Solid Phase Preconcentration Research Articles

An overview of preconcentration techniques combined with inductively coupled plasma mass spectrometry for trace element determination in biological studies.

In the last decades, the determination of trace elements in biological materials has emerged as an important area of study because of its relevance to human health and the environment. Inductively coupled plasma mass spectrometry (ICP-MS) has proven to be a powerful tool for trace element analysis, owing to its high sensitivity and ability to determine several elements in a single measurement. However, given the complex nature of biological matrices and the presence of elements, most of them at ultratrace levels, it becomes crucial to complement ICP-MS with preconcentration techniques to increase the sensitivity and selectivity of analytical methods. This article presents an exhaustive overview of liquid- and solid-phase preconcentration techniques used in combination with ICP-MS for trace element determination in different biological samples from 2000 to the present. An in-depth discussion of the advances on the application of state-of-the-art solvents and materials in trace element extraction and preconcentration is presented. Special attention is given to different strategies for elemental speciation analysis, employing both chromatographic and non-chromatographic techniques. The role of automation in these methodologies is also described. Finally, future trends and challenges related to this topic are discussed.

Synthesis and performance of cross-linked poly(vinylpyridine-co-protoporphyrin) for effective cobalt determination using a micro-packed column hyphenated system coupled to FAAS

The present study describes the development of a solid phase preconcentration method for cobalt determination at trace levels using cross-linked poly(vinylpyridine-co-protoporphyrin) as a highly efficient adsorbent and a hyphenated flow injection-FAAS system. The influence of molar amount of protoporphyrin and 4-vinylpyridine in the copolymer was studied aiming at obtaining the optimum synthesis condition in terms of adsorption capacity and swelling effect. The polymers were characterized by FT-IR, SEM, nitrogen adsorption/desorption, and swelling analyses. The method is based on cobalt preconcentration at pH 9.0 in 0.01 mol L−1 Tris/Tris-HCl buffer through the cylindrical mini-column packed with 50 mg of adsorbent at a flow rate of 7.4 mL min−1, whilst the elution was carried out by using 2.0 mol L−1 HNO3. Using the best synthesis conditions, the solid phase preconcentration method using poly(vinylpyridine-co-protoporphyrin) named poly(4VP-PP) (5.00 mmol of 4-vinylpyridine and 0.10 mmol of protoporphyrin) provided a linear range from 4.60–200.0 μg L−1, the limit of detection of 1.38 μg L−1, preconcentration factor of 38, consumption of index of 0.53 mL and analytical frequency of 22 h−1. Using the poly(4VP-PP), the method showed high selectivity for cobalt determination in the presence of concomitant ions, when compared to poly(4VP), thereby indicanting the great importance of protoporphyrin on the selective analytical performance of the method. The poly(4VP-PP) was successfully applied for the preconcentration of cobalt from different kind of samples without matrix interference, including dark chocolate powder, black tea, infusion of black tea, and water samples (mineral, tap, and lake waters), with high recovery results (91–104%). The feasibility of the method was also attested by analysis of certified reference material of marine sediment (MESS-3).

Pre-concentration and extraction of fenitrothion using a prefabricated 3D spongin-based skeleton of marine demosponge: optimization by experimental design

A new approach for solid phase extraction (SPE) and preconcentration of aqueous fenitrothion (FNT) specimens was developed with the aid of a natural renewable biomaterial (spongin) as a sorbent. The SPE was performed prior to HPLC–UV-DAD analysis of the analyte. The effects of different factors including pH value, amount of sorbent, eluent type and its volume, adsorption time and salt effect on the efficiency of the developed SPE process were optimized through experimental design. It was observed that the optimal conditions lead to a linear dynamic range of 5–500 ng mL−1, as well as limits of detection (LOD) and quantification (LOQ) as low as 1.3 ng mL−1 and 4.3 ng mL−1, respectively. The relative standard deviation (RSD%, n = 5) was 2.7% at a concentration 10 ng mL˗1 of fenitrothion. The spongin as a green adsorbent in the developed approach was effectively used for the first time in extraction the fenitrothion from various real samples.

Immunomagnetic Separation of Salmonella with Tailored Magnetic Micro- and Nanocarriers.

One of the main drawbacks in current methods for bacterium detection is their quantification at very low concentration level in complex specimens. Novel developments that are needed involve solid-phase preconcentration procedures which can be easily integrated with emerging technologies. Here, we describe the immunomagnetic separation (IMS) of Salmonella using magnetic carriers. Nano (300nm) and micro (2.8μm) sized magnetic particles are modified with anti-Salmonella antibody to preconcentrate the bacteria from the samples throughout an immunological reaction. The immunomagnetic separation can be easily coupled with downstream characterization and quantification methods, including classical culturing, molecular biology techniques such as PCR, immunoassays, confocal and scanning electron microscopy, and emerging technologies and rapid detection methods including biosensors, lateral flow, and microfluidic devices.

Magnetic solid phase preconcentration of cadmium in water samples using sulfonic acid functionalized Kit-6 magnetite mesoporous nanocomposites followed by flame atomic absorption spectrometry

In this study, a simple and sensitive extraction method has been developed for preconcentration of trace amounts of cadmium ions using Kit-6 magnetite mesoporous nanocomposites (MMNCs) functionalized with sulfonic acid groups as adsorbent in solid phase extraction followed by flame atomic absorption spectrometry. For this purpose, the Kit-6 mesoporous silica was chemically synthesized on the surface of silica-coated magnetite core and functionalized by sulfonic acid groups to obtain Fe3O4@SiO2@Kit-6-SO3H. The synthesized nanocomposites were characterized by XRD, SEM, VSM and EDX methods. Various parameters affecting adsorption/desorption efficiencies were investigated using Taguchi orthogonal array design. The maximum extraction efficiency of cadmium ions was obtained at pH = 8, sorbent weight = 0.1 g, ionic strength = 0, stirring time = 15 min, sample volume = 100 mL, time of desorption = 5 min, concentration and volume of HCl solution as desorption solvent 0.1 M and 3 mL, respectively. The linear dynamic range, limit of detection, enhancement factor and relative standard deviation (RSD %) of the proposed method were obtained as 0.5–100 µg L−1 (R2 = 0.9982), 0.4 µg L−1, 26.9 and 3.5%, respectively. Finally, the study of proposed MMNC adsorbent for real sample and investigating the interference potential of foreign ions successfully confirmed the ability of MMNCs for preconcentration and determination of trace levels of cadmium ions.

Simultaneous Preconcentration and Determination of Rhodamine B and Brilliant Blue

A simultaneous solid-phase preconcentration and spectrophotometric determination method based on adsorption of rhodamine B (RB) and Brilliant Blue FCF (BB) synthetic dyes onto Chromosorb 108 resin was developed. Solution pH, sample, eluent flow rates and eluent type were optimized. RB and BB concentrations were determined at 556 and 630 nm, respectively. Matrix effects of interference components were examined. Preconcentration factors and detection limits of the dyes were calculated. Adsorption isotherms of method, surface micrographs and pHzpc of resin experiments were performed. Limit of detections of the method were determined 0.22 and 0.31 µg L−1 for RB and BB, respectively. The method was successfully applied to determine RB and BB in industrial, foodstuff, cosmetics and environmental water samples. RB contents were found between 2.11 and 5.89 µg mL−1 for liquid samples and 17.55 and 370 µg g−1 for solid samples. BB concentrations in investigated solid samples were between 3.00 and 53.38 µg g−1. BB contents of liquid samples were determined between 1.57 and 9.66 µg mL−1. In order to test applicability of the method, analyte addition/recovery technique was also used. Quantitative recovery values ranging from 95 to 103% were obtained from the analyte addition/recovery tests.

Magnetic iron oxide nanoparticles for HPLC determination of valsartan in aqueous environmental samples, biological samples and tablet dosage forms

ABSTRACT Magnetic iron oxide nanoparticles (MIONPs) were newly synthesised and then modified by cetyltrimethylammonium bromide (CTAB) for solid phase extraction, preconcentration and determination of valsartan (VAL) followed by high performance liquid chromatographic analysis. The synthesised magnetic Fe3O4 nanoparticles were used as adsorbent and methanol was used as desorbing solvent. The separation was performed using a RP-C18 BDS hypersil chromatographic column and an isocratic mobile phase consisting of phosphate buffer (0.03 M):acetonitrile:methanol (40:40:20%). A diode array detector at wave length 210 nm was used. Chromatographic analysis time was less than 5 minutes per sample with complete resolution of VAL from the different studied matrices components (tR of VAL = 4.20 minutes). Important parameters such as adsorbent and CTAB volume, extraction time and desorption solvent type and time were optimised. A good linear response was obtained in the concentration range of 10–150 ng/mL with determination coefficient (r 2) of 0.9998. Limits of detection and quantification were found to be 2.02 and 6.72 ng/mL. The proposed method was applied successfully for determination of VAL in raw material, aqueous environmental samples, biological samples, tablet dosage forms with good recovery values indicating high accuracy of the method.

Immobilization of unmodified aminoanthraquinone derivatives onto silica gel surface for solid-phase extraction and pre-concentration of Pb(II)

ABSTRACT In this project, silica gel chemically bonded with derivatives of aminoanthraquinone were synthesized and characterized. Adsorbents 1,8-aminoanthraquinone-3-aminopropylsilica (SL1), 2-aminoanthraquinone-3-aminopropylsilica (SL2) and 1-aminoanthraquinone-3-aminopropylsilica (SL3) were produced and tested to adsorb heavy metal solutions including Pb(II) Cu(II) Zn(II) Cd(II) and Co(II). The concentrations of the adsorbed heavy metals solution were calculated by atomic adsorption spectrophotometry employing a batch method. The results showed that speed at 200 rpm for 30 min with pH 9 is the optimum condition for heavy metal adsorption. The result also indicated that adsorbent SL3 is the best adsorbent for Pb(II) at 82.5%, and the relative standard deviation (R.S.D.) was lower than 6%. The method detection limit was 1.1 µg L−1 for Pb2+. In addition, Density Functional Theory (DFT) calculation results suggested that the adsorbent sensor formed stable complexes with Pb(II) through a large number of cation-dipole interactions. The method was also applied with satisfactory results to the pre-concentration of trace Pb(II) in environmental samples.

Adsorption isotherm and kinetic modeling of a novel procedure for physical modification of silica gel using aqueous solutions of 4,4′-(1,2-ethanediyldinitrilo)bis-(2-pentanone) for preconcentration of Ni(II) ion

ABSTRACT Aqueous solutions of 4,4′-(1,2-ethanediyldinitrilo)bis-(2-pentanone) (EDDBP) have been used in a novel green procedure for the physical modification of silica gel (SG) for solid-phase extraction and preconcentration of Ni(II) ion. Optimization experiments were carried out at 301 ± 1 K by batch technique. The EDDBP-modified SG was characterized using X-ray Diffraction Spectroscopy (XRD) and Brunaeur-Emmett-Teller (BET) determinations. The adsorption isotherm and kinetic models indicated a physisorption process. The modified SG showed moderate to high adsorption capacity values for Ni(II) ion (~98% removal efficiency) at pH 8. A sorption mechanism for Ni(II) chelation with EDDBP-modified-SG was proposed. These results suggest the procedure has advantages.

Application of selective solid-phase extraction using a new core-shell-shell magnetic ion-imprinted polymer for the analysis of ultra-trace mercury in serum of gallstone patients

ABSTRACT A new ultrasonically assisted spectrophotometric method was developed using stabilized ion polymer on a modified nano-absorbent as a core- shell-shell absorbent (Fe3O4@SiO2@TiO2–IIP). It has the advantages of further stabilizing the polymer and consequently and much higher efficiency than its conventional adsorbents. The prepared sorbent was characterized and Its parameters were investigated by a Box–Behnken design. The linear dynamic range and limit of detection were 0.20–28.00 µg L−1 and 0.05 µg L−1 respectively. In selectivity study, it was founded that imprinting causes increased affinity of the prepared IIP toward Hg2+ ion. The proposed IIP is considered to be promising and selective sorbent for solid-phase extraction and preconcentration of Hg2+ ion in sera of different types of gallstone patients.

Solid phase extraction and preconcentration of some metal ions using Schiff base immobilised silica gel followed by ICP-OES

ABSTRACTIn this study, a simple and efficient solid phase extraction procedure was developed for simultaneous separation and preconcentration of Ba, Cd, Co, Cu, Mn and Ni. The methodology was based on preconcentration of the target analytes on N,N’-bis(4-methoxysalicylidene)-1,3-propanediamine modified silica gel prior to inductively coupled plasma optic emission spectrometry detection. The experimental conditions were as follows: pH of sample 5.00; sample and eluent flow rates 3 mL min−1; sample volume 25 mL; eluent 0.5 mol L−1 HNO3; eluent volume 3.0 mL. Preconcentration factor was achieved as 33.3 for Ba, Co, Mn; 83.3 for Cd, Ni; 166.7 for Cu. Limits of detection were found as 0.33, 0.26, 0.27, 0.36, 0.27 and 0.19 µg L−1 for Ba, Cd, Co, Cu, Mn and Ni, respectively. The relative standard deviations of 2.6–3.8% were obtained via nine parallel analyses. The suggested procedure was successfully validated by the analysis of TMDA-53.3 Lake Ontario water and ERM-CA022a soft drinking water certified reference materials and applied to various natural water samples.

Performance of restricted access copper-imprinted poly(allylthiourea) in an on-line preconcentration and sample clean-up FIA-FAAS system for copper determination in milk samples

A new on-line solid phase preconcentration method using an ion-imprinted polymer with restrict access material based on copper-imprinted poly(allylthiourea) modified with 2-hydroxyethyl methacrylate and bovine serum (IIP-HEMA-BSA) to preconcentrate Cu2+ ions and exclude protein from milk samples via FIA-FAAS was developed. The samples were on-line preconcentrated at pH 4.5 through a mini-column packed with 50.0 mg of IIP-HEMA-BSA at a flow rate of 7.6 mL min−1 followed by a counter-current elution with 1.00 mol L−1 HCl towards the FAAS detector. The interference of ions commonly found in milk samples and the presence of BSA were investigated in the Cu2+ ions preconcentration. The method provided an analytical curve ranging from 3.6 to 100.0 μg L−1, preconcentration factor of 24-fold, limit of detection of 1.1 μg L−1 and sample throughput of 20 h−1. The accuracy of the method was attested by Cu2+ ions addition/recovery tests as well as by using GFAAS of samples microwave-assisted digested. The proposed method was successfully applied to the copper determination in milk samples, requiring only pH adjustment followed by preconcentration step as sample pretreatment. Copper content in bovine milk sample was 0.635 ± 0.042 mg kg−1, while to soybean milk samples were between 0.048 ± 0.008 and 0.094 ± 0.005 mg kg−1. To the best of our knowledge, the potential of IIP-HEMA-BSA for Cu2+ ions extraction from biological samples and simultaneous removal of macromolecules employing minimal sample pretreatment was demonstrated for the first time. The proposed extraction method stands out by being simple, fast and a low-cost analytical strategy when compared to the conventional microwave-assisted acid digestion.

Selective solid phase extraction and preconcentration of ultra-trace inorganic mercury in water samples using 2,6-dimethyl-morpholine dithiocarbamate

ABSTRACTA sensitive and selective solid-phase spectrophotometric method for the determination of trace amounts of Hg(II) cation in water is described. A complex was created with Hg(II) using 2,6-dimethyl-morpholine dithiocarbamate (DMMDTC) to form Hg(II)–(DMMDTC) and this complex was adsorbed onto microcrystalline naphthalene (MN) and then eluted with 5% acetic acid (in ethanol) solution. A preconcentration factor of 187 and a recovery of 95% were observed at pH of 5.0 and for 10 min. of extraction. The separated Hg(II) ions were quantified by using ultraviolet-visible spectrophotometer at 490.0 nm by creating a colored complex with dithizone in Triton X-100 surfactant media. Molar absorptivity and sandell’s sensitivity for the Hg(II)-dithizone were determined as 4.96 × 105 Lmol−1cm−1 and 0.4032 µg cm−2, respectively. The detection limit (LOD) was 1.7 μg L−1 under the optimized conditions of the analytical method.

Characterization of Disinfection By-Products in Arkhangelsk Tap Water by Liquid Chromatography/High-Resolution Mass Spectrometry

Disinfection of drinking water with chlorine-containing reagents leads to the formation of a large number of disinfection by-products, resulting from the chlorination of natural dissolved organic matter. High-performance liquid chromatography/high-resolution mass spectrometry with solid-phase preconcentration on a polymeric sorbent was used to study the component composition of halogen-containing disinfection by-products in Arkhangelsk tap water. Fourteen chlorinated and brominated organic compounds, which belong to the classes of halophenols, aromatic acids, carbonyl compounds, and chlorine-substituted nitrogen-containing heterocyclic compounds, have been found. Based on the analysis of MS/MS spectral data, possible structures of the detected disinfection by-products are proposed.

Screening of drugs and homeopathic products from Atropa belladonna seed extracts: Tropane alkaloids determination and untargeted analysis

Homeopathic products are still a controversial issue in modern medicine, understood as complementary or alternative medicine (CAM). In this particular case, homeopathic products prepared from Atropa belladonna extracts may present specific problems due to the effects derived from its components. This article applies a simple, rapid, reliable method to the analysis of different homeopathic products obtained from Atropa belladonna; drugs containing high concentration of plant extracts; and Atropa belladonna seeds. The method was based on a simple solid-phase preconcentration method followed by ultra-high pressure liquid chromatography (UHPLC) coupled to high resolution mass spectrometry using Exactive-Orbitrap as an analyser. An in-house database was set and atropine and scopolamine were the compounds detected at highest concentrations in homeopathic products from Atropa belladonna extracts (4.57 and 2.56μg/kg, respectively), in Belladonna ointment (4007 and 1139μg/kg, respectively) and Belladonna seeds (338 and 32.1mg/kg, respectively). Other tropane alkaloids such as tropine, apoatropine, aposcopolamine, tropinone, homatropine, and anisodamine were detected at lower concentrations (0.04-1.36μg/kg). When untargeted analysis was performed, other tropane alkaloids were identified in the tested samples, such as ecgonine (0.003μg/kg), benzoylecgonine (0.56μg/kg), calystegines A (19.6μg/kg), B (33.1μg/kg), and C (1.01μg/kg). Finally other compounds present in the homeopathic products, such as sugars (fructose, glucose, and lactose) or amino acids (valine, ornithine, leucine, and phenylalanine), were identified.

Determination of trace elements in samples with high salt content by inductively coupled plasma mass spectrometry after solid-phase preconcentration

A method for solid-phase extraction (SPE) using nanometer-sized silica modified with N-[2-aminoethyl]-3-aminopropyltrimethoxysilane (AAPTS) coupled with inductively coupled plasma mass spectrometry (ICP-MS) was proposed in this work for analysis of Ni(II), Cu(II), Ga(III), Cd(II), Pb(II), and Bi(III). It was noted from zeta potentials that the absorptivity of the modified nanoparticles could be partially attributed to the electrostatic interactions of amino groups in alkaline conditions. Elemental ions were adsorbed at a pH of 9.0 and then eluted with 1 mol/L nitric acid and 0.5% citric acid. Effects of enrichment time, sample flow rate, and coexisting ions were also investigated. Using the same instrument conditions, higher recovery of elements in synthetic seawater after solid-phase extraction was achieved compared to directly diluting 50 times with 1% nitric acid. This method was successfully applied for the determination of trace metal ions (Ni, Cu, Ga, Cd, Pb, and Bi) in milk powder samples.

Solid Phase Extraction and Flame Atomic Absorption Determination of Cadmium in Water Samples

A new sensitive and selective method including solid phase preconcentration and next determination of trace amounts of Cd(II) by flame atomic absorption spectroscopy in water samples was developed. Cadion was coated on carbon active powder and used as a solid phase sorbent. Detection limit for extraction of 2000 mL aqueous solution is 0.35 μg·L–1. The relative standard deviations for concentrations 2.5 and 15 μg·L–1 with preconcentration factor 200, 0.4 and 0.2% (n = 3) were obtained, respectively. The calibration curve is linear in the range of 1.5–15 μg·L–1. The accuracy of the method was evaluated and confirmed by the inductively coupled plasma atomic emission spectrometric analysis. Method was applied for the determination of cadmium in well water.

Sequential synthesis of a magnetic nano-adsorbent: How the first step identifies the final product

Three types of super paramagnetic core-shell nanoparticles have creatively been synthesized via three basic substances, Fe2+/Fe3+, methacrylic acid (MAA), and 2,2′-azobisisobutyronitrile (AIBN). It has been demonstrated that the order of addition of starting materials determines the type of products. Methacrylic acid coated magnetic nanoparticles (Fe3O4@MAA) with abundant double bonds on the surface, poly methacrylic acid coated magnetic nano particles (Fe3O4@PMAA) having plenty of surface carboxylic groups, and amphiphilic shell of methacrylic acid polymer on magnetic nano particles core (Fe3O4@AMPH) having both carboxyl and alkyl groups on the surface were prepared in three, separate one-pot, sequential synthesis. At first, the resultant magnetic nanoparticles (MNPs) were characterized by transmission electron microscopy (TEM), dynamic light scattering, X-ray spectroscopy, Fourier transform infrared spectroscopy (FTIR) and thermal analysis. Then, the colloidal stability of the synthesized particles was investigated in several common solvents such as water, 1-propanol, chloroform, and edible oil. Finally, the application of each nanoparticle was discussed. It was found that Fe3O4@MAA can be successfully applied as a core in polymerization procedure. Fe3O4@PMAA performed well in nickel uptake and can therefore be used as magnetic solid sorbent in nickel pre-concentration and remediation. Fe3O4@AMPH was well dispersed in oil, suggesting that it can be successfully used as a good extractor in dispersive solid phase pre-concentration and cleanup of both hydrophilic and hydrophobic compounds in heated edible oil samples.

Liquid electrode plasma-optical emission spectrometry combined with solid-phase preconcentration for on-site analysis of lead.

A relatively rapid and precise method is presented for the determination of lead in aqueous matrix. The method consists of analyte quantitation using the liquid electrode plasma-optical emission spectrometry (LEP-OES) coupled with selective separation/preconcentration by solid-phase extraction (SPE). The impact of operating variables on the retention of lead in SPEs such as pH, flow rate of the sample solution; type, volume, flow rate of the eluent; and matrix effects were investigated. Selective SPE-separation/preconcentration minimized the interfering effect due to manganese in solution and limitations in lead-detection in low-concentration samples by LEP-OES. The LEP-OES operating parameters such as the electrical conductivity of sample solution; applied voltage; on-time, off-time, pulse count for applied voltage; number of measurements; and matrix effects have also been optimized to obtain a distinct peak for the lead at λmax=405.8nm. The limit of detection (3σ) and the limit of quantification (10σ) for lead determination using the technique were found as 1.9 and 6.5ng mL-1, respectively. The precision, as relative standard deviation, was lower than 5% at 0.1μg mL-1 Pb, and the preconcentration factor was found to be 187. The proposed method was applied to the analysis of lead contents in the natural aqueous matrix (recovery rate:>95%). The method accuracy was verified using certified reference material of wastewaters: SPS-WW1 and ERM-CA713. The results from LEP-OES were in good agreement with inductively coupled plasma optical emission spectrometry measurements of the same samples. The application of the method is rapid (≤5min, without preconcentration) with a reliable detection limit at trace levels.

Synthesis of Chelating Agent Free-Solid Phase Extractor (CAF-SPE) Based on New SiO2/Al2O3/SnO2 Ternary Oxide and Application for Online Preconcentration of Pb2+ Coupled with FAAS

A new online solid phase preconcentration method using the new SiO2/Al2O3/SnO2 ternary oxide (designated as SiAlSn) as chelating agent free-solid phase extractor (CAF-SPE) coupled to flame atomic absorption spectrometry (FAAS) for Pb2+ determination at trace levels in different kind of samples is proposed. The solid adsorbent has been characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron miscroscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray fluorescence spectroscopy (XRF) and textural data. The method involves the preconcentration using time-based sampling of Pb2+ solution at pH 4.3 through 100.0 mg of packed adsorbed into a mini-column under flow rate of 4.0 mL min-1 during 5 min. The elution step was accomplished by using 1.0 mol L-1 HCl. A wide range of analytical curve (5.0-400.0 µg L-1), high enrichment factor (40.5), low consumption index (0.5 mL) and low limits of quantification and detection, 5.0 and 1.5 µg L-1, respectively, were obtained with the developed method. Practical application of method was tested on water samples, chocolate powder, Ginkgo biloba and sediment (certified reference material). On the basis of the results, the SiAlSn can be considered an effective adsorbent belonging to the class of CAF-SPE for Pb2+ determination from different matrices.