Mg Of Sorbent Research Articles

Dispersive solid-phase microextraction with arginine-functionalized magnetic nanocomposite as the sorbent for separation and preconcentration of aspartame and optimization using response surface methodology

In this study, the surface of magnetic dialdehyde starch nanocomposite has been modified with arginine amino acid (Arg) and employed as an adsorbent for the enrichment of aspartame (ASP) in different real samples. Magnetite dispersive solid-phase microextraction (MDSPME), which had been combined with spectrophotometry, has been used to determine the extracted aspartame. The Plackett–Burman design has been employed to investigate the influence of main parameters including the amount of salt, sample volume, amount of sorbent, dispersive solution volume, desorption, and extraction time, and central composite design has been used to obtain the optimum condition in MDSPME method. Under optimum conditions, 15 ml of sample volume, 1.5 ml of ethanol as dispersive solvent, 10 min of extraction time, 15 min of desorption time, 10 mg of sorbent, and 0 w/v % of salt, the calibration graph has been observed to be linear in a concentration range of 2–15 µg ml−1, while the limit of detection has been 0.064 µg ml−1. The relative standard deviations of 3.64 and 4.12 have been obtained at 8 µg ml−1 level of aspartame for the intra- and inter-day analysis. In addition, the enrichment factor has been about 128. This procedure has been successfully utilized for distinguishing the existing aspartame in two kinds of beverage that had been procured from local markets and drinkable water.

Extraction of Phthalic Acid Esters and Di(2-ethylhexyl) Adipate from Tap and Waste Water Samples Using Chromabond® HLB as Sorbent Prior to Gas Chromatography-Mass Spectrometry Analysis

In this work, Chromabond® HLB was evaluated as an extraction sorbent of a group of seven phthalic acid esters (PAEs; i.e., dipropyl phthalate, DPP, dibutyl phthalate, DBP, diisopentyl phthalate, DIPP, di-n-pentyl phthalate, DNPP, butylbenzyl phthalate, BBP, dicyclohexyl phthalate, DCHP, and di(2-ethylhexyl)phthalate, DEHP) and one adipate (di(2-ethylhexyl) adipate, DEHA) from tap and waste water prior to gas chromatography-mass spectrometry. After the optimization of the extraction conditions (200 mg of sorbent conditioned with 10 mL of acetonitrile and 2 mL of Milli-Q water, extraction of 50 mL of water at pH 6.0, vacuum drying for 20 min and elution with 10 mL of ethyl acetate), a recovery study was developed at different concentration levels in each matrix, which revealed that most of the target analytes could be recovered between 75 and 112%, with relative standard deviation values for all of them below 20%. Matrix effect was evaluated, finding that matrix-matched calibration should be developed for most analytes in both matrices. The limits of quantification (LOQs) of the method were in the 0.82–71 ng L−1 range. The developed method was also applied to the extraction of the target PAEs in different water samples finding some of them, in particular, DNPP in tap water samples, and BBP and DCHP in waste water, but below the LOQs of the method.

The Extraction and determination of benzene from waters and wastewater samples based on functionalized carbon nanotubes by static head space gas chromatography mass spectrometry

In this study, the phenyl sulfonic acid (PhSA) modified carbon nanotubes (CNTs) were used for benzene removal from waters by (D- μSPE). Due to adsorption mechanism, π–π interactions was provided between the aromatic ring of benzene with the surface (SO3H) and phenyl ring (-C6H5) of CNTs, respectively. Therefore, 20-100 mg of sorbent, concentration of benzene (0.1–10 mg L-1), pH (1-12) and contact time (5–120 min) were investigated and optimized for benzene removal from water samples in static system. The concentration of benzene in water was determined by (SHS-GC-MS). The results showed, the Langmuir-Freundlich (LF) isotherm provided the best fit for benzene sorption. By using the Langmuir model, the maximum adsorption capacity of 117.34 and 22.86 mg/g was achieved for benzene removal from waters with CNTs@PhSA and CNTs, respectively. Under optimal conditions, adsorption efficiency of CNTs@PhSA and CNTs was obtained 97.7% and 20.6 % for benzene removal from water samples, respectively.

A mesoporous nanosorbent composed of silica, graphene, and palladium (II) for ultrasound-assisted dispersive solid-phase extraction of organophosphorus pesticides prior to their quantitation by ion mobility spectrometry.

A new ultrasonic-assisted dispersive solid-phase extraction method using mesoporous nanosorbent composed of silica, graphene, and palladium (II) (M S/G@-SH@Pd (II)), coupled with corona discharge ion mobility spectrometry, was developed for trace determination of organophosphorus pesticides. Initially, the M S/G@-SH@Pd (II) nanosorbent was synthesized and characterized. Then, the nanosorbent was used for the sorption and extraction of organophosphorus pesticides. Under the optimized conditions (pH = 7.0, 15 mgof sorbent, 3 minextraction time, ethanol asdesorption agent, 3 mincentrifuge time), the proposed technique provided good linearity (R2 > 0.994), repeatability (RSD < 4.6%), low limits of detection (0.15-0.30ngmL-1), excellent preconcentration factor (PF = 472-478), and high recoveries (93-94%). Themethod was applied tothe determination of organophosphorus pesticides in real water samples. The sorbent was reused in 5 cycles without any considerable loss of activity. Graphical abstract Schematic presentation of design and synthesis of mesoporous nanosorbent composed of silica, graphene, and palladium (II) for ultrasound-assisted dispersive solid-phase extraction of organophosphorus pesticides prior to their quantitation by ion mobility spectrometry.

Poly(N-acryloyl-glucosamine-co-methylenebisacrylamide)-based hydrophilic magnetic nanoparticles for the extraction of aminoglycosides in meat samples

Poly(N-acryloyl-glucosamine-co-methylenebisacrylamide) (poly(AGA-co-MBA))-modified Fe3O4 nanoparticles were prepared via simple aqueous surface polymerization. The resultant Fe3O4@poly(AGA-co-MBA) nanoparticles were used as hydrophilic magnetic solid phase extraction sorbents. Ten aminoglycosides were selected as model analytes to evaluate the extraction performance and mechanism of the sorbents. The prepared magnetic nanoparticles were characterized by Fourier transformed infrared spectroscopy, elemental analysis, a vibrating sample magnetometer, and so on. The sorbents exhibited efficient extraction towards model analytes in hydrophilic interaction chromatography. Only 10.0 mg of sorbent was needed to adsorb analytes from 10.0 mL of a sample solution within a short time (5.0 min). Under optimized conditions, Fe3O4@poly(AGA-co-MBA) nanoparticles were applied in the sample preparation for the analysis of 10 aminoglycosides in meat samples by high-performance liquid chromatography-tandem mass spectrometry. The limits of detection (LODs) for the 10 aminoglycosides were in the range of 0.6–23.6 µg kg−1. Satisfactory recoveries of spiked meat samples from 84.6–98.3% with acceptable relative standard deviations from 3.1% to 7.8% were achieved. Compared to other reported methods for the analysis of aminoglycosides, the present work had comparable or higher sensitivities with a simple extraction procedure. The proposed hydrophilic interaction extraction sorbents are promising as powerful alternatives for extracting and enriching aminoglycosides in animal-derived food samples.

Construction of molecularly imprinted nanoparticles by employing ultrasound waves for selective determination of doxepin from human plasma samples: Modeling and optimization.

In this work, molecularly imprinted nanoparticles (MINPs) were applied as selective adsorbent for ultrasound-assisted micro-solid-phase extraction (UAMSPE) of doxepin (DP) from human plasma samples, which was then cleaned up, pre-concentrated and subjected to HPLC. The MINPs were synthesized based on a non-covalent approach by precipitation polymerization utilizing methacrylic acid and styrene as functional monomers, DP as template, ethylene glycol dimethacrylate as cross-linker and 2,2-azobisisobutyronitrile (AIBN) as initiator. The obtained MINPs were characterized by Fourier transform-infrared and field emission scanning electron microscopy. Factors influencing the efficiency of UAMSPE such as sonication time, volume of eluent solvent and amount of sorbent were investigated using a central composite design and the optimal points were identified as 4 min of sonication time, 380 μL of eluent solvent and 30 mg of sorbent. Under optimized conditions, the proposed method has linear responses in the range of 0.2-2000 ng mL-1 , with a satisfactory limit of detection of 0.04 ng mL-1 and limit of quantification of 0.11 ng mL-1 .

Assessment of immunoglobulin capture in immobilized protein A through automatic bead injection

The repeatable immobilization of molecular recognition elements onto particle surfaces has a strong impact on the outcomes of affinity-based assays. In this work, an automatic method for the immobilization of immunoglobulin G (IgG) onto protein A-Sepharose microbeads was established through the flow programming features of the portable lab-on-valve platform using micro-bead injection spectroscopy. The reproducible packing of protein A-microbeads between two optic fibers was feasible, allowing on-column probing of IgG retention. The automation of solutions handling and the precise control of time of IgG interaction with the beads rendered repeatable immobilization cycles, within a short timeframe (<2 min). The proposed method featured the preparation of disposable immunosorbents for downstream analytical applications, such as immunosensing or microenrichment of target analytes. In-situ quantification of IgG@protein A-microbeads was carried out using a horseradish peroxidase-labeled detection IgG. The colorimetric oxidation of 3,3′,5,5′-tetramethylbenzidine was monitored on-column. Quantitation of mouse and human IgG immobilized@protein A-microbeads was achieved for loading masses between 0.1 and 0.4 μg per ca. 5.5 mg of sorbent. The implemented detection strategy allowed the quantification of human IgG in certified human serum (ERM®- DA470k/IFCC) and spiked saliva, yielding recoveries of 102–108% and requiring minimal volume (1–15 μL) from serum and saliva.

Efficient adsorption of Cd(ІІ) ions from aqueous media onto a semi‐interpenetrating bio‐composite

AbstractNew bio‐composite, semi‐interpenetrating biopolymers (obtained from hydrolyzed carboxymethyl cellulose grafted polyacrylonitrile [h‐CMC‐g‐PAN] and sodium alginate [Na‐Alg] using CaCl2 as a cross linker; semi‐interpenetrating biopolymers [s‐IPNs]) have been prepared and fully characterized using spectroscopic (FTIR, scanning electron microscopy, EDS), elemental analysis, and thermal analysis measurements measurements. The morphology and structure of these s‐IPNs are different from those obtained with solely h‐CMC‐g‐PAN and Na‐Alg indicating successive functionalization. The availability of the functional‐rich bio‐composites has afforded an excellent opportunity to test them as sorbents for the uptake of toxic Cd(II) ions from aqueous media. Subsequently, the uptake of Cd(II) ions was shown to be dependent on the pH, shaking time, temperature, amount of sorbent, and the initial concentration of the Cd(II) ions. The maximum Cd(II) ion uptake was 99.5% at pH 6, using 50 mg of sorbent with 120 min shaking time at 25°C. The adsorption isotherm fitted well with Langmuir model, with calculated maximum adsorption capacity 49.75 mg g−1. The kinetic studies were modeled using a pseudo second‐order reaction. The thermodynamic parameters (ΔHo, ΔGo, and ΔSo) of the uptake of Cd(II) ions onto s‐IPNs were found to be −13,176.07 Jmol−1, −4,572.7 Jmol−1, and 28.87 J K−1 mol−1, respectively, verifying spontaneous exothermic process. Successive desorption and reusability of s‐IPNs for the uptake of Cd(II) indicated, its high efficiency over three cycles.

Preconcentration of Lead in Blood and Urine Samples Among Bladder Cancer Patients Using Mesoporous Strontium Titanate Nanoparticles.

In this work, mesoporous strontium titanate nanoparticles (SrTiO3 NPs) were synthesized through a single-step combustion process and were characterized by FT-IR, XRD, SEM-EDX, and TEM. The effects of main parameters that may influence the extraction process (i.e., pH, sorbent amount, time of extraction, eluting agent, and the presence concomitant ions) were investigated. The optimum extraction was achieved at pH 6, 50mg of sorbent, 20-min shaking time, and 4.0mL of 0.1molL-1 thiourea as desorption agent. Under these conditions, the maximum adsorption capacity was 155.6mgg-1 with a preconcentration factor of 250 (for a 1000mL sample solution). The calibration graph was linear up to 1000μgL-1 and the limit of detection was 1.75μgL-1. The precision (as relative standard deviation) was 2.53% (n= 10). The procedure was employed for the preconcentration of Pb2+ from blood and urine samples of bladder cancer patients before its determination by FAAS.

Applicability of a magnetic bucky gel for microextraction of mercury from complicated matrices followed by cold vapor atomic absorption spectroscopy

ABSTRACTA new eco-friendly bucky gel nano sorbent consisting of magnetic grapheneoxide (MGO) and an ionic liquid (IL) was used based on dispersive extraction technique followed by cold vapor atomic absorption spectroscopy for determination of mercury in river water, milk, omega-3 supplements, and lipstick. The optimum conditions for extraction were 50 mg of sorbent (mass ratio IL/MGO: 26), 8 min vortexing, acetate buffer pH = 4, and for desorption 3 min vortexing of HNO3 (1 mL). The limits of detection, quantification, preconcentration factor and extraction recovery were found at 0.57, 1.88 µg L−1, 21 and 84%. Relative standard deviation (RSD) was 6.5% (n = 3).

Use of Basolite® F300 metal-organic framework for the dispersive solid-phase extraction of phthalic acid esters from water samples prior to LC-MS determination

In the present work, a commercial metal-organic framework (Basolite® F300) has been applied for the first time as dispersive solid-phase extraction (dSPE) sorbent of eight phthalic acid esters (PAEs) (butyl benzyl phthalate, bis-2-n-butoxyethyl phthalate, bis-isopentyl phthalate, bis-n-pentyl phthalate, dicyclohexyl phthalate, di-(2-ethylhexyl) phthalate -DEHP-, di-n-octyl phthalate and diisononyl phthalate) and an adipate (bis (2-ethylhexyl) adipate), which is utilized as a PAE substitutive. Milli-Q, pond, tap and waste water were selected as samples. Dihexyl phthalate-3,4,5,6-d4 was used as procedural internal standard. High-performance liquid chromatography mass spectrometry was used for the determination of the target compounds. Optimum dSPE conditions were the following: 50 mL of the water sample (pH 6.0), 120 mg of sorbent and 15 mL of ACN as elution solvent. For the validation of the method, matrix-matched calibration and trueness of the method were addressed, obtaining determination coefficients (R2) higher than 0.9905 and relative recovery values between 70 and 118 % (RSDs < 20 %). The limits of quantification of the method were in the range 22–69 ng/L. Matrix effects were also studied. Different real samples were analysed, finding DEHP in all of them at the low µg/L level.

Mucor pusillus immobilized Amberlite XAD-4 biocomposites for preconcentration of heavy metal ions by solid-phase extraction method

BackgroundSolid phase extraction has been an effective tool for the determination of metal ions at trace or sub trace level from environmental aquatic streams. Sensitivity, accuracy, versatility and reusability of adsorbent entitle the solid phase as effective technique for the determination of metal ions.MethodsA solid phase extraction procedure has been described for the determination of Cd, Cu, and Pb by High Resolution–Continuum Source Flame Atomic Absorption Spectrometry HR-CS FAAS using a mini-column of Mucor pusillus (Lindt., 1886) immobilized on Amberlite XAD-4. Method has been optimized by changing the pH of analyte solution, solid phase dosage, volume of eluents, flow rate of sample solution and volume of the sample solutions.ResultsThe recoveries of Cd, Cu, and Pb under the optimum conditions were 99±3%, 97±2% and 96±2%, respectively. The resulting preconcentration procedure ensured a 50-fold improvement in the sensitivity of the elements. The detections limits were 62, 74 and 235 ng/mL for Cd, Cu, and Pb before enrichment, respectively. The method was validated by analysis of tomato leaves reference materials (SRM 1573a).ConclusionsThe proposed enrichment method has been successfully applied for the determination of Cd, Cu, and Pb in tomato leaves and water samples with a relative error ≤8%. This method is simple, sensitive, and accurate especially for water sample, only 200 mg of sorbent are required to capture the analytes. It can be concluded that the use of Mucor pusillus (Lindt., 1886) enhanced the sorption ability of Amberlite XAD-4 resin for the retention of Cd, Cu, and Pb.

Ultrasonically synthesis of Mn- and Cu- @ ZnS-NPs-AC based ultrasound assisted extraction procedure and validation of a spectrophotometric method for a rapid preconcentration of Allura Red AC (E129) in food and water samples

This study is devoted on Allura Red as food colorant preconcentration and determination in beverage, fruit juice and drink water samples is based on usage of Mn- and Cu- @ ZnS-NPs-AC as new sorbent for ultrasound-assisted-dispersive solid-phase microextraction (UA-DSPME) combined with ultraviolet–visible spectrophotometric based method (UV–Vis). Contribution of volume of eluent, pH, sorbent mass and sonication time on response following conduction of 28 experiments were optimized and investigated while their significantly justified according to p-value. Values of “Prob > F” less than 0.0500 is proportional with their significant influence on recovery of analyte. Under the optimum conditions 0.14 mL of THF; pH of 2.5; 8 mg of sorbent and 3 min sonication time guide and help achievement of limit of quantification (LOQ) and limit of detection (LOD) of 6.08 and 20.26 ng mL−1, respectively. The accuracy of method was validated according to calculation of recovery following spiking 400 and 600 ng mL−1 to blank solution and recovery as more reliable indication of accuracy 93.41 and 102.17% recoveries with RSD < 3.5%, which demonstrate the successful applicability of present method for real sample analysis. The maximum sorbent capacity was 50.0 mg g−1 based on Langmuir isotherm as best model with high correlation coefficient. Combination of UA-DSPME and UV–Vis lead to higher sensitivity and lower cost for accurate and repeatable monitoring of Allura Red level in beverage, fruit juice and drink water samples with acceptable recovery and reasonable RSD%.

Nitrogen doped nano porous graphene as a sorbent for separation and preconcentration trace amounts of Pb, Cd and Cr by Ultrasonic assisted in‐syringe dispersive micro solid phase extraction

Nitrogen doped nano porous graphene was used as an efficient sorbent in solid‐phase extraction process for simultaneous separation and pre‐concentration of metal ions lead (II), cadmium(II), and chromium(III)) in biological samples. Ultrasonic assisted in‐syringe dispersive micro solid phase extraction coupled with micro sampling atomic absorption spectrometry was utilized for the determination of metal ions. Nitrogen doped nano porous graphene was synthesized as a nano sorbent by chemical vapour deposition method. Methane and aniline were used as carbon and nitrogen sources. The characterization of sorbent was performed by field emission scanning electron microscope, transmission electron microscopy, atomic force microscope, fourier transform infrared, chemical element analysis and raman analysis. Effective parameters on the extraction efficiency such as pH, sorbent dosage, eluent volume and eluent concentration were optimized by central composite design and desirability function. Experimental results indicate that the optimal conditions for this extraction were pH = 6.4, 1.42 mg of sorbent, 100 μL of eluent, and 0.84 mol L‐1 of eluent concentration. The detection limits are as low as 1.5, 0.3 and 0.9 μg L‐1 for lead, cadmium, and chromium, respectively. The intra‐day precisions were 3.6, 4.38 and 2.94 and Inter‐day precision were 4.83, 5.26 and 4.52 for lead, cadmium, and chromium, respectively. Method performance was investigated by determination of mentioned heavy metals in complicated biological matrixes such as human plasma, urine and saliva samples with good recoveries.

Determination of phthalic acid esters in water samples using core-shell poly(dopamine) magnetic nanoparticles and gas chromatography tandem mass spectrometry

In this work, the first application of core-shell poly(dopamine) magnetic nanoparticles as sorbent for the extraction of a group of eleven phthalic acid esters of interest (i.e. diethyl phthalate (DEP), dipropyl phthalate (DPP), dibutyl phthalate (DBP), bis-isopentyl phthalate (DIPP), bis-n-pentyl phthalate (DNPP), benzylbutyl phthalate (BBP), dicyclohexyl phthalate (DCHP), di-(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DNOP), diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP)) and one adipate (bis (2-ethylhexyl) adipate, DEHA) from different water samples (Milli-Q, mineral, tap, pond and waste water) is proposed. Analysis were carried out by gas chromatography triple quadrupole tandem mass spectrometry. Parameters that affect the extraction performance were optimized following a step by step approach, being the optimum conditions the extraction of water at pH 6, with 60mg of sorbent and the elution with 6mL of dichloromethane. The methodology was validated for the five selected water samples using DBP-d4 as internal standard. Determination coefficients of matrix-matched calibration curves were above 0.9904 in all cases while relative recovery values ranged between 71 and 120%, with relative standard deviation values below 19%. The limits of quantification of the method ranged between 9 and 20ng/L. Matrix effects were found for most analytes and water samples. Real water samples were also analyzed, finding DEP and DBP at concentrations below 4.20 and 1.23μg/L, respectively, in mineral, tap and waste water. DCHP, DEHP and BBP were also found in some of the samples at concentrations below the LOQs of the method.

Micro-solid phase extraction of benzene, toluene, ethylbenzene and xylenes from aqueous solutions using water-insoluble β-cyclodextrin polymer as sorbent

Water-insoluble β-cyclodextrin polymer was synthesized by chemical cross-linking using epichlorohydrin (EPI) as a cross-linker agent. The produced water-insoluble polymer was used as a sorbent for the micro-solid phase extraction (μ-SPE) of benzene, toluene, ethylbenzene and xylenes (BTEX) from water samples. The μ-SPE device consisted of a sealed tea bag envelope containing 15mg of sorbent. For the evaluation of the extraction efficiency, parameters such as extraction and desorption time, desorption solvent and salt concentration were investigated. At an extraction time of 30min in the course of the extraction process, analytes were extracted from a 10mL aqueous sample solution. The analytes were desorbed by ultrasonication in 200μL of acetonitrile for 20min. Analysis of the analytes was done by a gas chromatography-flame ionization detector (GC–FID) system. The enrichment factor (EF) was found to be in the range 23.0–45.4 (EFmax=50.0). The method provided linearity ranges of between 0.5 and 500.0ng/mL (depending on the analytes), with good coefficients of determination (r2) ranging between 0.997 and 0.999 under optimized conditions. Detection limits for BTEX were in the range of between 0.15 and 0.60ng/mL, while corresponding recoveries were in the range of 46.0–90.0%. The relative standard deviation of the method for the analytes at 100.0ng/mL concentration level ranged from 5.5 to 11.2% (n=5). The proposed method was concluded to be a cost effective and environmentally-friendly extraction technique with ease of operation and minimal usage of organic solvent.

Nanofibers mat-based solid-phase extraction method for the pretreatment of urine samples and its application in the primary study on the disposition of nonylphenol after long-term low-level exposure in rats.

A method was established for the analysis of nonylphenol (NP) in rat urine samples based on a solid-phase extraction (SPE) procedure with an amino functionalized polyacrylonitrile nanofibers mat (NH2-PAN NFSM) as sorbent coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The calibration curves prepared in three different days showed good linearity over a wide range of NP concentrations from 0.1 to 100.0ng/mL. It was remarkable that the proposed NH2-PAN NFsM based SPE method showed superior extraction efficiency with the consumption of only 4mg of sorbent and 500μL of eluent. The eluent without any further concentration was directly analyzed by HPLC-MS/MS. As a result, a simple and effective sample preparation was achieved. In addition, the notable lower detection limit (LOD) of 0.03ng/mL revealed the excellent sensitivity of the proposed method in comparison with that in literatures. The recoveries ranged from 85.0% to 114.8% with the relative standard deviations (RSDs) ranging from 7.5% to 13.7%, which were better than or comparable to those from the published methods, suggesting high accuracy of the proposed method. The proposed method was applied in primary study on the disposition of nonylphenol after long-term low-level exposure in rats, providing information for health risk assessment on the real scenarios of NP exposure. NH2-PAN NFsM shows great potential as a novel SPE sorbent for the analysis of biological samples.

Detection of β-agonists in pork tissue with novel electrospun nanofibers-based solid-phase extraction followed ultra-high performance liquid chromatography/tandem mass spectrometry.

A selective analytical method based on packed-fiber solid-phase extraction and ultra-high performance liquid chromatography-tandem mass spectrometry (PFSPE-UPLC-MS/MS) has been developed for determination of six β-agonists (clorprenaline, bambuterol, clenbuterol, brombuterol, mabuterol, and penbuterol) in pork tissue. Polystyrene-polymeric crown ether (PS-PCE) composite nanofibers were fabricated by electrospinning and utilized to prepare the homemade extraction columns. With optimal conditions, all analytes were separated very well and the blank pork did not disturb the determination, and the linearity is good in a range of 5.0μg/kg-25.0μg/kg. The recoveries were 79.3-110.1%. RSDs for intra-day were in the range of 1.5-10.5% and RSDs for inter-day were 4.7-11.8%. Above all, only 5mg of sorbent and 200μL of elution solvent were favorable to directly extract all analytes in a complex matrix. The method is simple and cost-effective, and has the potential to be applied to quantitatively analyze the concentrations of polar species in food samples containing complex matrix.

Determination of tetracyclines in bovine milk using laccaic acid-loaded magnetite nanocomposite for magnetic solid-phase extraction.

An efficient magnetic sorbent of laccaic acid-loaded magnetite nanocomposite was successfully synthesized for extraction and preconcentration of tetracyclines (TCs) from bovine milk sample. The synthesized nanocomposite was characterized by scanning electron microscopy and Fourier transform-infrared spectroscopy. Determination of the extracted TCs was performed by high performance liquid chromatography. Parameters affecting the efficiency of magnetic solid-phase extraction were studied and optimized. The best adsorption conditions were 80 mg of sorbent, 50 mL of sample volume, pH 7, 45°C and 20 min; the elution conditions were 0.5 mL of acetonitrile, pH 5.5, 75°C and 5 min. Under optimized conditions, the preconcentration factor of TCs was 100. The calibration curves were linear at a concentration range of 10-300 μg/kg for oxytetracycline and TC, and 5-300 μg/kg for chlortetracycline and doxycycline. The limit of detection was from 3.2 to 7.1 μg/kg, the limit of quantification was from 10.7 to 23.7 μg/kg, the relative standard deviation was between 2.8 and 5.3 and the recoveries were between 95.2% and 106.2%. In terms of the proposed procedure, the developed method was successfully applied for TCs detection in bovine milk samples.

Pb(II) Removal Process in a Packed Column System with Xanthation-Modified Deoiled Allspice Husk

The present research dealt with lead removal using modified Pimenta dioica L. Merrill as biosorbent in a batch and in continuous flow column systems, respectively. The allspice husk residues were modified first with a treatment through the xanthation reaction. For the adsorption tests, the atomic adsorption spectrophotometry method was used to determine the lead concentrations in the liquid samples. In the kinetic batch study (10 mg of sorbent in 10 mL of 25 mg L−1 lead solution), the removal efficiency was 99% (adsorption capacity of 25.8 mg g−1). The kinetic data followed the pseudo-second-order model. The adsorption isotherm was fitted to the Freundlich model, where constants were Kf and 1/n (8.06 mg(1-1/n) g−1 L1/n and 0.52), corresponding to adsorption capacities of 8 and 62 mg g−1, at liquid equilibrium concentration of 1 and 50 mg L−1, respectively. In the continuous flow systems where lead solution of 50 mg L−1 was treated in 2 columns of 5 cm (4.45 g) and 10 cm (9.07 g) bed heights, the dynamic adsorption capacity obtained by fitting the Thomas model was 29.114 mg g−1 and 45.322 mg g−1, respectively.