-MS), evaluating the preconcentration efficiency of two different polar extracting phases, ethylene glycol-silicone (EG-Silicone) copolymer and polyacrylate, which have recently become commercially marketed. The influence of several extraction variables on the preconcentration capacity of these two novel coatings was tested, as well as the variables affecting the thermal desorption step. The EG-Silicone extraction phase provided the best results, since it allowed the simultaneous preconcentration of both species the non-polar CAs, due to the silicone base, and the polar CPs, because of the ethylene glycol polymer. Consequently, under the finally selected conditions, CPs were determined without any derivatization step, reaching detection limits in the 0.3-1.4 ng L(-1) range, depending on the compound. For CAs the detection limits ranged from 0.2 to 0.5 ng L(-1), with good precision and recovery. Five CAs and three CPs were found in several analyzed wines, some of which can be regarded as defective considering their contents in 2,4,6-TCA and 2,6-DCA.

Simultaneous detection of antibacterial sulfonamides in a microfluidic device with amperometry

A highly sensitive and robust method for simultaneous detection of five sulfonamide drugs is developed by integrating the preconcentration and separation steps in a microfluidic device. An ampetrometry is performed for the selective detection of sulfonamides using an aluminum oxide–gold nanoparticle (Al2O3–AuNPs) modified carbon paste (CP) electrode at the end of separation channel. The preconcentration capacity of the channel is enhanced by using the field amplified sample stacking and the field amplified sample injection techniques. The experimental parameters affecting the analytical performances, such as pH, % of Al2O3, volume of AuNPs, buffer concentration, and water plug length are optimized. A reproducible response is observed during the multiple injections of samples with RSDs<4%. The calibration plots are linear with the correlation coefficient between 0.991 and 0.997 over the range between 0.01 and 2025pM. The detection limits of five drugs are determined to be between 0.91 (±0.03) and 2.21 (±0.09)fM. The interference effects of common biological compounds are also investigated and the applicability of the method to the direct analysis of sulfonamides in real meat samples is successfully demonstrated. Long term stability of the modified electrode was also investigated.

Separation and simultaneous detection of anticancer drugs in a microfluidic device with an amperometric biosensor

A simple and highly sensitive method for simultaneous detection of anticancer drugs is developed by integrating the preconcentration and separation steps in a microfluidic device with an amperometric biosensor. An amperometric detection with dsDNA and cardiolipin modified screen printed electrodes are used for the detection of anticancer drugs at the end of separation channel. The preconcentration capacity is enhanced thoroughly using field amplified sample stacking and field amplified sample injection techniques. The experimental parameters affecting the analytical performances, such as pH, temperature, buffer concentration, water plug length, and detection potential are optimized. A reproducible response is observed during multiple injections of samples with a RSD <5%. The calibration plots are linear with the correlation coefficient between 0.9913 and 0.9982 over the range of 2–60 pM. The detection limits of four drugs are determined to be between 1.2 (±0.05) and 5.5 (±0.3) fM. The applicability of the device to the direct analysis of anticancer drugs is successfully demonstrated in a real spiked urine sample. Device was also examined for interference effect of common chemicals present in real samples.

Extraction and preconcentration capacity of bifunctionalized diamine-thiol polysiloxane immobilized ligand system towards some divalent cations

Porous solid bi-organofunctionalized diamine-thiol polysiloxane immobilized ligand system of the general formula P-(CH2)3- X, (where P represents [Si-O]n siloxane network and X represents a mixture of diamine; -NH(CH)2NH2 and thiol; -SH functional groups) has been prepared by hydrolytic polycondensation of TEOS with a mixture of 3-mercaptopropyltrimethoxysilane and 3- (2-aminoethylimino)propyltrimethoxysilane agents. The ligand system was evaluated for extraction and preconcentartion of a series of divalent metal ions from aqueous solutions including: Co2+, Ni2+, Cu2+, Zn2+, Cd2+ and Pb2+. Both batch and dynamic methods were used to examine maximum sorption capacity. The maximum binding capacity followed the sequence; Cu2+ > Pb2+ > Cd2+ > Ni2+ > Zn2+ > Co2+ at pH 5.5. Measurement of variation of sorption of metal ions with temperature yielded negative values of ΔG° and positive values of ΔS° and ΔH° indicating a spontaneous and endothermic process of binding metal ions to the ligand system.

Adsorption of heavy metals by pirymidine-derivated mesoporous hybrid material

This paper describes the synthesis of pyrimidine-derivated hybrid mesoporous material via chemical bonding. This has been done by modifying the silanol groups of the support with a synthesised pyrimidine propyl triethoxysilane. The hybrid material has been characterized by X-ray diffraction, nitrogen adsorption techniques, FT-IR, 29Si and 13C MAS NMR. The potential of the material of removing heavy metal as copper, nickel and cobalt from water has been tested. Effects of pH, velocity of adsorption, selectivity, maximum adsorption capacity and preconcentration capacity have been determined.