Alumina Column Research Articles

Determination of Sedative and Anesthetic Drug Residues in Aquatic Food Products Using Solid Phase Extraction (SPE) and Liquid Chromatography–Tandem Mass Spectrometry (LC–MS/MS)

The residues of sedative and anesthetic drugs in aquatic products are an important factor affecting food safety. In order to screen the residues of sedative and anesthesia drugs in aquatic products, a rapid and sensitive method was established using solid phase extraction (SPE) and high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS). The samples were extracted by 80% aqueous acetonitrile by an alumina column and separated by a C18 column. The mass spectra were determined in positive ion mode. The standard curves were matrix matched and quantified by the external standard method. The results showed that the linear ranges of the drugs in aquatic products were from 0.5 to 100 μg kg−1. The correlation coefficient (R 2) was greater than 0.990 and the detection limits were between 0.001 and 0.322 μg kg−1. The average recovery rate and relative standard deviation were between 78.64% and 112.15% and from 0.41%-8.26%. Overall, the developed method showed promising results for the simultaneous qualitative and quantitative determination of the drug residues in aquatic products.

Herbicidal proteins from Bacillus wiedmannii isolate ZT selectively inhibit ryegrass (Lolium temulentum L.).

The widespread use of chemical herbicides and the growing issue of weed resistance pose significant challenges in agriculture. To address these problems, there is a pressing need to develop biological herbicides based on bacterial metabolites. In this study, we investigated the impact of the cell-free culture filtrate (CFCF) from the ZT isolate, a bacilliform bacterium obtained from diseased wheat seeds, on the germination and seedling growth of various plant species, including wild oat, ryegrass, redroot, wheat, and chickpea. The results revealed that CFCF had a detrimental effect on the fresh and dry weight of stems and roots in most of the studied plants, except chickpeas. The CFCF was further subjected to separation into aqueous and organic phases using chloroform, followed by the division of the aqueous phase into 13 fractions using an alumina column. Notably, both the aqueous phase (20%) and all 13 fractions (ranging from 50% to 83%) displayed the ability to reduce the root length of ryegrass, a monocotyledonous weed. Liquid chromatography-mass spectrometry (LC-MS) analysis identified that fractions 3 and 7, which were effective against ryegrass but not redroot, contained Cry family proteins, including Cry10 Aa, Cry4 Ba, and Cry4 Aa. Additionally, 16s rRNA gene sequencing revealed that the ZT isolate is closely related (98.27%) to Bacillus wiedmannii. Conclusively, metabolites from the ZT bacterium hold promise for monocotyledonous weed-targeted herbicides, providing a constructive strategy to confront agricultural issues tied to chemical herbicides and weed resistance. © 2024 Society of Chemical Industry.

A chromatographic relay conjugated photoredox strategy: S, Se-pharmacophore from alkenes via formal [2+2+1] heteroannulation.

An expedient route to 2-aminodihydrothiophenes and their seleno analogues is reported. A three-component photoredox reaction between alkene, thio(seleno)cyanate, and bromomalonate is employed, generating a carbo-thio(seleno)cyanate intermediate that undergoes a domino of reactions mediated by alumina column chromatography, leading to valuable chalcogen pharmacophores. Mechanistic investigations using DFT and control experiments reveals an intramolecular H-bond responsible for driving the domino forward.

99mTc generator using molybdenum nanoparticles

A novel 99mTc generator was proposed herein using nanoparticles consisting of natural Mo and an alumina column for 99mTc scintigraphy. 99mTc was obtained from 99Mo decay produced via the irradiation of nanoparticles consisting of natural Mo with bremsstrahlung γ-rays using a 30 MeV electron beam. The irradiated nanoparticles were placed in an alumina column, and the 99mTc daughter from 99Mo decay was separated by the removal of the ion-exchanged water or saline. This separation procedure was repeated at regular intervals for one week. The maximum separation yield of 99mTc was 14.4 ± 0.7%, which is sufficiently high to produce 99mTc suitable for medical use.

Establishment and validation of an acid alumina column clean-up for determination of trace citrinin in food samples

Establishment and validation of an acid alumina column clean-up for determination of trace citrinin in food samples

Experimental observations of communication in blackout, topological waveguiding and Dirac zero-index property in plasma sheath

Abstract The plasma sheath causes the spacecraft’s communication signal to attenuate dramatically during the re-entry period, which seriously threatens the astronauts. However, valid experimental protocols have not been obtained hitherto. To realize the propagation of electromagnetic waves in negative permittivity background of the plasma sheath, alumina columns are embedded in the plasma background to form plasma photonic crystals, which can support the coupling of evanescent waves between the alumina columns. We experimentally demonstrate the realization of communication in blackout scenario by achieving a complete passing band in the plasma cutoff region. For high frequency communications in the plasma sheath, electromagnetic wave propagation based on topological edge states is also experimentally demonstrated. Furthermore, we realize a triply-degenerate Dirac cone formed dynamically at the center of the Brillouin zone by modulating the electron density, where electromagnetic wave exhibits high transmittance and does not experience phase accumulation at the Dirac point. Our work thus not only provides an effective approach to overcome the communication blackout problem, but the design can also be served as a promising experimental platform to explore topological electromagnetic phenomena.

Rapid determination of PCDDs, PCDFs and DL-PCBs in foods, feeding stuffs and vegetable oils using new modified acid silica

Polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls are persistent organic pollutants (POPs), which in recent years received huge attention due to their extreme stability, high potential toxicity and bioaccumulation in food chains. The main source of human exposure to these compounds is discovered in foods of animal origin, especially foods rich in fat. The target of the present study was to set up an analytical method for the determination of PCDDs/PCDFs and DL-PCB in vegetable oils, sunflower meals, sunflower seeds, rapeseeds and milk powder. The first step consisted of a semi-automatic Soxhlet extraction for 3 hours, by using a mixture of Hexane: Acetone – 80:20, followed by acid digestion with 55% acid silica and filtration. After concentration, the extract is purified on a multilayer column (silica gel, silica-KOH, silica-H2SO4 anhydrous Na2SO4) followed by an alumina column separation in two fractions (first fraction containing PCDDs/PCDFs and second containing only PCBs). The purified extract was then analyzed by GC/MS/MS. The newly developed approach in our lab was capable to reduce the overall time of sample preparation to seven hours/ per sample. Since the method shows good mean recoveries for all labeled congeners spiked in the samples (for PCDDs/PCDFs – 80% - 110%, for DL-PCBs – 70% - 85%), we assumed the absence of overestimation or underestimation in the analyzed samples.

Analize ugljovodonika (PAH, alkana i bteks) u morskoj vodi luke Valona

In this study, levels of polycyclic aromatic hydrocarbons (PAH), aliphatic hydrocarbons (n-alkanes) and volatile hydrocarbons were determined in water samples of the port of Vlora which is the second largest port in Albania. It is located in Vlora Bay, near Vlora city. Presence of these pollutants in port area is mainly because of ships transport, commercial/passengers processing and the water currents in-side/out-side the port area. Hydrocarbons (PAHs, n-alkanes and BTEX) are generated mainly by the transport (automobiles, ships, trains, etc), extracting/processing of oil industry, coal mine and other industries. Forest burning and their natural background make them very often in environment. Water samples were taken in May 2022 in different stations of the Vlora's port (inside and outside its area). Aromatic and aliphatic hydrocarbons were extracted simultaneously using two steps liquid-liquid extraction (LLE) technique. Firstly, dichloromethane (MeCl2) and after that n-hexane were used as extraction solvents. After extraction, the organic phase was dried with sodium sulfate anhydrous, for water removing. "Clean-up" procedure was realized in an alumina column. After the concentration to 2 ml, the samples were injected in Varian 450 GC equipped with FID detectors. BTEX were analyzed using head space solid phase micro-extraction technique (HS/SPME) by using polydimethylsiloxane fiber (PDMS) followed by GC/FID technique. PAH, n-alkanes and BTEX were found almost in all water samples of Vlora's port. Their presence could be because of anthropogenic factors (elevated activity and ship transport) in the port area. The levels of hydrocarbons in water samples of Vlora's port were higher / comparable than reported levels for them in other stations of the Adriatic Sea, Albania part.

Structural isomers of di-p-benzidithiaoctaphyrins.

The cis and trans structural isomers of di-p-benzidithiaoctaphyrins were synthesized by adopting two different synthetic routes using readily available precursors under acid-catalyzed conditions, and the isomers were separated using basic alumina column chromatography. 1D and 2D NMR spectroscopy were used to deduce the molecular structures of the macrocycles, which also helps to differentiate the cis isomer from the trans isomer. DFT studies revealed that both the cis and trans isomers adopt figure of eight conformations but exhibit clear differences in their structural features, and the trans isomer is more distorted than the cis isomer. Experimental and theoretical studies revealed that both the cis and trans isomers are nonaromatic stable macrocycles and show subtle differences in their structure, spectral and redox properties. The cis and trans isomers of di-p-benzidithiaoctaphyrin exhibit nonaromatic absorption features in the visible-NIR region, and electrochemical studies revealed their electron-rich nature. TD-DFT studies are in agreement with the experimental observations.

A small‐scale neutral alumina column chromatography method for carbon isotope determination of hopanes in crude oils or rock extracts

This paper presents a small-scale column chromatography method for separating hopanes in crude oil or rock extracts using neutral alumina as a solid phase adsorbent and a Pasteur pipette as a separation device. Three oil samples were selected to study the effect of solid phase adsorbent type and column length on the separation of hopanes. The oil samples were eluted with mixed reagents (V hexane: V petroleum ether = 8:2) and collected at intervals of 0.5 ml. Ten Fractions were collected and tested for the compounds using GC–MS. A quantitative approach was used to reveal distribution characteristics of compounds in each eluted Fraction. Experimental results showed that 100–200 um neutral alumina exhibited significant differences in the adsorptive capacity of biomarkers from oil samples and rock extracts. The elution order of the biomarkers in the chromatographic column (the length is 180 mm) was n-alkanes, steranes and hopanes. The separation of hopanes could be realized by collecting the eluted Fractions 4 and 5. Compared with the urea complexation, the purity of hopanes separated by column chromatography was higher. The concentration of n-alkanes (nC16-nC34) could be reduced from 1.99 to 4.83 mg/ml to 0.79–0.94 mg/ml, and the content of steranes can be reduced from the original 12% to 0.45%. Residual n-alkanes and steranes were not visible in the GC–MS detection. The Total Ion Chromatography (TIC) of hopanes was consistent with the distribution characteristics of the m/z191 mass chromatogram. The isolated hopanes could meet the detection requirements of isotope ratio mass spectrometry. The C29Ts/C29αβ ratio of hopanes decreased gradually from 1.63 to 0.73 as the column length increased. It is speculated that the variation of the C29Ts/C29αβ ratio is not only affected by maturity but also by the oil and gas migration. This method is a new attempt in the field of compound purification and can be widely used in the study of stable carbon isotopes of hopanes monomeric hydrocarbons.

Synthesis and Studies of Fused Benzo-Benzisapphyrins.

A series of rare examples of fused benzo-benzisapphyrins were synthesized readily by (3 + 2) condensation of benzodipyrrole-derived diol and para-benzitripyrrane in the presence of 0.5 equiv of TFA in CH2Cl2 under inert atmosphere conditions accompanied by DDQ oxidation in open air. The crude compounds were separated by basic alumina column chromatography and afforded pure fused benzo-benzisapphyrins in 20-22% yields. The fused sapphyrins were characterized in detail by high-resolution mass spectrometry (HRMS) and one-dimensional (1D) and two-dimensional (2D) NMR spectroscopy. The 1H NMR spectra recorded at both 298 and at 233 K clearly exhibited the presence of a strong diatropic ring current in benzo-benzisapphyrins, and the macrocycles are of aromatic nature. The DFT-optimized structure of benzo-benzisapphyrin revealed that the macrocycle was planar to a great extent due to the rigid structure of the dibenzopyrrole moiety, and the NICS(0) value of -11.2 ppm supports the aromatic nature of macrocycles. The absorption spectra of benzo-benzisapphyrins showed three weak Q bands approximately in the region of 650-900 nm and a strong Soret band at 480 nm, along with a shoulder band at ∼510 nm. The diprotonated derivative generated by the addition of excess TFA to the benzo-benzisapphyrin macrocycle exhibited bathochromically shifted absorption bands compared to the free base macrocycle.

Retention performance of alumina porous layer open-tubular column coated with γ–alumina nanoparticles in the highly volatile hydrocarbons separation

An alumina porous layer open-tubular (Al2O3 PLOT) column coated with γ–alumina nanoparticles (20 nm) for highly volatile hydrocarbons (C1 to C5) separation was described. Relative to the coating of bulk alumina, this column was easily coated with dynamic method under 0.4 or 0.6 MPa for 0.53 mm or 0.32 mm capillary, respectively. And the thickness of coating layer could be tuned by repeating the coating process after column was dried and activated at 300 °C for 3 h. The effect of deactivation agents on the physicochemical properties of nano γ–alumina was characterized by X–ray diffraction (XRD) measurement and nitrogen adsorption–desorption isotherms. The influences of deactivation agents, film thickness, conditioning and column dimensions on the inertness, polarity, selectivity and elution order of C1 to C5 separation were investigated in detail. The crystallite structure and size of nano alumina were not affected by the deactivation agents and remained constant during the column making processes, whereas specific surface area, pore volume and average half pore width altered significantly. The specific surface area decreased to 125.4 m2 g–1 or 174.0 m2 g–1 and the average half pore size distributions decreased to 1.6–8.4 nm or 2.4–14.3 nm when it was deactivated with potassium chloride or sodium sulfate solution, respectively. The deactivation agents and its concentrations impacted significantly on the retention performance of column. The column deactivated with sodium sulfate solution exhibited stronger polarity and lower selectivity than which deactivated with potassium chloride solution although both columns showed good inertness. The length, internal diameter and film thickness of the column had less influence on the selectivity and resolution for C1 to C5 hydrocarbons separation, whereas the conditioning temperature and time had an obvious influence. The column had distinguished polarity and selectivity which was different from either bulk or commercial alumina columns. Typically, the hydrocarbons were baseline separated with resolutions ranging from 1.65 to 15.33 within 9 min under programmed temperature below 100 °C, and the tailing factors ranging from 1.02 to 1.07.

Design a solid bed method for extraction, separation and analysis of polychlorinated biphenyl and hexachlorohexsane pollutants from soil/sediment samples

ABSTRACT Solid bed extraction technique as an efficient analytical method was exploited for developing a one step process of extraction and separation of organic pollutants; polychlorinated biphenyls and Hexachlorohexane, PCBs and HCH, respectively, from sediment/soil samples. The method was established using partition chromatography through 12% deactivated alumina column serially connected to 2% deactivated silica column. The extraction method was applied for the analysis of mixed standard PCB and HCH in different types of simulated contaminated samples; fortified sea sand and deutated soil samples. This method allows analysis of these contaminants in sediments at trace levels as low as 1.0 μg/g for PCBs and HCHs with a percent recovery range 98–120%. HCH was fully isolated from the PCBs using different eluent.

Preparation A Cross-Linked Copolymer By Using Unsaturated Poly(2-Butene Maleate) Polyester and Methyl Methacrylate

In this study, synthesis of unsaturated Poly(2-Butene Maleate) polyester by condensation polymerization and preparation of cross-linked graft copolymer with methyl methacrylate are presented. For this purpose, unsaturated polyesters were synthesized in four different time periods (12h, 24h, 36h, 48h) in the presence of hydroquinone using 1,4-Butanediol-2-ene and maleic anhydride. Then, the obtained unsaturated polyester was purified on the alumina column and used to obtain cross-linked copolymer with methyl methacrylate. Here in, methyl methacrylate acts as both co-monomer and cross-linking agent.
 In the preparation of Poly(2-Butene Maleate), the optimization study of the molecular weight and yield ratios with the time parameter was carried out. In the results obtained, it was observed that the maximum molecular weight was reached after almost 36 hours (Mn=3400). It was observed that time did not have much effect on the yield. Structural characterizations of the obtained products were supported by FT-IR and NMR analyzes. In thermal analysis, it was observed that the thermal stability of Cross-linked graft copolymer is higher than unsaturated polyester but lower than pure Poly(methyl methacrylate).

Rhenium Radioisotopes for Medicine, a Focus on Production and Applications.

In recent decades, the use of alpha; pure beta; or beta/gamma emitters in oncology, endocrinology, and interventional cardiology rheumatology, has proved to be an important alternative to the most common therapeutic regimens. Among radionuclides used for therapy in nuclear medicine, two rhenium radioisotopes are of particular relevance: rhenium-186 and rhenium-188. The first is routinely produced in nuclear reactors by direct neutron activation of rhenium-186 via 185Re(n,γ)186Re nuclear reaction. Rhenium-188 is produced by the decay of the parent tungsten-188. Separation of rhenium-188 is mainly performed using a chromatographic 188W/188Re generator in which tungsten-188 is adsorbed on the alumina column, similar to the 99Mo/99mTc generator system, and the radionuclide eluted in saline solution. The application of rhenium-186 and rhenium-188 depends on their specific activity. Rhenium-186 is produced in low specific activity and is mainly used for labeling particles or diphosphonates for bone pain palliation. Whereas, rhenium-188 of high specific activity can be used for labeling peptides or bioactive molecules. One of the advantages of rhenium is its chemical similarity with technetium. So, diagnostic technetium analogs labeled with radiorhenium can be developed for therapeutic applications. Clinical trials promoting the use of 186/188Re-radiopharmaceuticals is, in particular, are discussed.

Determination of 93Mo in Radioactive Samples of Sulfuric Acid Media from Nuclear Facilities.

93Mo is an important radionuclide in view of radioactive waste repository because of its long half-life and high mobility in the environment. 93Mo decays by electron capture without any measurable gamma ray emission. The concentration of 93Mo in most of the radioactive waste is many orders of magnitude lower than the major activation product radionuclides, which makes the accurate determination of 93Mo a big challenge. A new analytical method for the determination of 93Mo in sulfuric acid media from nuclear power reactor was developed. 93Mo was separated from most of the radionuclides by cation exchange chromatography followed by the removal of sulfate by CaSO4 precipitation. A further purification of 93Mo, especially from anion species of 51Cr and 125Sb, was achieved by anion exchange chromatography and a short alumina column separation. The chemical yield of 93Mo in the entire separation procedure reached about 75%, and the decontamination factors for all potential interfering radionuclides were 1.5 × 106-1.6 × 108. The purified 93Mo was measured by liquid scintillation counting through counting its low-energy Auger electrons. A detection limit of 2 mBq/g for 93Mo in 50 g sample was achieved by this method, which enables the quantitative determination of 93Mo in most of the radioactive samples in the decommissioning waste and coolant water of nuclear power reactors. The developed method has been successfully applied to determine 93Mo in coolant water of nuclear power reactors, providing a robust analytical approach of 93Mo for the radiological characterization of radioactive wastes.

Development of arsenic removal unit with electrocoagulation and activated alumina sorption: Field trial at rural West Bengal, India

In the present study, electrocoagulation (EC) with iron electrodes along with adsorption by activated alumina has been evaluated as a treatment process for arsenic removal from groundwater. Batch scale experiments were performed with iron electrodes to assess the removal efficiency of electrocoagulation. The effects of inter-electrode distance and electro-charge loading (ECL) were evaluated on arsenic removal. EC was able to decrease the arsenic concentration in the aqueous phase below 10 ppb at ECL of 60 coulomb/L with 1 cm inter-electrode distance. The optimal condition was obtained by Response Surface Methodology (RSM) with the help of central composite design (CCD). The regression equation and analysis of variance were originated using Design-Expert software and F value (131.56), p-value (<0.05), and desirability value of 1 were obtained for the optimized model. Activated alumina adsorption has also been shown to be a promising arsenic removal technology (As5+) with 15 min of equilibrium time. An arsenic removal system was designed with EC unit, sand filter, and activated alumina column in series for field application. The field unit was able to deliver safe water to the local community. During the operation, the electrodes were passivated, and calcium-based deposition was found on the cathodes. Periodic electrode reversal was able to minimise the passivation. Due to the accumulation of ferric hydroxide flocs, the pores of the filter bed become clogged and they must be cleaned by backwashing. The Backwash system should be continued until the water runs clear. An arrangement of a suitable soak pit is made to contain the backwash water avoiding any environmental contamination. EC could be able to deliver safe water locally in rural areas at affordable prices due to its high efficiency and low operation and maintenance costs.

Determination of polychlorinated naphthalenes in ambient air by isotope dilution gas chromatography-triple quadrupole mass spectrometry

环境空气中的多氯萘(PCNs)一般为痕量水平(pg/m3),要实现其准确定量必然对分析方法的提取、净化和仪器分析提出较高要求。研究通过考察提取溶剂种类、净化流程和色谱-质谱参数,建立了加速溶剂萃取(ASE)-多层硅胶复合中性氧化铝柱的净化方法,并利用同位素稀释气相色谱-三重四极杆质谱(GC-MS/MS)对环境空气中的多氯萘进行测定。同时,通过在采样、提取和进样分析前分别添加同位素内标,开展质量控制和保证。结果表明,在2~100 ng/mL范围内3~8氯萘的平均相对响应因子(RRF)的相对标准偏差(RSD)均小于16%。PCNs同类物的方法检出限为1~3 pg/m3(以样品体积为288 m3计算)。采用基质加标法评价了方法对环境空气样品中PCNs测定的精密度和准确度,低、中、高加标水平下3 ~8氯萘的平均加标回收率分别为89.0%~119.4%、98.6%~122.5%和93.7%~124.5%,测定结果的平均相对标准偏差分别为1.9%~7.0%、1.6%~6.6%和1.0%~4.8%。整个分析过程中,采样内标和提取内标的平均回收率分别为136.2%~146.0%和42.4%~78.1%, RSD分别为5.6%~7.5%和2.7%~17.5%,满足痕量分析的要求且平行性较好。方法的灵敏度和准确度高,精密度良好,适用于环境空气中3~8氯萘的准确定量测定,可在一定程度上缓解多氯萘监测对高分辨气相色谱-高分辨质谱的依赖,为实现多氯萘的国际履约提供方法支持。

Isoquinoline alkaloids from two species of Thalictrum genus plants

The chemical constituents from the roots of Thalictrum cultratum and T. baicalense were investigated. By various isolation methods, such as silica gel, aluminium oxide, ODS, and Sephadex LH-20 column chromatographies, and semi-preparative HPLC, 11 simple isoquinoline alkaloids were isolated from the ethanol extract of the roots of these two plants, including a new compound, named dehydrothalflavine(1), and ten known ones(2-11): N-methylcorydaline(2), N-methylthalidaldine(3), thaliflavine(4), oxyhydrastinine(5), noroxyhydrastinine(6), dimethoxyisoquinolone(7), thalactamine(8), dehydronoroxyhydrastinine(9), 6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroisoquinoline(10), and isopicnarrhine(11). Their structures were elucidated on the basis of HR-ESI-MS and 1 D and 2 D NMR techniques. Compound 1 was a new isoquinoline alkaloid. Compound 11 was obtained from Tha-lictrum plant for the first time. All compounds did not show cytotoxic activities against HL-60, U937, HCT116, Caco-2, and HepG2 cancer cell lines.

Tunable transmission near Dirac-like point in the designed plasma photonic crystal

The ingenious combination of gaseous plasma and alumina columns forms a plasma photonic crystal with the advantage of dynamic tunability to control the transmission of electromagnetic waves. Plasma density as another degree of freedom is used to realize the Dirac-like cone, which degenerates accidentally at the first Brillouin zone in a square lattice. The investigations of transmission spectrum and phase variation demonstrate that the Dirac-like cone formed in a plasma photonic crystal still possess the zero-refractive-index property, and the cloaking effect for obstacles can be turned on or off by adjusting the electron density. Based on the feature of dynamic tunability, the dual-channel optical switch is designed, and the transmission path of electromagnetic waves can be controlled dynamically.