Determination of Prometryne in water and soil by HPLC-UV using cloud-point extraction

A CPE-HPLC (UV) method has been developed for the determination of Prometryne. In this method, non-ionic surfactant Triton X-114 was first used to extract and pre-concentrate Prometryne from water and soil samples. The separation and determination of Prometryne were then carried out in an HPLC-UV system with isocratic elution using a detector set at 254 nm wavelength. The parameters and variables that affected the extraction were also investigated and the optimal conditions were found to be 0.5% of Triton X-114 (w/v), 3% of NaCl (w/v) and heat-assisted at 50 °C for 30 min. Using these conditions, the recovery rates of Prometryne ranged from 92.84% to 99.23% in water and 85.48% to 93.67% in soil, respectively, with all the relative standard deviations less than 3.05%. Limit of detection (LOD) and limit of quantification (LOQ) were 3.5 μg L⁻¹ and 11.0 μg L⁻¹ in water and 4.0 μg kg⁻¹ and 13.0 μg kg⁻¹ in soil, respectively. Thus, we developed a method that has proven to be an efficient, green, rapid and inexpensive approach for extraction and determination of Prometryne from soil samples.     

Comparison of traditional cloud-point extraction and on-line flow-injection cloud-point extraction with a chemiluminescence method using benzo[a]pyrene as a marker

In this work, using benzo(a)pyrene (BaP) as marker, the analytical merits of on-line flow-injection cloud-point extraction (FI CPE), including preconcentration factor, extraction efficiency, sample throughput, and analysis time were evaluated by use of peroxyoxalate chemiluminescence (CL) detection. Moreover, by detailed discussion of several preconcentration conditions for traditional and on-line FI CPE the advantages of on-line FI CPE became conspicuously apparent. When coupled with separation techniques such as high-performance liquid chromatography (HPLC) or capillary electrophoresis (CE), on-line FI CPE–CL has much potential for analysis of low concentrations of polycyclic aromatic hydrocarbons (PAH) in environmental samples.     

Analysis of meloxicam by high-performance liquid chromatography with cloud-point extraction

A simple cloud-point extraction method for the determination of meloxicam in human serum was developed. Meloxicam was extracted from serum sample after adding 1 mL of 3% (v/v) Triton X-114 aqueous solution in the presence of 1M HCl and 60 mg NaCl. The meloxicam, present in the surfactant-rich phase, was enriched again with acetonitrile. Tenoxicam was used as the external standard. The separation was achieved on a C18 analytical column with a mobile phase consisting of aqueous acetic acid (1%, v/v) and acetonitrile (54:46, v/v). UV detection was performed at 360 nm. The response was linear over the range 45–2000 ng mL⁻¹ in human serum, and intra- and interday precisions of less than 15.0% were obtained. The relative error was within ±3.0%. The recoveries of meloxicam were larger than 92.0%. The method was compared with liquid–liquid extraction. The results showed that the new method has a considerable LOQ and higher recoveries but poorer precision than liquid–liquid extraction, which exhibited poor recoveries of less than 86.0%, precisions of less than 5.0% and relative errors of less than 7.0%. The method was used for the determination of meloxicam in healthy human volunteers.     

多维离子交换色谱分离和串联质谱鉴定在小鼠肝脏膜蛋白质组分析中的应用

膜蛋白质在变性剂作用下能够较充分地溶解。根据这一特点,我们试图在变性剂溶液中采用串联离子交换色谱法分离小鼠肝脏膜蛋白质。将小鼠肝脏膜蛋白质溶解于含有4 mol/L尿素,20 mmol/L三羟甲基氨基甲烷(Tris)-盐酸缓冲液(pH 9.0)中,用Q-Sepharose FF和Sephacryl S-200HR树脂组成的色谱柱结合大部分溶解的膜蛋白质,然后采用氯化钠线性梯度洗脱蛋白质,分步收集后采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)进一步分离洗脱组分的蛋白质。利用胶内胰蛋白酶消化技术将SDS-PAGE胶内分离的蛋白质降解为相应的肽段,然后以反相高效液相色谱分离和离子阱质谱仪鉴定肽段。根据文献报道和蛋白质的功能分类,在所鉴定的392个蛋白质中有306个可能为膜蛋白质或膜结合蛋白质。蛋白质的疏水性计算表明,GRAVY(grand average of hydropathicity)得分大于或等于0.00的蛋白质有83个。综上所述,我们有理由认为本实验方法基本符合小鼠肝脏膜蛋白质组学研究的要求。     

Determination of osthole in rat plasma by high-performance liquid chromatograph using cloud-point extraction

A new straightforward method based on cloud-point extraction (CPE) was developed to determine osthole in rat plasma by reversed phase high-performance liquid chromatography with ultraviolet detection using a photodiode array detector. The non-ionic surfactant Triton X-114 was chosen as the extract solvent. Variable parameters affecting the CPE efficiency were evaluated and optimized. A Zorbax SB-C₁₈ column was used for elution separation at 25 °C with detection wavelength at 322 nm. Under the optimum conditions, the method was shown to be reproducible and reliable with intra-day precision below 7.62%, inter-day precision below 6.37%, and accuracy within ±5.02% and mean extraction recovery more than 90.4%, which were all calculated using a range of spiked samples at three concentrations of 0.5, 5.0 and 15.0 μg mL⁻¹ for osthole in plasma. The calibration curve for the analyte was linear in the range from 0.1 to 20 μg mL⁻¹ with the correlation coefficients greater than 0.9981. Limit of detection (S/N = 3) was less than 0.03 μg mL⁻¹and limit of quantification (S/N = 10) was less than 0.1 μg mL⁻¹. After strict validation, the method was successfully applied to the pharmacokinetic study of osthole in rats after oral and intravenous administration, respectively.     

Development and application of high-performance liquid chromatography for the study of ampelopsin pharmacokinetics in rat plasma using cloud-point extraction

A simple, rapid and specific method based on cloud-point extraction (CPE) was developed to determine ampelopsin in rat plasma after oral administration by reversed-phase high-performance liquid chromatography. The non-ionic surfactant Genapol X-080 was chosen as the extract solvent. Some important parameters affecting the CPE efficiency, such as the nature and concentration of surfactant, extraction temperature and time, centrifuge time and salt effect, were investigated and optimized. Separation was accomplished using a C(18) column by gradient elution with a acetonitrile-phosphate buffer solution as the mobile phase. The detection wavelength was set at 290 nm. Under optimum conditions, the linear range of ampelopsin in rat plasma was 20-2000 ng/mL (r(2)=0.9996). The limit of detection was 6 ng/mL (S/N=3) with the limit of quantification being 20 ng/mL (S/N=10). The proposed method has been successfully applied for pharmacokinetic studies of ampelopsin from rat plasma after oral administration.     

Preconcentration of hydrophilic pesticides from aqueous solutions and extraction of residues using the polymeric sorbent Wofatit Y 77

Summary The new organic polymeric sorbent Y 77, exhibiting a specific surface of > 1200 m²/g and a capacity 5 mg/g reveals recoveries of > 90% for compounds of high water solubility following adsorption from water or saturated NaCl-solution and elution with methanol. Examples are given for the ³²P- or ¹⁴C-labelled insecticides methamidophos, trichlorfon and dimethoate and the herbicides Na-trichloroacetate, fenuron, propachlor and 2,4-D. For the more strongly adsorbed hydrophobic compounds the elution by hot solvents is recommended. The hydrophilic metabolites occurring in pesticide metabolism studies, e.g. conjugates, can be adsorbed and separated from the not adsorbed free carbohydrates.

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Anreicherung hydrophiler Pesticide aus wä\rigen Lösungen und Extraktion von Rückständen mit dem Polymer-Adsorber Wofatit Y77I. Anreicherung hydrophiler Pesticide aus Wasser

     

Use of surfactant-mediated phase separation (cloud point extraction) with affinity ligands for the extraction of hydrophilic proteins

The feasibility of utilizing a zwitterionic surfactant, 3-(nonyldimethylammonio)propylsulfate, or nonionic surfactant, Triton X-114, mediated phase separation in conjunction with affinity ligands was studied for hydrophilic protein extractions. Below (or above) its critical temperature (so-called cloud point), aqueous solutions of zwitterionic (or nonionic) surfactants separate into two immiscible phases, a surfactant-rich phase and an aqueous phase. Avidin was successfully extracted into the zwitterionic surfactant-rich phase when a small amount of the affinity ligand, N- biotinoyl)dipalmitoyl- l -alpha- phosphatidyl ethanolamine, was added to the system. It was not possible to extract hexokinase into the surfactant-rich phase of the nonionic surfactant, Triton X-114, even if a considerable amount of octyl-beta-d-glucoside was added to the solution as an affinity ligand. In contrast, the use of the zwitterionic surfactant and octyl-beta-d-glucoside as an affinity ligand proved to be effective for the extraction of hexokinase. The hexokinase extraction efficiency was found to depend upon the solution pH and the concentration of the affinity ligand in the system. The results clearly indicate that hydrophilic proteins can be successfully extracted with surfactant mediated phase separations (cloud point extractions) via use of the zwitterionic surfactant, 3-(nonyldimethylammonio)propylsulfate, and appropriate affinity ligands. Some advantages of zwitterionic surfactants in such extractive processes relative to that of nonionic surfactants are delineated.     

Non-dispersive extraction separation of metals using hydrophilic microporous and cation exchange membranes

Non-dispersive extraction of Zn(II) and Cu(II) from single and binary solutions across a flat-sheet membrane to an organic solution containing di(2-ethylhexyl)phosphoric acid (D2EHPA) was studied. Hydrophilic microporous and cation exchange membranes were used. Experiments were performed as a function of the pH (2–6), metal concentration (0.31–3.13 mol/m³), and D2EHPA concentration (50–500 mol/m³). It was shown that the presence of one metal retarded the transport of the other. Compared to the hydrophilic microporous membrane, the cation exchange membrane gave a low extraction rate of both metals in either single or binary systems, but gave a higher selectivity of Zn(II) over Cu(II) in binary systems at high D2EHPA concentrations.     

Preconcentration of hydrophilic and hydrophobic pesticides from aqueous solutions and extraction of residues using the polymeric sorbent Wofatit Y 77

Summary Preconcentration of hydrophilic pesticides has been reported (Fresenius Z. Anal. Chem. 1987, 328:484–486) of the insecticides methamidophos, trichlorfon, dimethoate and the herbicides Na-trichloroacetate, fenuron, propachlor and 2,4-D. Meanwhile, the following compounds have been included into the experiments: dimethoxon, methylparathion, bromophos, DDT, bromuron and lenacil from water in the concentration range between 0.05 g/l and 1.0 mg/l; dimethoate and methamidophos from fruits and vegetables in the range of 0.1 mg/kg and dimethoate, propachlor and 2,4-D and a series of triazine, carbamate and urea herbicides from soils in the range of 0.2 to 1.0 mg/kg. The adsorption of dissociated compounds by Wofatit Y 77, depending on the pH intervals investigated, was effective for some compounds, but ineffective for ethephon, glyphosate, CCC and amitrole. Extraction of plant material using NaCl solution yielded recoveries of 65–95% of dimethoate, but for methamidophos bound residues causing reduced recoveries have been observed. Optimal recoveries have been attained for extracting soils and sediments by mixtures of methanol or acetone with water. Studies were performed by using radiolabelled compounds and TLC, whereas GC was effective for selected samples only, depending also on the type of detector used, what has to be studied in further experiments.Proposed nomenclature of Wofatit Y 77 later to be used: Wofatit EP 63 Part I: see [5]     

Determination of disulfoton in surface water samples by cloud-point extraction and gas chromatography

This article proposes an alternative method, using cloud-point extraction and gas chromatography, for extraction and determination of disulfoton in water samples. For cloud-point extraction, the nonionic surfactant Triton X-114 was used. Before gas chromatography, a cleanup stage for surfactant removal from the extracts was optimized. Cleanup used two columns, in series, containing silica gel and Florisil, with methanol:hexane (1?:?1) as eluent, resulting in the removal of more than 95% of the Triton X-114. Factors such as ionic strength (>0.5?mol?L^?1) and surfactant concentration (1.0% w/v) increased the extraction efficiency of the cloud-point methodology, yielding disulfoton recoveries of almost 100%. Compared with liquid–liquid extraction, the cloud-point methodology was more efficient, with a better detectability, and resulted in a significant reduction in solvent volume.     

Modulation of Tenoxicam release from hydrophilic matrix: modulator membrane versus rate-controlling membrane

This paper describes the preparation of two layered device comprising of tenoxicam containing layer and a drug free membrane layer based on Geomatrix Technology. Our device based on bilaminated films which produced by a casting/solvent evaporation technique. The drug-hydroxypropyl methylcellulose (HPMC) layer was covered by drug free membrane layer composed of a mixture of different ratios of HPMC and ethyl cellulose (EC). The prepared devices were evaluated for thickness, weight, drug content uniformity, water absorption capacity and in-vitro drug release. The films were also evaluated for appearance, smoothness and transparency. The influence of drug free membrane layer composition and thickness on the drug release pattern was studied on 12 devices (D1 to D12). The results indicate that, the release of drug from HPMC matrixes without the drug free membrane layer was fast and follows diffusion controlled mechanism. The release of drug from the devices D1, D4, D9 and D12 follow the same mechanism, while the release of drug from other devices become linear with time (zero order) and extended for long time especially when thickness and the ratio of EC was increased in the drug free membrane layer. From this study it is concluded that, changing the geometry of drug layer by addition of drug free membrane layer and changing its composition and thickness plays an important role in determining whether the drug free membrane layer is rate-controlling or modulator membrane. Hence it can facilitate the development of different pharmaceutical products with different release pattern.     

Simultaneous cloud-point extraction of nine cations from water samples and their determination by flame atomic absorption spectrometry.

The cloud-point methodology was successfully employed for the preconcentration of heavy metal cations at trace levels from aqueous samples prior to flame atomic absorption spectrometry (FAAS). Cations were taken into a complex with 8-quinolinol in an aqueous non-ionic surfactant, Triton X-114, medium and concentrated in the surfactant rich phase by bringing the solution to the cloud-point temperature. The preconcentration of only 100 mL of the solution with 1% Triton X-114 and 10(-3) M 8-quinolinol at pH 7.0 gave a preconcentration factor higher than 100 for most cations. Under these conditions, the detection limits of the cloud-point extraction-FAAS system were 0.8 - 15 microg/L.     

Multivariate optimization of a procedure for Cr and Co ultratrace determination in vegetal samples using GF AAS after cloud-point extraction

Abstract

Sediment cores were collected at the MOLAR (MOuntain LAke Research) site Jörisee. The goal of the analysis was to date the sediment cores in order to correlate actual input conditions of nutrients and pollutants at this high-alpine, remote site, to historical situations. The sediment cores were dated by determining gamma rays of Pb-210 and Cs-137. The calculated sedimentation rate is 0.1 cm/year. Leaching techniques were used to investigate redox sensitive species. The results give evidence for post depositional recycling in case of Fe and Mn. In contrast, the heavy metals Pb, Zn, Cr and Ni are not affected by existing redox gradients. Sediment samples were leached with diluted nitric acid to determine anthropogenic input of Pb, Zn, Cr and Ni. Concentrations of these heavy metals reflect changes in the input conditions since the beginning of industrialization, which is the examined time period.     

Micelle-mediated extraction and cloud-point preconcentration of osthole and imperatorin from Cnidium monnieri with analysis by high performance liquid chromatography

A new method based on micelle-mediated extraction and cloud-point preconcentration was developed for the separation and determination of hydrophobic compounds osthole and imperatorin from Cnidium monnieri by high performance liquid chromatography with photodiode array detection. The non-ionic surfactant C(13)E(8) (Genapol X-080) was chosen as the extract solvent. Various experimental conditions were investigated to evaluate and optimize the extraction and preconcentration process. The chromatographic separation was accomplished on a Zorbax SB-C(18) analytical column (150 mm x 4.6mm i.d., 5 microm particle diameter) maintained at 30 degrees C and detected by UV absorption at 320 nm. The gradient elution was achieved with a mobile phase composed of 0.1% phosphoric acid and acetonitrile at a flow rate of 1.0 mL min(-1). Under the optimum conditions, the calibration curve for both analytes was linear in the range of 0.52-33.5 microg mL(-1) with the correlation coefficients greater than 0.9996. The intra-day and inter-day precision (RSD) is below 5.3% and the limits of detection (LOD) for the analytes are 93 and 124 ng mL(-1)(S/N=3). The proposed technique is a low cost, simple and sensitive method with high clean-up effect. Finally, the method was successfully applied to separate and determine osthole and imperatorin from C. monnieri, respectively.     

Microwave-assisted synthesis of biofunctional and fluorescent silicon nanoparticles using proteins as hydrophilic ligands

Protective shell: A microwave-assisted method allows rapid production of biofunctional and fluorescent silicon nanoparticles (SiNPs), which can be used for cell labeling. Such SiNPs feature excellent aqueous dispersibility, are strongly fluorescent, storable, photostable, stable at different pH values, and biocompatible. The method opens new avenues for designing multifunctional SiNPs and related silicon nanostructures.     

Rapid, highly efficient extraction and purification of membrane proteins using a microfluidic continuous-flow based aqueous two-phase system

Membrane proteins play essential roles in regulating various fundamental cellular functions. To investigate membrane proteins, extraction and purification are usually prerequisite steps. Here, we demonstrated a microfluidic aqueous PEG/detergent two-phase system for the purification of membrane proteins from crude cell extract, which replaced the conventional discontinuous agitation method with continuous extraction in laminar flows, resulting in significantly increased extraction speed and efficiency. To evaluate this system, different separation and detection methods were used to identify the purified proteins, such as capillary electrophoresis, SDS-PAGE and nano-HPLC-MS/MS. Swiss-Prot database with Mascot search engine was used to search for membrane proteins from random selected bands of SDS-PAGE. Results indicated that efficient purification of membrane proteins can be achieved within 5-7s and approximately 90% of the purified proteins were membrane proteins (the highest extraction efficiency reported up to date), including membrane-associated proteins and integral membrane proteins with multiple transmembrane domains. Compared to conventional approaches, this new method had advantages of greater specific surface area, minimal emulsification, reduced sample consumption and analysis time. We expect the developed method to be potentially useful in membrane protein purifications, facilitating the investigation of membrane proteomics.     

Acid-induced cloud-point extraction coupled to spectrophotometry for the determination of carbaryl residues in waters and vegetables

A simple and rapid spectrophotometry for the determination of carbaryl based on acid-induced anionic surfactant micelle-mediated extraction (acid-induced cloud-point extraction) coupled to derivatization with 2-naphthylamine-1-sulfonic acid (ANSA) reagent has been demonstrated. Sodium dodecyl sulfate (SDS) and concentrated HCl were used as extractants at room temperature. ANSA derivatization was directly reacted with carbaryl without alkali hydrolysis. The optimum conditions for both acid-induced extraction and derivatization were investigated. The proposed method shows good analytical features with low detection limit (50 µg L^− 1) as well as linearity covered a wide range up to 7.0 mg L^− 1, good precision with the relative standard deviation of 2.3% (n = 10), and high recoveries in the samples (> 85%). The high risks of carbaryl contamination in the local vegetable samples studied were observed with the level of 2.2 g kg^− 1. The results of the proposed method were comparable to those obtained from HPLC (t-test, P = 0.05).