Cloud Point Extraction Procedure Research Articles

Application of ultrasonically modified cloud point extraction method for simultaneous enrichment of cadmium and lead in sera of different types of gallstone patients

A novel and greener ultrasonically assisted/modified cloud point extraction procedure for the simultaneous preconcentration of lead and cadmium in serum samples of different types of gallstone patients was developed. The chelates of the under study metals, formerly formed with 8-hydroxyquinoline, were extracted in the micelles of a nonionic surfactant prior to analysis by flame atomic absorption spectrometer (FAAS). After the arrival of the cloud point, the critical micellar mass produced was homogenously dispersed in the aqueous phase with the help of ultrasound energy. The reliability of the developed procedure was tested by relative standard deviation (% RSD), which was found to be <5%. The performance of the proposed procedure was checked by applying to certified reference material and spiking standard in real samples. All the experimental parameters were optimized. The developed procedure of Um-CPE was applied successfully for the analysis of the target heavy metals in serum samples of different types of gallstone patients and referents. The higher levels of the understudy metals were observed in the patients as compared to the referents but the levels of the both metal were found to be considerably higher in patients with pigmented gallstones.

A New Ultrasonic Assisted Cloud Point Extraction and Preconcentration Procedure for the Spectrophotometric Oxalate Determination in Beverages

A New Ultrasonic Assisted Cloud Point Extraction and Preconcentration Procedure for the Spectrophotometric Oxalate Determination in Beverages

Air-Agitated Cloud-Point Extraction Coupled with High-Performance Liquid Chromatography for Determination of Heterocyclic Aromatic Amines in Smoked Sausages

An air-agitated cloud-point extraction procedure (AACPE), which is a new generation of cloud-point extraction procedure, has been investigated for extraction and preconcentration of four heterocyclic amines (i.e., 2-Amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline (MeIQ), 2-Amino-3,4,8-trimethyl-3H-imidazo[4,5-f]quinoxaline (4,8-DiMeIQx), 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), and 1-methyl-9H-pyrido[3,4-B]indole (harmane)) prior to high-performance liquid chromatography (HPLC). In order to enhance the extraction efficiency, the mixture of the aqueous sample solution and extraction solvent (Triton X-114) was repeatedly aspirated and dispensed using a syringe. Various parameters affecting the extraction efficiency of the AACPE procedure, including type and amount of salt, concentration of Triton X-114, extraction time (or number of air agitations), and centrifugation time, were investigated. No temperature controller was necessary. Under the optimum extraction condition, the linearity was achieved between 0.005 and 1.00 mg kg−1 with the correlation coefficient (R 2) > 0.999. The low limit of detections (LODs) ranged from 0.001 to 0.003 mg kg−1 with high enrichment factor (EF) more than 80. Matrix-matched calibration has been used for analysis of the target analytes in real samples. The applicability of the developed procedure was successfully evaluated by the determination of the heterocyclic amines in smoked sausage samples.

Optimization of a cloud point extraction procedure with response surface methodology for the quantification of dissolved iron in produced water from the petroleum industry using FAAS

The characterization of inorganic elements in the produced water (PW) samples is a difficult task because of the complexity of the matrix. This work deals with a study of a methodology for dissolved Fe quantification in PW from oil industry by flame atomic absorption spectrometry (FAAS) after cloud point extraction (CPE). The procedure is based on the CPE using PAN as complexing agent and Triton X-114 as surfactant. The best conditions for Fe extraction parameters were studied using a Box-Behnken design. The proposed method presented a LOQ of 0.010μgmL−1 and LOD of 0.003μgmL−1. The precision of the method was evaluated in terms of repeatability, obtaining a coefficient of variation of 2.54%. The accuracy of the method was assessed by recovery experiments of Fe spiked that presented recovery of 103.28%. The method was applied with satisfactory performance to determine Fe by FAAS in PW samples.

Determination of Nano Amounts of Copper in Environmental, Biological, and Water Samples Via Cloud Point Extraction and Spectrophotometry

A cloud point extraction procedure was presented for the preconcentration and determination of copper(II) ion in various real samples. After complexation by amino-4-(3-nitrophenylazo)pyridine-3-ol, (ANPAP), copper(II) ions was quantitatively recovered in Triton X-114 after centrifugation. 0.4 mL of ethanol acidified with 1.0 M HNO3 was added to the surfactant-rich phase prior to its analysis by specrophotometry at λmax 618. The influence of analytical parameters including complexing agent, Triton X-114, buffer solutions, bath temperature, heating time, centrifuge rate and time were optimized. Under the optimum conditions, the calibration curve is linear for the concentration range of 4.0-115 ng mL-1. The detection and quantification limits of the method were 1.20 and 3.94 ng mL-1 of Cu(II) ion. The enhancement factor of 250 was achieved for 100 mL samples containing the analyte with RSDs were 31.25%. The interference effect of some anions and cations was also tested. The method was applied to determine of copper in environmental, water and biological samples.

Evaluation of Mercury Concentrations in Groundwater Samples of Coal Field Using a Matrix-less Cloud Point Extraction Procedure Prior to Analysis by Cold Vapor Atomic Absorption Spectrometry

Evaluation of Mercury Concentrations in Groundwater Samples of Coal Field Using a Matrix-less Cloud Point Extraction Procedure Prior to Analysis by Cold Vapor Atomic Absorption Spectrometry

Green technology for monitoring the quality of water: determination of toxic trace analyte concentrations using multielemental mixed micelle cloud point extraction

AbstractA simple multielemental mixed micelle cloud point extraction procedure has been developed for the simultaneous separation and preconcentration of toxic trace analytes from natural and wastewater samples prior to their determination by electrothermal atomic absorption spectrometry. The analytes Cr, Be, Pb, Cd, Tl, and Hg were converted simultaneously, as hydrophilic anionic iodide species formed with KI in the presence of HCl. The method is based on the formation of extractable ion associates of anionic iodide species with solubilizing cationic and hydrophobic sites of mixed micelles. The mixed micelles are formed by cationic, Aliquat-336 (N-methyl-N,N,N-trioctylammonium chloride) and nonionic, Triton X-114. The ion associates formed are preconcentrated from bulk aqueous phase into a small mixed micelle-rich phase, avoiding the addition of an external chelating agent. The parameters affecting the process are evaluated and optimized. The recoveries of anaytes are in the range of 86–102% at 0.1–10 μg...

Preconcentration and determination of Metformine Hydrochloride in different samples by cloud point extraction coupling with uv-visible spectrophotometry

This work was influenced the separation and preconcentration steps were carried out to determination of metformin (MET) in pharmaceutical preparations and human serum samples. Complex formation method and cloud-point extraction (CPE) coupling with UV-Visible spectrophotometry were used to investigated of study target.The results has showed the best optical characteristic for calibration curve and statistical data which were obtained under optimum conditions. The first method is based on the reaction of MET with nickel (II) in alkaline medium an absorption maximum ?)max) at 434nm. ''Beer's low'' is obeyed in the concentration range (10-100µg.ml-1) with molar absorptivity of 3.9x103 L.mol-1.cm-1.The limit of detection and quantitation values were 2.37 and7.11 µg.ml-1 respectively. The second method based on extraction of traces amounts of MET using the cloud-point extraction (CPE). This method implicated for using of a nonionic surfactant (Triton x-114) as an extraction medium which was entrap the hydrophobic complex formed between MET and nickel(ii) in basic medium as reaction system for designing the CPE procedure. The optimum conditions were similar the first method expect the amount of surfactant which was 0.5 ml. The concentrations range of calibration curve from 3.5to100 µg.ml-1 and molar absorptivity of 1.2x104 L.mol-1.cm-1. In this method was access to less of concentrations in Limit of detection and quantitation which were 0.74and 2.22 µg.ml-1 respectively. The precise (RSD %) and accuracy (recovery %) of both methods were ranged between 0.24-0.47, 97.86-98.68 respectively. The data of two methods were appeared high acceptable with standered of British Pharmacopoeia through using statistic methods (f-test and t-test), that they may be used in analysis of MET.

Application of Cloud Point Extraction for Separation of Iron in Water, Food and Environmental Samples Perior to Determination by Spectrophotometry

A simple, sensitive and selective cloud point extraction procedure (CPE) for separation of trace amount of iron in water, food and environmental samples perior to its determination by spectrophotometry has been developed. The CPE method is based on the reaction of Fe(II) with 7-(1,5-dimethyl-3-oxo-2-phenyl- 2,3-dihydro-1H-pyrazol-4-ylazo)-8-hydroxyquinoline-5-sulphonic acid (DPPAHS) as a new complexing agent yielding a complex at pH 4.5, which extracted in non-ionic surfactant Triton X-114. The total iron was determined after the reduction of Fe(III) to Fe(II) using ascorbic acid. The main parameters affecting the CPE efficiency, such as pH of sample solution, concentration of DPPAHS and Triton X-114, equilibration temperature and time, were investigated and optimized. Under the optimum conditions, the calibration curve was linear in the range of 5.0-140 ng mL-1 with R2 = 0.9994. The detection limit was 1.20 ng mL-1 with preconcentration and enrichment factors of 40 and 183, respectively. The interference of various cations and anions has been studied. The proposed CPE technique has been successfully applied for the determination of trace amount of iron in water, food and environmental samples with high efficiency and satisfactory results.

Preconcentration and determination of vanadium and molybdenum in milk, vegetables and foodstuffs by ultrasonic-thermostatic-assisted cloud point extraction coupled to flame atomic absorption spectrometry

A new ultrasonic-thermostatic-assisted cloud point extraction procedure (UTA-CPE) was developed for preconcentration at the trace levels of vanadium (V) and molybdenum (Mo) in milk, vegetables and foodstuffs prior to determination via flame atomic absorption spectrometry (FAAS). The method is based on the ion-association of stable anionic oxalate complexes of V(V) and Mo(VI) with [9-(diethylamino)benzo[a]phenoxazin-5-ylidene]azanium; sulfate (Nile blue A) at pH 4.5, and then extraction of the formed ion-association complexes into micellar phase of polyoxyethylene(7.5)nonylphenyl ether (PONPE 7.5). The UTA-CPE is greatly simplified and accelerated compared to traditional cloud point extraction (CPE). The analytical parameters optimized are solution pH, the concentrations of complexing reagents (oxalate and Nile blue A), the PONPE 7.5 concentration, electrolyte concentration, sample volume, temperature and ultrasonic power. Under the optimum conditions, the calibration curves for Mo(VI) and V(V) are obtained in the concentration range of 3–340µgL−1 and 5–250µgL−1 with high sensitivity enhancement factors (EFs) of 145 and 115, respectively. The limits of detection (LODs) for Mo(VI) and V(V) are 0.86 and 1.55µgL−1, respectively. The proposed method demonstrated good performances such as relative standard deviations (as RSD %) (≤3.5%) and spiked recoveries (95.7–102.3%). The accuracy of the method was assessed by analysis of two standard reference materials (SRMs) and recoveries of spiked solutions. The method was successfully applied into the determination of trace amounts of Mo(VI) and V(V) in milk, vegetables and foodstuffs with satisfactory results.

Preconcentration and determination of Metformine Hydrochloride in different samples by cloud point extraction coupling with uv-visible spectrophotometry

This work was influenced the separation and preconcentration steps were carried out to determination of metformin (MET) in pharmaceutical preparations and human serum samples. Complex formation method and cloud-point extraction (CPE) coupling with UV-Visible spectrophotometry were used to investigated of study target.The results has showed the best optical characteristic for calibration curve and statistical data which were obtained under optimum conditions. The first method is based on the reaction of MET with nickel (II) in alkaline medium an absorption maximum ?)max) at 434nm. ''Beer's low'' is obeyed in the concentration range (10-100µg.ml-1) with molar absorptivity of 3.9x103 L.mol-1.cm-1.The limit of detection and quantitation values were 2.37 and7.11 µg.ml-1 respectively. The second method based on extraction of traces amounts of MET using the cloud-point extraction (CPE). This method implicated for using of a nonionic surfactant (Triton x-114) as an extraction medium which was entrap the hydrophobic complex formed between MET and nickel(ii) in basic medium as reaction system for designing the CPE procedure. The optimum conditions were similar the first method expect the amount of surfactant which was 0.5 ml. The concentrations range of calibration curve from 3.5to100 µg.ml-1 and molar absorptivity of 1.2x104 L.mol-1.cm-1. In this method was access to less of concentrations in Limit of detection and quantitation which were 0.74and 2.22 µg.ml-1 respectively. The precise (RSD %) and accuracy (recovery %) of both methods were ranged between 0.24-0.47, 97.86-98.68 respectively. The data of two methods were appeared high acceptable with standered of British Pharmacopoeia through using statistic methods (f-test and t-test), that they may be used in analysis of MET.

Development of novel simultaneous single step and multistep cloud point extraction method for silver, cadmium and nickel in water samples

A novel, simple and rapid single and multi-step cloud point extraction procedure was developed for the selective and simultaneous preconcentration of silver, cadmium and nickel in real samples prior to their determination by flame atomic absorption spectrometry. Dithizone was used as neutral hydrophobic complexing agent. Separation of understudy metals can be achieved by controlling the pH value of the extraction system. Evaluation of the two CPE methods was checked by paired t-test, which indicated a non-significant difference. It was successfully applied to the real water sample. Certified reference materials were used for the accuracy of the green extraction methods. The regression equation for the calibration curve was linear in the range of 10–150μgL−1 for Ag, 5–100μgL−1 for Cd, 10–200μgL−1 for Ni. Relative standard deviation (RSD%) values were found to be lower than 2.5% for all elements. Enhancement factor (EF) and limit of detection (LOD) values were found in the range of 41–58 and 0.27–1.12μgL−1, respectively.

Speciation analysis of chromium in water samples through sequential combination of dispersive magnetic solid phase extraction using mesoporous amino-functionalized Fe3O4/SiO2 nanoparticles and cloud point extraction

The present paper describes the sequential combination of dispersive magnetic solid phase extraction (DMSPE) with cloud point extraction (CPE) as a new nonchromatographic approach for preconcentration/redox speciation of chromium with FAAS detection. The method is based on sequential preconcentration of Cr(VI) at pH5.0 onto mesoporous amino-functionalized Fe3O4/SiO2 nanoparticles followed by cloud point extraction of Cr(III) as metallic complex with 4-(2-thiazolylazo)resorcinol (TAR). The variables that play an important role on the performance of both preconcentration methods were thoroughly optimized by means of factorial design. Under optimized condition, an aliquot of 45.0mL of sample was preconcentrated onto 25mg of magnetic nanoparticles during 1min following the elution with 0.5mL of 2.5molL−1 HCl. The supernatant containing Cr(III) was then subjected to CPE procedure, which was accomplished by using thermostatic bath at 90°C during 45min, 5.8×10−4molL−1 TAR and 0.3% (v/v) Triton X-114. The method provided preconcentration factors of 16 and 12 times yielding limits of detection (LOD) and quantification (LOQ) of 1.1 and 3.6μgL−1 for Cr(VI) and 3.2 and 10.5μgL−1 for Cr(III), respectively. A high tolerance toward potentially interfering ions (cations and anions) and humic acid was observed for the method. Precision (n=10) of the procedure determined as relative standard deviation (RSD) were, 5.8 and 3.7% for Cr(III) using solutions at 15.0 and 165.0μgL−1 and 5.5 and 3.0% for Cr(VI) using solutions at 15.0 and 75.0μgL−1 concentrations, respectively. The applicability of method was attested by analysis of water samples yielding good recovery values (91.4–103.5%). The accuracy of method was also checked for biological samples using a certified reference material DORM-3 (Fish Protein Certified Reference Material for Trace Metals).

Triton X-114 cloud point extraction to subfractionate blood plasma proteins for two-dimensional gel electrophoresis

A simple and reproducible procedure for enrichment of a plasma protein subfraction suitable for two-dimensional polyacrylamide gel electrophoresis (2DE) was developed, using a Triton X-114-based cloud point extraction (CPE). Appropriate conditions for such a CPE procedure were found by SDS-PAGE to be a plasma protein concentration of about 10mg/ml in 3% (w/v) Triton X-114. 2DE of proteins obtained by CPE of 400μl of human plasma revealed about 200 spots constituting a spot pattern very different from the pattern of total plasma. The CPE procedure only had a limited contribution to the technical variation. Identification of about 60 spots, representing only 22 proteins, revealed that several proteins in the obtained subfraction were present in more isoforms or modifications. Among these were apolipoproteins (A-1, D, E, L1, and M), haptoglobin-related protein, phosphatidylcholine-sterol acyltransferase, serum amyloid A, and serum paraoxonase/arylesterase 1, which are proteins of a hydrophobic nature, as in plasma they relate to lipoprotein particles. Thus, Triton X-114-based CPE is a simple plasma prefractionation tool, attractive for detailed 2DE studies of hydrophobic plasma proteins and their isoforms or modifications.

A New Micellar Mediated Cloud-Point Extraction Procedure for Sensitive and Selective Determination of Trace Amounts of Total Iodine in Milk-Based Nutritional Products by Means of Indirect Spectrophotometry

A new micellar mediated cloud-point extraction procedure (CPE) has been developed for sensitive and selective determination of trace amounts of total iodine by means of indirect spectrophotometry. The method is based on selective charge transfer complex formation of I3, which is produced by the reaction of iodate in presence of 25-fold excess periodate with excess iodide and with acridine orange (AOH+) being a selective fluorescent cationic dye at pH 3.0 phthalate buffer, and then the CPE of charge transfer complex formed from aqueous solution at phthalate buffer using nonionic surfactant, Triton X-114. The calibration graphs were rectilinear in the ranges of 1.5–20 and 20–160 μg L−1 for IO3 −, with r 2 higher than 0.9996 in two linear regions with changing sensitivity. Under optimal conditions obtained, the limits of detection and quantification were 0.4 and 1.5 μg L−1 and the precision (as RSD) for determination of 10, 50, and 100 μg L−1 of iodate was in the range of 2.4–4.7 % (n 5). The method was successfully applied to selective and reliable determination of total iodine in milk-based nutritional products. The accuracy of the method was controlled by analyzing two standard reference materials (SRMs) at suitable matrix to milk samples.

Cloud Point Extraction Spectrophotometric Method for Mutual Determination of Norfloxacin and Iron(III) in Human Serum and Drug Formulations

An eco-friendly procedure was developed for dual detection of drug norfloxacin (NOR) and iron(III) ions in biological and pharmaceutical samples via the coupling of cloud-point extraction procedure with molecular spectrophotometry. The drug norfloxacin reacts with Fe(III) ions in dilute acidic medium to form a colored hydrophobic (Fe(III)-NOR) complex which initially extracted into micelles of Triton x-114 as a mediated extractant followed the determination of both NOR and Fe(III) ions individually, by using spectrophotometry at same wavelength maximum of 432 nm. To achieve this goal, all experimental variables for both target analytes were previously optimized. The results have shown that the preconcentration factors of 83 and 71 for NOR and Fe(II) leading to achieve a limit of detection of 0.692 μg mL -1 3.42 ng mL -1 with linear range of 2.5- 125 μgmL -1 (r= 0.9998) and 5-150 ng mL -1 (r=0.9997) respectively. The mean recovery percentage of 98.95±1.09% and 98.77±2.29%; the precision (RSD%) ranged between 0.04-0.66% and 0.59- 0.97% were obtained for NOR and Fe(III) respectively. The proposed method was used for the determination of NOR in the serum samples of different subjects orally administration for two hours with Norfloxacin tablets BP 400 mg, in addition to drug formulations like Norflox Eye/Ear drops, While iron was determined in four selected drug formulations and in both cases, the experimental values are agreed with the quoted values that stated by the manufacturer company,

Preconcentration/separation of lead at trace level from water samples by mixed micelle cloud point extraction

A mixed micelle-mediated cloud point extraction procedure was developed for lead. Triton-X114 and benzyldimethyl hexadecyl-ammonium chloride were used as mixed micellar medium. Lead(II) was reacted with 4-(2-pyridylazo) resorcinol at pH 6.0 to form hydrophobic chelates. The parameters including pH, ligand volume, concentrations of surfactants and centrifugation time were optimized. The effect of some common ions was also tested. The limit of detection was 1.15μgL−1 with preconcentration factor of 50. The accuracy of method was evaluated by the analysis of certified reference materials. The method was successfully applied to determination of levels of lead in water samples.

Determination of trace vanadium in sea cucumbers by ultrasound-assisted cloud point extraction and graphite furnace atomic absorption spectrometry

An ultrasound-assisted cloud point extraction (CPE) procedure was used for preconcentration and determination of vanadium by graphite furnace atomic absorption spectrometry. The vanadyl(IV) complex with ascorbic acid form a hydrophobic complex with 4-(2-pyridylazo) resorcinol (PAR) in a micelle medium, which is stable under our working conditions, and followed by its extraction into Triton X-100 surfactant-rich phase. The main factors affecting CPE efficiency, such as pH, concentrations of PAR, ascorbic acid and Triton X-100, incubation temperature, frequency and equilibration time of ultrasonic bath were investigated in detail. Under the optimum conditions, preconcentration of 10 mL sample gave a preconcentration factor of 36.4 and a detection limit of 4.0 µg kg−1. The proposed method was successfully applied to determination of vanadium in sea cucumbers with satisfactory results.

Multivariate Optimization of a Simultaneous Cloud Point Extraction Procedure of Cd, Cu and Ni from Sediments Samples and Determination by ICP OES

A simultaneous preconcentration method for cadmium, copper and nickel in samples of sediments and determination by inductively coupled plasma optical emission spectrometry was developed. The method is based on the extraction of the metals as complexes formed with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (5-Br-PADAP) at cloud point of the nonionic surfactant polyethylene glycol tert-octylphenyl ether (triton X-114). Optimization was performed using a Doehlert design and constrained mixture design. Desirability function was used to provide a simultaneous optimization of the evaluated responses. The developed method presented limits of quantification of 0.066, 0.149 and 0.191 µg g-1 and an enrichment factor of 18.4, 16.8 and 18.2 fold for cadmium, copper and nickel, respectively. The proposed method was applied in sediment samples collected in the urban stretch of the Contas River (Jequie, BA, Brazil). Adequate accuracy was found by analysis of two certified reference materials (NIST 1646a estuarine sediments and NIST 2702 marine sediment).

A cloud point extraction procedure for gallium, indium and thallium determination in liquid crystal display and sediment samples

A simple, sensitive and rapid cloud point extraction (CPE) methodology has been developed for the selective separation and preconcentration of gallium, indium and thallium, after complexation with gallic acid in the presence of Triton X-114 as a non-ionic surfactant.