Ultrasound assisted microextraction-nano material solid phase dispersion for extraction and determination of thymol and carvacrol in pharmaceutical samples: experimental design methodology

Solvent-Focused Gas Chromatographic Determination of Thymol and Carvacrol Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction through Solidifying Floating Organic Droplets (USA-DLLME-SFO)

An ultrasound-assisted dispersive liquid-liquid microextraction by solidifying floating organic droplets, coupled to a form of temperature-programmed gas chromatography flame ionization detection, has been developed for the extraction and determination of thymol and carvacrol. This method utilizes undecanol as the extraction solvent, offering advantages such as facilitating phase transfer through solidification and enhancing solvent-focusing efficiency. The optimal gas chromatography conditions include a sample injection volume of 0.2 µL, a split ratio of 1:10, and a flow rate of 0.7 mL min-1. The extraction conditions entail an extraction solvent volume of 20 µL, a disperser solvent (acetone) volume of 500 µL, pH 7.0, 7.0% NaCl (3.5 M), a sample volume of 5.0 mL, an ultrasound duration of 10 min, and a centrifuge time of 7.5 min (800 rpm). These conditions enable the achievement of a high and reasonable linear range of 3.5 to 70. 0 μg mL-1 for both thymol and carvacrol. The detection limits are found to be 0.95 and 0.89 μg mL-1, respectively, for thymol and carvacrol. The obtained relative standard deviations, 2.7% for thymol and 2.6% for carvacrol, demonstrate acceptable precision for the purpose of quantitative analysis.

Electrode Based on the MWCNTs and Electropolymerized Thymolphthalein for the Voltammetric Determination of Total Isopropylmethylphenols in Spices

Isopropylmethylphenols, namely thymol and carvacrol, are natural phenolic monoterpenoids with a wide spectrum of bioactivity making them applicable in the cosmetic, pharmaceutical, and food industry. The dose-dependent antioxidant properties of isopropylmethylphenols require their quantification in real samples. Glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNTs) and electropolymerized thymolphthalein has been developed for the sensitive quantification of isopropylmethylphenols. Conditions of thymolphthalein electropolymerization (monomer concentration, number of cycles, and electrolysis parameters) providing the best response to thymol have been found. Scanning electron microscopy and electrochemical methods confirm the effectivity of the electrode developed. The linear dynamic ranges of 0.050-25 and 25-100 µM for thymol and 0.10-10 and 10-100 µM for carvacrol with detection limits of 0.037 and 0.063 µM, respectively, have been achieved in differential pulse mode in Britton-Robinson buffer pH 2.0. The selectivity of the isopropylmethylphenols response in the presence of typical interferences (inorganic ions, saccharides, ascorbic acid) and other phenolics (caffeic, chlorogenic, gallic and rosmarinic acids, and quercetin) is a significant advantage over other electrochemical methods. The electrode has been used in the analysis of oregano and thyme spices. Total isopropylmethylphenols contents have been evaluated after a single sonication-assisted extraction with methanol.

Synthesis of a new magnetic metal organic framework based on nickel for extraction of carvacrol and thymol in thymus and savory samples and analyzed with gas chromatography

The present research aims at reporting a new sorbent, a magnetic nano scale metal-organic framework (MOF), based on nickel acetate and 6-phenyl-1,3,5-triazine-2,4-diamine. The prepared sorbent was used to extract carvacrol and thymol using an ultrasonic-assisted dispersive micro solid phase extraction (UA-DμSPE) method. The structure of the metal organic framework was studied by applying scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), energy dispersive spectrometry (EDS), and vibrating sample magnetometer (VSM). The effects of various parameters such as ionic strength of sample solution, amount of sorbent (mg), volume of eluent solvent (μL), vortex and ultrasonic times (min) were optimized. Under optimal conditions, the analytes resulted in determination coefficients (R ²) of 0.9985 and 0.9967 in the concentration range 0.01-2 μg mL^-1, and in limits of detection of 0.0025 and 0.0028 μg mL^-1. Significantly, this method can be successfully applied in order to determine the target analytes in spiked real samples. Notably, the relative mean recoveries range from 94.5 to 105.7%.

Highly effective pre-concentration of thymol and carvacrol using nano-sized magnetic molecularly imprinted polymer based on experimental design optimization and their trace determination in summer savoury, Origanum majorana and Origanum vulgare extracts

To ascertain thymol and carvacrol in pharmaceutical syrups, a valid and effective magnetic molecular imprinted polymer dispersive solid phase microextraction (MMIP-DSPME) process was developed in this study, which was in combination with a high performance liquid chromatography-ultra violet (HPLC-UV) technique for the assessment of thymol and carvacrol separation and pre-concentration. Contact time, eluent kind and volume, pH, the mass of the MMIP were all taken into consideration as key factors. Design expert and multi-objective response surface methodology (RSM) were used to optimize these variables. The mass of the MMIP, sample pH, eluent kind, time of sorption, the volume of eluent, and time of elution were 10 mg, 6, acetonitrile, 28 min, 200 µL, and 5.5 min, respectively, for the maximum extraction recovery of the analytes. The limit of detection (LOD) was 0.042 ng mL^-1 at the optimal conditions, while the value for the limit of quantification (LOQ) was 0.140 ng mL^-1. At the optimized conditions for thymol and carvacrol, the suggested MMIP sorbent had sorption capacities of 64.1 and 72.6 mg g^-1, respectively. Furthermore, for triplicate measurements, the linear dynamic range (LDR) was 0.40-5000 ng mL^-1, and the method's accuracy (RSD %) was 6.26%. The saturation magnetization for the MMIP was 19.0 emu g^-1 obtained by VSM, allowing the sorbent to be separated quickly. The sorption experiments confirmed the large sorption capacity of the MMIP for thymol and carvacrol, as well as its homogeneous binding sites. The extraction recovery for thymol and carvacrol was 96.9-103.8% and 96.6-105.4%, respectively, at all spiked amounts (20, 100, 200, and 500 ng mL^-1). The findings of seven desorption-regeneration cycles using MMIP demonstrated the high stability of the sorbent. The MMIP revealed a particular behavior of sorption for thymol and carvacrol, implying a selective, simple, effective, and flexible analytical method.

Sonochemical fabrication of inorganic nanoparticles for applications in catalysis

Catalysis covers almost all the chemical reactions or processes aiming for many applications. Sonochemistry has emerged in designing and developing the synthesis of nano-structured materials, and the latest progress mainly focuses on the synthetic strategies, product properties as well as catalytic applications. This current review simply presents the sonochemical effects under ultrasound irradiation, roughly describes the ultrasound-synthesized inorganic nano-materials, and highlights the sonochemistry applications in the inorganics-based catalysis processes including reduction, oxidation, degradation, polymerization, etc. Or all in all, the review hopes to provide an integrated understanding of sonochemistry, emphasize the great significance of ultrasound-assisted synthesis in structured materials as a unique strategy, and broaden the updated applications of ultrasound irradiation in the catalysis fields.

Ultrasound Assisted Dispersive Solid Phase Microextraction of Thymol and Carvacrol in Pharmaceutical Products Using Graphene Oxide as an Adsorbent Prior to Analysis by High Performance Liquid Chromatography

Background:

Thymol and carvacrol are the most important dietary constituents in thyme species. These two active compounds are used for the standardization of pharmaceutical compounds.

Objective:

In this work, a simple and reliable ultrasonic assisted dispersive solid phase microextraction method (USA-DSPME) coupled with high performance liquid chromatography-ultra violet detection system was developed to determine thymol and carvacrol in pharmaceutical syrups. The efficiency of SPME sorbent was examined through several sorbents and finally Graphene Oxide (GO) was applied for extraction of the analytes. Method: The efficiency of GO was compared with three reduced forms of GO adsorbents as well. Several effective factors on the extraction performance were investigated.

Results:

Under the optimized conditions for the GO sorbent, inter and intra-day relative standard deviations (RSDs, n = 3) and the Limits of Detections (LODs) were lower than 5.0% and 0.02 μg/ml, respectively. Moreover, good linear ranges were observed in wide concentration ranges with R-squared larger than 0.9961 for both thymol and carvacrol.

Conclusion:

The present method is reliable and simple for determination of carvacrol and thymol in pharmaceutical products.

Ultrasound combined with manganese-oxide nanoparticles loaded on activated carbon for extraction and pre-concentration of thymol and carvacrol in methanolic extracts of Thymus daenensis, Salvia officinalis, Stachys pilifera, Satureja khuzistanica, and mentha, and water samples

A dispersive micro solid-phase extraction (DMSPE) technique was developed using manganese-oxide nanoparticles loaded on activated carbon (Mn₃O₄-NPs-AC) as an effective sorbent combined with ultrasound for the extraction and determination of a trace amount of thymol and carvacrol in methanolic extracts of Thymus daenensis, Salvia officinalis, Stachys pilifera, Satureja khuzistanica and mentha, and water samples.

Synthesis and characterization of MIL-101(Cr) intercalated by polyaniline composite, doped with silica nanoparticles and its evaluation as an efficient solid-phase extraction sorbent

A metal-organic framework/polyaniline composite was synthesized and doped with silica nanoparticles. The structure and morphology of the composite were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. It was packed inside a cartridge and evaluated for the solid-phase extraction of thymol and carvacrol, followed by gas chromatography with flame ionization detection measurement. The influence of the important experimental variables on the efficiency of the proposed method, including pH, ionic strength, volume of sample solution and type, and volume of eluent were studied and optimized. Under the optimal conditions, the relative standard deviations were found to be 3.8 and 9.8% for thymol and carvacrol, respectively, and the corresponding limits of detection were 0.1 and 1.0 ng/mL. The linear dynamic ranges for the calibration curves of the analytes were 10-10000 ng/mL, with determination coefficients (R² ) > 0.993. The limits of quantifications were found to be 0.01 and 0.5 μg/mL, for thymol and carvacrol, respectively. The prepared nanocomposite sorbent was applied successfully to the extraction and determination of thymol and carvacrol in Lamiaceae plant extracts and a honey sample, with relative recoveries in the range of 90.28-122.0%.

Silver-choline chloride modified graphene oxide: Novel nano-bioelectrochemical sensor for celecoxib detection and CCD-RSM model

In this study, silver nanoparticles modified choline chloride functionalized graphene oxide (AgNPs-ChCl-GO) was synthesized using sonochemical method and utilized as a bioelectrochemical sensor for detection of celecoxib (CEL). The characterization studies were ultimately performed in order to acheive a more complete understanding of the morphological and structural features of the AgNPs-ChCl-GO using different techniques including FT-IR, AFM, FE-SEM, EDX, and XRD. AgNPs-ChCl-GO demonstrated a significant improvement in the reduction activity of CEL due to the enhancement in the current response compared to the bare carbon paste electrode (CPE). The optimum experimental conditions, were optimized using central composite design (CCD) methodology. The differential pulse voltammetry (DPVs) showed an expanded linear dynamic ranges of 9.6 × 10^-9-7.4 × 10^-7 M for celecoxib in Britton-Robinson buffer in pH 5.0 with. LOD (S/N = 3) and LOQ (S/N = 10) were obtained 2.51 × 10^-9 M and 6.58 × 10^-9 M respectively. AgNPs-ChCl-GO-carbon paste electrode exhibited suitable properties and high accuracy determination of celecoxib in the human plasma sample.

Ultrasound-accelerated synthesis of gold nanoparticles modified choline chloride functionalized graphene oxide as a novel sensitive bioelectrochemical sensor: Optimized meloxicam detection using CCD-RSM design and application for human plasma sample

In this research, gold nanoparticles modified choline chloride functionalized graphene oxide (AuNPs-ChCl-GO) was synthesized through the assistance of ultrasound and fabricated as a novel bioelectrochemical sensor and utilized for the sensitive detection of meloxicam (MEL). The morphological and structural features of the AuNPs-ChCl-GO were characterized using different techniques including FTIR, TEM, FE-SEM, EDX, and XRD. The modified electrode showed a remarkable improvement in the anodic oxidation activity of MEL due to the enhancement in the current response compared to the bare carbon paste electrode (CPE). The biosensor composition and measurement conditions were optimized using an experimental design. The differential pulse voltammetry (DPVs) exhibited expanded linear dynamic in the range of 9.0 × 10^-9 to 8.5 × 10^-7 M for MEL in Britton-Robinson buffer at pH = 4.0 with a detection limit of 1.008 × 10^-9 M. The practical utility of the modified electrode was demonstrated by the accurate detection of MEL in human plasma sample.

State of the art and recent advances in the ultrasound-assisted synthesis, exfoliation and functionalization of graphene derivatives

Sonochemistry, an almost a century old technique was predominantly employed in the cleaning and extraction processes but this tool has now slowly gained tremendous attention in the synthesis of nanoparticles (NPs) where particles of sub-micron have been produced with great stability. Following this, ultrasonication techniques have been largely employed in graphene synthesis and its dispersion in various solvents which would conventionally take days and offers poor yield. Ultrasonic irradiation allows the production of thin-layered graphene oxide (GO) and reduced graphene oxide (RGO) of up to 1nm thickness and can be produced in single layers. With ultrasonic treatment, reactions were made easy whereby graphite can be directly exfoliated to graphene layers. Oxidation to GO can also be carried out within minutes and reduction to RGO is possible without the use of any reducing agents. In addition, various geometry of graphene can be produced such as scrolled graphene, sponge or foam graphene, smooth as well as those with rough edges, each serving its own unique purpose in various applications such as supercapacitor, catalysis, biomedical, etc. In ultrasonic-assisted reaction, deposition of metal NPs on graphene was more homogeneous with custom-made patterns such as core-shell formation, discs, clusters and specific deposition at the edges of graphene sheets. Graphene derivatives with the aid of ultrasonication are the perfect catalyst for various organic reactions as well as an excellent adsorbent. Reactions which used to take hours and days were significantly reduced to minutes with exceedingly high yields. In a more recent approach, sonophotocatalysis was employed for the combined effect of sonication and photocatalysis of metal deposited graphene. The system was highly efficient in organic dye adsorption. This review provides detailed fundamental concepts of ultrasonochemistry for the synthesis of graphene, its dispersion, exfoliation as well as its functionalization, with great emphasis only based on recent publications. Necessary parameters of sonication such as frequency, power input, sonication time, type of sonication as well as temperature and dual-frequency sonication are discussed in great length to provide an overview of the resultant graphene products.

Ultrasound assisted extraction of Maxilon Red GRL dye from water samples using cobalt ferrite nanoparticles loaded on activated carbon as sorbent: Optimization and modeling

In this research, a selective, simple and rapid ultrasound assisted dispersive solid-phase micro-microextraction (UA-DSPME) was developed using cobalt ferrite nanoparticles loaded on activated carbon (CoFe₂O₄-NPs-AC) as an efficient sorbent for the preconcentration and determination of Maxilon Red GRL (MR-GRL) dye. The properties of sorbent are characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Vibrating sample magnetometers (VSM), Fourier transform infrared spectroscopy (FTIR), Particle size distribution (PSD) and Scanning Electron Microscope (SEM) techniques. The factors affecting on the determination of MR-GRL dye were investigated and optimized by central composite design (CCD) and artificial neural networks based on genetic algorithm (ANN-GA). CCD and ANN-GA were used for optimization. Using ANN-GA, optimum conditions were set at 6.70, 1.2mg, 5.5min and 174μL for pH, sorbent amount, sonication time and volume of eluent, respectively. Under the optimized conditions obtained from ANN-GA, the method exhibited a linear dynamic range of 30-3000ngmL^-1 with a detection limit of 5.70ngmL^-1. The preconcentration factor and enrichment factor were 57.47 and 93.54, respectively with relative standard deviations (RSDs) less than 4.0% (N=6). The interference effect of some ions and dyes was also investigated and the results show a good selectivity for this method. Finally, the method was successfully applied to the preconcentration and determination of Maxilon Red GRL in water and wastewater samples.

Pharmacological Properties and Molecular Mechanisms of Thymol: Prospects for Its Therapeutic Potential and Pharmaceutical Development

Thymol, chemically known as 2-isopropyl-5-methylphenol is a colorless crystalline monoterpene phenol. It is one of the most important dietary constituents in thyme species. For centuries, it has been used in traditional medicine and has been shown to possess various pharmacological properties including antioxidant, free radical scavenging, anti-inflammatory, analgesic, antispasmodic, antibacterial, antifungal, antiseptic and antitumor activities. The present article presents a detailed review of the scientific literature which reveals the pharmacological properties of thymol and its multiple therapeutic actions against various cardiovascular, neurological, rheumatological, gastrointestinal, metabolic and malignant diseases at both biochemical and molecular levels. The noteworthy effects of thymol are largely attributed to its anti-inflammatory (via inhibiting recruitment of cytokines and chemokines), antioxidant (via scavenging of free radicals, enhancing the endogenous enzymatic and non-enzymatic antioxidants and chelation of metal ions), antihyperlipidemic (via increasing the levels of high density lipoprotein cholesterol and decreasing the levels of low density lipoprotein cholesterol and low density lipoprotein cholesterol in the circulation and membrane stabilization) (via maintaining ionic homeostasis) effects. This review presents an overview of the current in vitro and in vivo data supporting thymol's therapeutic activity and the challenges concerning its use for prevention and its therapeutic value as a dietary supplement or as a pharmacological agent or as an adjuvant along with current therapeutic agents for the treatment of various diseases. It is one of the potential candidates of natural origin that has shown promising therapeutic potential, pharmacological properties and molecular mechanisms as well as pharmacokinetic properties for the pharmaceutical development of thymol.

Maghemite nanoparticle-decorated hollow fiber electromembrane extraction combined with dispersive liquid-liquid microextraction for determination of thymol from Carum copticum

BACKGROUND

A novel technique using maghemite nanoparticle-decorated hollow fibers to assist electromembrane extraction is proposed. Electromembrane extraction combined with dispersive liquid-liquid microextraction (EME-DLLME) was applied for the extraction of thymol from Carum copticum, followed by gas chromatography with flame ionization detection (GC-FID).

RESULTS

The use of maghemite nanoparticle-decorated hollow fibers was found to improve the extraction efficiency of thymol significantly. Important operational parameters, including pH of acceptor phase, extraction time, voltage and temperature, were investigated and optimized. At the optimal conditions, linearity in the range 4-1800 µg L^-1 with a determination coefficient of 0.9996 was obtained. The limit of detection was 0.11 µg L^-1 (S/N = 3) and the pre-concentration factor was 200. The intra- and inter-day precision was 5.9 and 2.2% respectively. The intra- and inter-day accuracy was higher than 93.6%.

CONCLUSION

The results indicated that EME-DLLME/GC-FID is a useful technique for the extraction and determination of thymol in C copticum. © 2016 Society of Chemical Industry.

Ultrasonic assisted dispersive solid-phase microextraction of Eriochrome Cyanine R from water sample on ultrasonically synthesized lead (II) dioxide nanoparticles loaded on activated carbon: Experimental design methodology

The present research focus on designing an appropriate dispersive solid-phase microextraction (UA-DSPME) for preconcentration and determination of Eriochrome Cyanine R (ECR) in aqueous solutions with aid of sonication using lead (II) dioxide nanoparticles loaded on activated carbon (PbO-NPs-AC). This material was fully identified with XRD and SEM. Influence of pH, amounts of sorbent, type and volume of eluent, and sonication time on response properties were investigated and optimized by central composite design (CCD) combined with surface response methodology using STATISTICA. Among different solvents, dimethyl sulfoxide (DMSO) was selected as an efficient eluent, which its combination by present nanoparticles and application of ultrasound waves led to enhancement in mass transfer. The predicted maximum extraction (100%) under the optimum conditions of the process variables viz. pH 4.5, eluent 200μL, adsorbent dosage 2.5mg and 5min sonication was close to the experimental value (99.50%). at optimum conditions some experimental features like wide 5-2000ngmL^-1 ECR, low detection limit (0.43ngmL^-1, S/N=3:1) and good repeatability and reproducibility (relative standard deviation, <5.5%, n=12) indicate versatility in successful applicability of present method for real sample analysis. Investigation of accuracy by spiking known concentration of ECR over 200-600ngmL^-1 gave mean recoveries from 94.850% to 101.42% under optimal conditions. The procedure was also applied for the pre-concentration and subsequent determination of ECR in tap and waste waters.

The choice of ultrasound assisted extraction coupled with spectrophotometric for rapid determination of gallic acid in water samples: Central composite design for optimization of process variables

A sensitive procedure namely ultrasound-assisted (UA) coupled dispersive nano solid-phase microextraction spectrophotometry (DNSPME-UV-Vis) was designed for preconcentration and subsequent determination of gallic acid (GA) from water samples, while the detailed of composition and morphology and also purity and structure of this new sorbent was identified by techniques like field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and Energy-dispersive X-ray spectroscopy (EDX) techniques. Among conventional parameters viz. pH, amount of sorbent, sonication time and volume of elution solvent based on Response Surface Methodology (RSM) and central composite design according to statistics based contour the best operational conditions was set at pH of 2.0; 1.5mg sorbent, 4.0min sonication and 150μL ethanol. Under these pre-qualified conditions the method has linear response over wide concentration range of 15-6000ngmL^-1 with a correlation coefficient of 0.9996. The good figure of merits like acceptable LOD (S/N=3) and LOQ (S/N=10) with numerical value of 2.923 and 9.744ngmL^-1, respectively and relative recovery between 95.54 and 100.02% show the applicability and efficiency of this method for real samples analysis with RSDs below 6.0%. Finally the method with good performance were used for monitoring under study analyte in various real samples like tap, river and mineral waters.

Ultrasound assisted combined molecularly imprinted polymer for selective extraction of nicotinamide in human urine and milk samples: Spectrophotometric determination and optimization study

Ultrasound-assisted dispersive solid phase microextraction followed by UV-vis spectrophotometer (UA-DSPME-UV-vis) was designed for extraction and preconcentration of nicotinamide (vitamin B₃) by HKUST-1 metal organic framework (MOF) based molecularly imprinted polymer (MIP). This new material was characterized by FTIR and FE-SEM techniques. The preliminary Plackett-Burman design was used for screening and subsequently the central composite design justifies significant terms and possible construction of mathematical equation which give the individual and cooperative contribution of variables like HKUST-1-MOF-NA-MIP mass, sonication time, temperature, eluent volume, pH and vortex time. Accordingly the optimum condition was set as: 2.0mg HKUST-1-MOF-NA-MIP, 200μL eluent and 5.0min sonication time in center points other variables were determined as the best conditions to reach the maximum recovery of the analyte. The UA-DSPME-UV-vis method performances like excellent linearity (LR), limits of detection (LOD), limits of quantification of 10-5000μgL^-1 with R² of 0.99, LOD (1.96ngmL^-1), LOQ (6.53μgL^-1), respectively show successful and accurate applicability of the present method for monitoring analytes with within- and between-day precision of 0.96-3.38%. The average absolute recoveries of the nicotinamide extracted from the urine, milk and water samples were 95.85-101.27%.

Trace determination of safranin O dye using ultrasound assisted dispersive solid-phase micro extraction: Artificial neural network-genetic algorithm and response surface methodology

In this study, ultrasound assisted dispersive solid-phase micro extraction combined with spectrophotometry (USA-DSPME-UV) method based on activated carbon modified with Fe2O3 nanoparticles (Fe2O3-NPs-AC) was developed for pre-concentration and determination of safranin O (SO). It is known that the efficiency of USA-DSPME-UV method may be affected by pH, amount of adsorbent, ultrasound time and eluent volume and the extent and magnitude of their contribution on response (in term of main and interaction part) was studied by using central composite design (CCD) and artificial neural network-genetic algorithms (ANN-GA). Accordingly by adjustment of experimental conditions suggested by ANN-GA at pH 6.5, 1.1mg of adsorbent, 10min ultrasound and 150μL of eluent volume led to achievement of best operation performance like low LOD (6.3ngmL(-1)) and LOQ (17.5ngmL(-1)) in the range of 25-3500ngmL(-1). In following stage, the SO content in real water and wastewater samples with recoveries between 93.27-99.41% with RSD lower than 3% was successfully determined.

Dispersion of hydrophobic magnetic nanoparticles using ultarsonic-assisted in combination with coacervative microextraction for the simultaneous preconcentration and determination of tricyclic antidepressant drugs in biological fluids

A two-step sample preparation technique based on dispersive micro solid-phase extraction combined with coacervative microextraction is presented for preconcentration and determination of tricyclic antidepressant drugs in biological samples. An important feature of the method is the application of hydrophobic magnetic nanoparticles, which in combination with coacervative microextraction method enables development of rapid and efficient extraction procedure in order to achievement of a high extraction efficiency. Simultaneous optimization by experimental design lead to improvement of method with low cost which supply useful information about interaction among variables. Under the optimized conditions, a linear range of 5-1000ngmL(-1) with detection limits from 0.51 to 1.4ngmL(-1) were obtained for target analytes. The method was successfully used for the determination of analytes in biological fluids (plasma and urine) with relative recoveries in the range of 89-105% (RSDs<3.5%).

Highly efficient simultaneous ultrasonic-assisted adsorption of Pb(II), Cd(II), Ni(II) and Cu (II) ions from aqueous solutions by graphene oxide modified with 2,2'-dipyridylamine: Central composite design optimization

In present work, a graphene oxide chemically modified with 2,2'-dipyridylamine (GO-DPA), was synthesized by simple, fast and low-cost process for the simultaneous adsorption of four toxic heavy metals, Pb(II), Cd(II), Ni(II) and Cu(II), from aqueous solutions. The synthesized adsorbent was characterized by FT-IR, XRD, XPS, SEM and AFM measurements. The effects of variables such as pH solution, initial ion concentrations, adsorbent dosage and sonicating time were investigated on adsorption efficiency by rotatable central composite design. The optimum conditions, specified as 8mg of adsorbent, 20mgL(-1) of each ion at pH 5 and short time of 4min led to the achievement of a high adsorption capacities. Ultrasonic power had important role in shortening the adsorption time of ions by enhancing the dispersion of adsorbent in solution. The adsorption kinetic studies and equilibrium isotherms for evaluating the mechanism of adsorption process showed a good fit to the pseudo-second order and Langmuir model, respectively. The maximum adsorption capacities (Qm) of this adsorbent were 369.749, 257.201, 180.893 and 358.824mgg(-1) for lead, cadmium, nickel and copper ions, respectively. The removal performance of adsorbent on the real wastewater samples also showed the feasibility of adsorbent for applying in industrial purposes.

Magnetic nanoparticle based dispersive micro-solid-phase extraction for the determination of malachite green in water samples: optimized experimental design

This paper presents an extraction method based on dispersive-nanoparticle-solid phase microextraction for the preliminary preconcentration and subsequent spectrophotometric determination of trace amounts of malachite green.