Phase Extraction Procedure Research Articles

Quantifying the microstructure and phase assemblage of alkali-activated fly ash/slag materials by EDS mapping analysis

Accurately quantifying the proportions and distributions of reaction products is crucial for interpreting reaction mechanisms and microstructure evolution in alkaline activated fly ash/slag pastes. However, existing techniques are limited in their ability to provide a comprehensive and visual analysis. This paper presents a versatile energy dispersive X-ray spectroscopy (EDS) mapping analysis that enables image enhancement, phase extraction, and component classification in the alkaline-activated materials (AAMs) -irrespective of the nature and quality of element mappings. The proposed methodology effectively removes the detection noise that inherently existed in EDS mappings, subsequently reinforcing the accuracy of the clustering analysis. The phase extraction procedure allows for obtaining the proportion of pores, reaction products, and unreacted solid precursors (SPs). Moreover, the component classification procedure enables further categorization of the reaction products and unreacted SPs. By analyzing the element ratios and shortest distances, the chemical compositions and spatial distributions of various reaction products could be revealed. Through the application of different analysis schemes, a consistent tendency was obtained, validating the practicability and reliability of this methodology.

Preconcentration of lead in water samples using combined cloud point‐solid phase extraction based on TiO2/Mn3O4/Fe3O4 nanocomposite

AbstractIn this work, the TiO2/Mn3O4/Fe3O4 nanocomposite was successful developed for enrichment of lead ions by using combined cloud point‐solid phase extraction. Lead ions were then determined by GF‐AAS spectroscopy. The nanocomposite was characterized by SEM, EDX, and XRD techniques. The result showed that the nanocomposite is composed of relatively uniform granules with particle size distribution in the range of 40÷80nm. The combined cloud point‐solid phase extraction procedure was optimized for lead ions with the optimal parameters as the absorbent dosage of 10 mg, the extraction time of 40 min, 10 mL of 10 % Triton X‐100, 1 mL of 1M NaCl in neutral media at 80°C. The parameters for the elution of Pb2+ ions such as concentration, volume, and the time of elution were also studied. The results showed that the elution efficiency of Pb2+ ions reached 97.0 % using 5 mL of HNO3 1M with continuous shaking for 5 minutes. Under optimized conditions, the linear range was 0.5÷80.0 μg/L of Pb2+ ions (r2 = 0.998) with a detection limit of 0.27 μg/L. The relative standard deviation was calculated to be 5.61 % and the recovery efficiency of the method was about 96.30 %. The studied method was applied for the determination of lead content in water samples.

Determination of Flumethrin and Tau-Fluvalinate Pyrethroid Insecticides in Surface and Groundwater by Photochemically Induced Fluorescence (PIF)

Flumethrin and tau-fluvalinate pyrethroid insecticides were determined in natural water using photochemically induced fluorescence (PIF). As these pesticides are not naturally fluorescent, PIF using ultraviolet irradiation was employed to produce highly fluorescent derivatives. This method was optimized for irradiation interval, solvent and pH. The calibration curves were linear with limits of detection (LOD) from 0.5 to 73.8 ng mL−1 without matrix effects. Applications were carried out in aqueous solutions on tap water, seawater, well water and river water from Niayes, Senegal and the Brest, France using solid phase extraction and standard addition procedures. The samples were analyzed with mean recoveries between 99.0 and 109.0%. The analytical performances of these systems were favorable compared with published photoinduced fluorescence methods for the determination of pyrethroids. The results show that the developed PIF method is suitable for the determination of trace organic pollutants in natural waters.

Adsorption and determination of Lead in water and human urine samples based on Zn2(BDC)2(DABCO) MOF as polycaprolactone nanocomposite by suspension micro solid phase extraction coupled to UV–VIS spectroscopy

Today, the safety of water resource is the most important challenges which was reported by health and environment organizations. Water pollution can be created by hazardous contaminants of environmental pollutions. Lead as a heavy metal has carcinogenic effects in humans. Metal organic framework (MOF) is a highly porous material with different application. The Zn2(BDC)2(DABCO) is a good candidate of MOF based on zinc metal (Zn-MOF) with potential adsorption/extraction. In this work, Zn2(BDC)2(DABCO) MOF as polycaprolactone (PCL) nanocomposite were applied for lead adsorption/extraction from 50 mL of aqueous solution by ultra-assisted dispersive suspension-micro-solid phase extraction procedure (USA-S- µ-SPE) at pH=8. The samples were characterized by the FTIR, the XRD analysis, the FE-SEM and the BET surface area. The effect of parameters was investigated on lead absorption before determined by UV–VIS spectroscopy. The linear range, the detection limit (LOD) and enrichment factor of adsorbent were obtained 0.05-1 mg L-1, 0.25 μg L-1 and 48.7, respectively (r = 0.9992, RSD%=3.65). The absorption capacity of Zn2(BDC)2(DABCO) MOF for 50 mg L-1 of standard lead solution were obtained 133.8 mg g-1 for 0.25 g of adsorbent. The results indicate that this nanocomposite can have a good potential to develop different adsorbents.

A rapid extraction of toxic styrene from water and wastewater samples based on hydroxyethyl methylimidazolium tetrafluoroborate immobilized on MWCNTs by ultra-assisted dispersive cyclic conjugation-micro-solid phase extraction

The styrene affected on human health and caused cancer and dysfunction in the central nervous system (CNS) and liver. So, sensitive techniques for the separation and determination of styrene in water and wastewater samples are necessary. In this study, a novel task-specific ionic liquid (TSIL) immobilized on multi-walled carbon nanotubes (MWCNTs@[Hemim][BF4]) was synthesized with a new approach for extraction of styrene from water samples by ultra-assisted dispersive cyclic conjugation-micro-solid phase extraction procedure (USA-DCC-µ-SPE). Due to procedure, 30 mg of MWCNTs@[Hemim][BF4] was mixed with 20 mL of water or standard styrene solution (0.001–6.5 mg L−1) in the centrifuge Pyrex tube (CPT, 20 mL) by stirring for 12 min (25 °C). After extraction of styrene based on the cation/anion π–π interactions and imidazolium ring of TSIL with π system/vinyl group of styrene, the MWCNTs@[Hemim][BF4] adsorbents were collected at the bottom of the conical tube. The upper liquid phase set aside by the auto-sampler and 0.2 mL of ethyl benzene added to the remained solid phase at 70 °C. After back extraction of styrene in ethyl benzene, the styrene values were measured with a gas chromatography-flame ionization detector (GC-FID). All effective parameters such as the sample volume, the amount of sorbent, temperature, and the sonification time were studied. The linear range (LR), the detection limit (LOD) and re-usage of adsorbent were obtained 0.001–6.5 mg L−1, 0.26 μg L−1 and 18 times, respectively (r = 0.9997, RSD%=1.45). Due to TGA curve, the weight loss (7 wt%) for MWCNTs@[Hemim][BF4] was occurred at more than 350 °C. The absorption capacities of MWCNTs@[Hemim][BF4] and MWCNTs for 100–200 mg L−1 of standard styrene solution were obtained 183.2 mg g−1 and 24.8 mg g−1, respectively. The procedure was validated by GC–MS and spiking samples.

Optimized Synthesis of Molecularly Imprinted Hybrid Polymer by Factorial Design for Selective Caffeine Extraction in Surface Water

A hybrid imprinted polymer (HMIP) was synthetized via sol-gel technique in aqueous solution for caffeine separation from environmental waters samples. The optimal conditions of synthesis were stablished by application of a 23 full factorial experimental design with three factors: ratio of functional monomer and cross-linker reagent, and acid or basic catalyst (HCl or NH4OH). The HMIP obtained with the factorial designs was 22.5 times more selective for caffeine than control polymer, with an adsorption mechanism of pseudo-second order with two sorption sites. The maximum equilibrium adsorption capacity was 1.91 mg g-1 that was maintained until ten cycles of reuse, indicating their excellent stability. The material was 21 times more selective for caffeine than for its analogous molecules (theophylline and theobromine). HMIP was applied in solid phase extraction (SPE) procedure and caffeine extraction of surface water had good recoveries (93.0%).These results demonstrated that the factorial experimental design resulted in an efficient and selective sorbent for caffeine with a reduction of number of synthesis and problems of trial‑and‑error protocol as well as reagents consumption decrease.

Solid phase extraction of β-sitosterol and α-tocopherol from sunflower oil deodorizer distillate using desilicated zeolite

In this study, the efficiency of using zeolite-based adsorbents in a solid phase extraction (SPE) procedure of α-tocopherol and β-sitosterol isolation from Sunflower Oil Deodorizer Distillate (SuDOD) with­out pre-treatment was investigated. The results showed that 99.2% α-tocopherol and 97.3% β-sitosterol were suc­cessfully isolated as pure fractions from SuDOD, when desilicated ZSM-5-type zeolite (DSiZSM-5) was used as adsorbent on a SPE. A simple and rapid HPLC method for simultaneous α-tocopherol and β-sitosterol analysis was developed and validated according to AOAC guidelines. It was found that the inclusion of a DSiZSM-5 SPE step increased the precision of the α-tocopherol and β-sitosterol analysis. In conclusion, DSiZSM-5 zeo­lite was proven to be an efficient adsorbent which can be used not only for the recovery of α-tocopherol and β-sitosterol from SuDOD in industrial scale, but also in a laboratory scale clean-up method prior to the analysis of α-tocopherol and β-sitosterol.

Determination of 42 veterinary drug residues in common animal derived food by dispersive solid phase extraction coupled with liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem mass spectrometry method, coupled with a dispersive solid phase extraction (DSPE) procedure for sample preparation, was developed to determine 13 classes of 42 veterinary drugs in four representative animal-derived foods. The analytes were dispersed with water, extracted with acetonitrile containing 5% (v/v) formic acid, salted out by salts, and purified by DSPE. The analytes were separated on a C18 column (100 mm×2.1 mm, 2 μ m) with gradient elution using the mobile phase containing methanol and 0.1% (v/v) formic acid aqueous solution. Electrospray ionization-mass spectrometry was performed in multiple reaction monitoring mode for analysis of the 42 compounds. The correlation coefficients of the standard calibration curves for the 42 veterinary drugs were all above 0.995. Most recoveries at three spiked levels in the four representative matrixes ranged from 65.8% to 135.5%, with relative standard deviations of 0.5%-14.2% (n=6). The limits of detection (LODs, S/N=3) and the limits of quantification (LOQs, S/N=10) were 0.01-1.68 μ g/kg and 0.01-5.62 μ g/kg, respectively. The method is simple, rapid, sensitive, and suitable for the simultaneous determination of the 42 veterinary drugs in animal-derived food.

Twin image removal in digital in-line holography based on iterative inter-projections

A simple and efficient phase retrieval method based on the iterative inter-projections of the recorded Fourier modulus between two effective holographic planes is developed to eliminate the twin image in digital in-line holography. The proposed algorithm converges stably in phase extraction procedures without requiring any prior knowledge or sophisticated support of the object and is applicable to lensless Gabor and Fourier holography as well as holographic microscopy with imaging lenses. Numerical and experimental results suggest that the spatial resolution enhancement on the reconstructed image can be achieved with this technique due to the capability of recovering the diffraction phases of low-intensity signals.

Development of a method for speciation of inorganic arsenic in waters using solid phase extraction and electrothermal atomic absorption spectrometry

ABSTRACTA solid phase extraction (SPE) procedure based on Amberlite IRA 900 resin was developed for speciation and separation of inorganic arsenic species (III, V) and total As in water samples. The As species and total As in eluent solutions were determined by electrothermal atomic absorption spectrometry (ETAAS) using Ni chemical modifier with 1200°C pyrolysis temperature. Experimental parameters such as pH value, sample volume, flow rate, volume and concentration of eluent solution for As(V) were optimised and 98.0 ± 1.9% recovery was found at pH 4.0. Experimental adsorption capacity of the resin for As(V) was investigated and 229.9 mg g–1 was found. Under optimised experimental conditions, instrumental parameters such as limit of detection (LOD) and limit of quantification (LOQ) found were 0.126 and 0.420 µg L–1, respectively. Interference effects of coexisting ions in the sample matrix on the recovery of As(V) were investigated. Concentration of As(III) was obtained by subtracting As(V) concentration found at pH 4.0 from total As(III + V) found at pH 8.0. The accuracy of the method proposed by using the resin was tested for analysing As species in a waste water standard reference material (SRM, CWW-TM-D) and spiked real water samples with recovery above 95%. The method proposed was also applied to the determinations of As species and total As in underground hot waters and tap water with relative error below 3%.

New Spectrofluorimetric Method for Determining Serotonin: Application to Human Urine

In this present paper, we investigate the development of simple, rapid, accurate, reproducible and sensitive methods for the determination of serotonin (5-HT) in urine. For this purpose stationary fluorescence was used as method. With regard to the analysis of serotonin, the liquid-liquid extraction (LLE) solid phase extraction (SPE) and standard addition procedures were used. Several physicochemical factors affecting the sensitivity of the fluorescence intensity of serotonin were optimized, including the system of solvent (organic, micellar), the pH and the salts. The study of the analytical performances of the method led to very low limits of detection (LOD) varying between 0.1 and 3 ng/mL and to limits of quantification (LOQ) ranging between 0.4 and 10 ng/mL. This confirms the sensitivity of the method. Thus the low values of standard deviations (DRS) (between 0.3 and 6.6%) testify the good reproducibility of the measurements with satisfactory covering rate (89 to 111%). Accordingly, our results show that the spectrofluorimetric method is simple, fast and sensitive and can be applied to the routine analysis and does not require expensive equipment nor tiresome chemical pretreatments.

Phase extraction in disordered isospectral shapes

The phase of the electronic wave function is not directly measurable but, quite remarkably, it becomes accessible in pairs of isospectral shapes, as recently proposed in the experiment by Moon et al. [Science 319, 782 (2008)]. The method is based on a special property, called transplantation, which relates the eigenfunctions of the isospectral pairs, and allows us to extract the phase distributions, if the amplitude distributions are known. We numerically simulate such a phase extraction procedure in the presence of disorder, which is introduced both as Anderson disorder and as roughness at edges. With disorder, the transplantation can no longer lead to a perfect fit of the wave functions, however we show that a phase can still be extracted-defined as the phase that minimizes the misfit. Interestingly, this extracted phase coincides with (or differs negligibly from) the phase of the disorder-free system, up to a certain disorder amplitude, and a misfit of the wave functions as high as ~5%, proving a robustness of the phase extraction method against disorder. However, if the disorder is increased further, the extracted phase shows a puzzle structure, no longer correlated with the phase of the disorder-free system. A discrete model is used, which is the natural approach for disorder analysis. We provide a proof that discretization preserves isospectrality and the transplantation can be adapted to the discrete systems.

A RAPID UHPLC METHOD FOR THE SIMULTANEOUS DETERMINATION OF SELECTED B-BLOCKERS, NSAIDS, AND THEIR METABOLITES IN HUMAN URINE AND WATER SAMPLES

A rapid Ultra High Performance Liquid Chromatography (UHPLC) method for the simultaneous determination of β-blockers (sotalol SOT, metoprolol MET, propranolol PRO), Non-steroidal Anti-inflammatory Drugs (NSAIDs) (paracetamol PAR, ketoprofen KET, salicylic acid SAL), and their metabolites (paracetamol sulfate PAR-S, paracetamol glucuronide PAR-G, ketoprofen glucuronide KET-G, o-desmethylmetoprolol D-MET, α-hydroxymetoprolol MET-H, 4′-hydroxypropranolol sulphate PRO-S) is presented in this paper. The separation of twelve determined substances was conducted by means of a C18 Fast Gradient monolithic column (50 mm × 2 mm) in no longer than 7.5 min. The amounts of analytes introduced onto the column varied from 0.09 ng to 0.69 ng in a 1-μL injection. The method was validated for the determination of these substances in human urine and tap water, according to Solid Phase Extraction (SPE) procedures. The linearity ranges for the analyzed substances were (μg/mL): 0.60–40 for PAR-G; 0.69–44 for PAR-S; 0.60–42 for PAR; 0.33–40 for SOT; 0.30–35 for MET-H; 0.27–40 for DMET; 0.40–45 for SAL; 0.33–40 for PRO-S; 0.40–36 for MET; 0.45–42 for PRO, 0.36–46 for KET, and for 0.42–40 KET-G. The described method was successfully applied to water samples and to urine from patients who were administered the aforementioned drugs.

Flow-Injection Determination of Benzimidazole Fungicides in Natural Waters with Copper(II)-Hydrogen Peroxide Chemiluminescence

A simple, sensitive, and rapid flow-injection method is reported for the determination of benzimidazole fungicides (BFs): fuberidazole, benomyl, and carbendazim. The method is based on enhancement of the chemiluminescence (CL) signal generated during the reaction of BFs with hydrogen peroxide and copper(II) in alkaline condition in the absence of luminescent reagents. Linear calibration graphs were obtained in the concentration range of 5–2000, 25–2000, and 25–5000 ng mL−1 for fuberidazole, benomyl, and carbendazim, respectively. The relative standard deviations (n = 4) were in the range 1.2–2.6% with limits of detection (S/N = 3) 3 ng mL−1 for fuberidazole, and 15 ng mL−1 for benomyl and carbendazim. The proposed method allowed 120 injections h−1. The effect of common anions, cations, and some pesticides on the determination of BFs was also examined. The method is applied to determine BFs in spiked natural water samples using Sep-Pak C18 cartridges for solid phase extraction and preconcentration procedure. Recoveries were in the range of 94 ± 1 to 105 ± 1%. The CL mechanism is also discussed briefly.

Application of experimental design in optimization of solid phase extraction of mycophenolic acid and mycophenolic acid glucuronide from human urine and plasma and SPE-RP-HPLC method validation

The aim of this study was to develop and optimize a solid phase extraction (SPE) procedure for purification of mycophenolic acid (MPA) and its metabolite mycophenolic acid glucuronide (MPAG) in biological samples. During optimization process chemometric approach was applied. First, in screening experiments fractional factorial design (FFD) was used for selecting the variables which affected the extraction procedure. The ionic strength of the phosphate buffer in the washing step and the percentage of acetonitrile in the elution step were statistically significant for the recovery of MPAG while the percentage of acetonitrile and pH of the washing solution were statistically significant for that of MPA. Afterwards, the significant variables were optimized using central composite design (CCD). The developed SPE method included phosphate buffer (pH 2.4; 0.056 M) in the washing step, and the mixture of acetonitrile and phosphate buffer of which pH was adjusted to 2.4 (70:30, v/v) in the elution step. The investigation was applied to both urine and plasma and the nature of biological matrix appeared to be of no importance. The extraction from both matrixes showed good repeatability with relative standard deviations up to 6% for MPAG and 8% for MPA, and recovery around 100% for both substances. Furthermore, new SPE-RP-HPLC method for determination of MPA and MPAG in both humane urine and plasma has been validated. The great advantage of this method is the chromatographic run of only 3 min.

Dual gradient LC method for the determination of pharmaceutical residues in environmental samples using a monolithic silica reversed phase column

Detailed below is a simple reversed-phase liquid chromatography (RP-LC) method for the simultaneous separation of up to 21 acidic, basic, and neutral pharmaceuticals using Merck Chromolith Performance RP-C18e monolithic columns with direct ultraviolet (UV) absorption detection. By simultaneously applying a solvent elution gradient program with a mobile phase flow gradient, both a decrease in the overall analysis time and a general increase in peak efficiencies were observed. Mobile phase pH and buffer concentration were optimised using the overall resolution product under applied gradient conditions. Under optimised conditions peak area reproducibility (n = 6) ranged between 0.4 and 9.3%, determined at the method LOQ level. For real sample analysis pharmaceutical residues were extracted using an optimised solid phase extraction (SPE) procedure, utilising Strata-X extraction cartridges, which overall provided the highest relative recovery data in comparison with four other commercially available SPE sorbents (17 out of 20 residues investigated had recoveries over 70%). Complete method precision, including all sample pre-treatment and LC analysis for six spiked river water samples at the 1 and 2 µg L−1 level was between 10 and 29%. Using 1 L volumes of 1 µg L−1 spiked estuarine water samples, the majority of detection limits were found to be in the 10–50 ng L−1 range.

Two Stage Solid Phase Extraction with Subsequent HPLC Isolation for Structure Elucidation of Major Metabolites of (+)-(R)-2-{3-(benzo[1,4]dioxan-2-yl-methylamino)-1-propyl}-3(2H)-pyridazinone (GYKI-16084)

GYKI-16084 – (+)-(R)-2-{3-(benzo[1,4]dioxan-2-yl-methylamino)-1-propyl}-3(2H)-pyridazinone hydrochloride – is a new drug candidate for the treatment of benign prostatic hyperplasia. In our study the major metabolites formed in the rat and dog were isolated from dog and rat urine, then their structures were elucidated by means of MS and NMR. A two stage solid phase extraction (SPE) procedure and a semi-preparative HPLC method were developed utilizing various mechanisms of separation. The major metabolites proved to be isomeric glucuronides of the benzodioxane moiety hydroxylated at positions 6 or 7 and {2-(2-carboxyethyl)-3(2H)-pyridazinone}.

Sandwich holography for simultaneous temperature visualization and heat-transfer coefficient measurement

Sandwich holography is proposed for simultaneous temperature mapping and heat transfer coefficient measurement. The latter task requires the knowledge of the temperature gradient. The remarkable feature of the proposed method is that the temperature gradient is obtained avoiding numerical differentiation, which adds errors to the measured data, as well as phase extraction and phase unwrapping procedures. Theory and experimental results are given.

In vitro culture of Montanoa tomentosa for the production of diterpenic acids

Following a solid phase extraction, GC-MS and GC-FID procedures, the production of three kaurane derivatives (grandiflorenic, kaurenoic and monoginoic acids) was detected in callus and cell suspension batch cultures of Montanoa tomentosa. From different hormonal combinations, the addition of 0.5 mg 2,4-dichlorophenoxyacetic acid l−1 + 2 mg kinetin l−1 increased the accumulation of total kaurenoids in 6 months old calluses to 2.1 mg g−1 dry weight and in cell suspensions cultures up to 0.76 mg g−1 dry weight. Monoginoic acid, which has not been detected before in leaves of wild plants, accumulated in both in vitro systems.

EFFICIENT SOLID PHASE EXTRACTION PROCEDURES FOR ORGANO SILOXANES AND SILANOLS FROM AQUEOUS AND BIOLOGICAL MATRICES

Efficient solid phase extraction (SPE) procedures were established to extract a variety of organosiloxanes and organosilanols at low concentrations from aqueous and biological matrices. The organosilicon materials used in SPE experiments were all 14C-labeled. Use of 14C-labeled materials made it very convenient to determine the SPE process efficiency. For non-polar siloxanes of lower molecular weight, viz., 14C-octa-methyl-cyclotetrasiloxane (D4), 14C-decamethylcyclopenta-siloxane (D5), and 14C-hexamethyldisiloxane (MM), the recoveries from aqueous solutions, using C18 SPE cartridges, were 91 (± 2), 98.6 (± 0.5), and 96.2 (± 2), % respectively. For polymeric siloxane fluids of 350 and 1000 cSt viscosities with number average molecular weights, Mn of ∼9800 and 17,000 respectively, C4 sorbent was preferred. The recoveries for these polymeric siloxanes were 89.3 (± 1.7), and 96 (± 0), % respectively. For polar silanols, styryl-divinylbenzene based polymeric-sorbent ENV+® worked exceptionally well. Using ENV+ sorbent, samples of dimethylsilanediol Me2Si(OH)2, methylsilanetriol MeSi(OH)3, were recovered from aqueous medium with excellent efficiencies (99 and 94 %, respectively). The ENV+ cartridge was also applied to recover very efficiently the metabolites (i.e. hydroxy and hydroxymethyl functional siloxanes) of D4, D5, and MM present in rat urine. The recoveries were >90% in all cases. Recoveries of metabolites of MM and D5from plasma were ∼80 and 66% respectively. The concentrations of the analytes ranged from parts per billion to parts per million. For successful retention of the analytes to the sorbent, it was found to be necessary to place solid NaCl to the top of the SPE cartridge bed, or treat the aqueous matrices with NaCl prior to sample load. HPLC analyses of samples performed following the SPE process showed that the organosilicon materials, including the very reactive silanols, remained unchanged.