A simple ligandless microextraction method based on ionic liquid for the determination of trace cadmium in water and biological samples

A simple and efficient ionic liquid-based ligandless microextraction method has been developed for preconcentration of cadmium ions (Cd²⁺) as a step prior to its determination by flame atomic absorption spectrometry (FAAS) with a micro-sample introduction system. In this approach, the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate [C₄mim][PF₆] and ethanol were used as extractant and dispersive solvents to preconcentrate the Cd²⁺ in different waters, acid digested scalp hair, and nail samples. Some analytical parameters influencing the extraction efficiency of Cd²⁺ and its subsequent determination, including pH, IL volume, dispersant solvent volume, sample volume, temperature, incubation time, and matrix effect, were optimized. Under optimal conditions, the limit of detection (LOD), limit of quantification (LOQ), and enhancement factor (EF) were 0.4 μg L^?1, 1.3 μg L^?1, and 50, respectively. The relative standard deviation (RSD) of 100 μgL^?1 Cd²⁺ was 4.3% (n = 6). The validity of the proposed method was checked by determining Cd²⁺ in certified reference material (TM-25.3 fortified water) and standard addition; the results showed sufficient recovery (>98%) of Cd²⁺ within the certified value. The method was applied for preconcentration and determination of cadmium in waters and biological samples.     

Ligand-less in situ surfactant-based solid phase extraction for preconcentration of silver from natural water samples prior to its determination by atomic absorption spectroscopy

A simple and rapid ligand-less in situ surfactant-based solid phase extraction method for preconcentration of silver from water samples is developed. In this method, a cationic surfactant containing a proper alkyl group (n-dodecyltrimethylammonium bromide) is dissolved in the aqueous sample and then a proper ion-pairing agent (ClO₄^?) is added. Due to the interaction between surfactant and ion-pairing agent, solid particles are formed and used for adsorption of silver carbonate. After centrifugation, the sediment is dissolved in 2.0 mL 1 M HNO₃ in ethanol and then aspirated directly into the flame atomic absorption spectrometer. Variables affecting the extraction efficiencies such as pH, concentrations of surfactant and CO₃^2?, ion pair concentration, and extraction time, are optimized. Under such conditions, the calibration curve is linear from 3 to 700 μg L^?1. Detection limit is 1.1 μg L^?1 with an enrichment factor of 37. The relative standard deviation for eight replicate measurements of 100 μg L^?1 is 2.1%. The method has been applied for the determination of silver in water samples.     

A novel ligand for cloud point extraction to determine gold content in ore samples

Gold is a valuable metal occurring usually at very low concentrations in complex natural samples. Gold analysis thus needs preconcentration methods. Classical liquid–liquid extraction involves hazardous organic solvents. Alternatively, cloud point extraction involves non-toxic and nonvolatile surfactants. Here, we analyzed ore samples. The complex of Au(III) with sulphapyridylazo resorcin was extracted by the cloud point method. Concentrations were measured by flame atomic absorption spectrometry. We tested the effects of pH, reagent concentration, Triton X-100 surfactant concentration, equilibration temperature and time. Results show that the best detection limit of the method was 0.48 µg L^?1 for Au with a preconcentration factor of 31 times. Calibration is linear in range of 6.4–2,000 µg L^?1, and relative standard deviations are lower than 5 %. Quantum chemical computations reveal the plausible structure of the gold–ligand complex. This report represents the first determination of gold using sulphapyridylazo resorcin as a ligand.     

Determination of cobalt by air-assisted liquid–liquid microextraction

Abstract

A rapid and selective technique for extraction, preconcentration and determination of trace amounts of cobalt in water and pharmaceutical samples by air-assisted liquid–liquid microextraction combined with flame atomic absorption spectrometry is proposed. 1-Nitroso-2-naphthol is used as a complexing agent and 1-octanol as an extraction solvent. Parameters relevant for analytical effectivity, i.e. pH of sample solution, concentration of complexing agent, volume of extraction solvent, and number of extraction cycles are optimized using a Box–Behnken design. At optimum conditions, a dynamic linear range of 5–600?µg L^?1 is obtained, with a limit of detection of 1.2?µg L^?1. The method is used for determination of Co(II) in environmental water and pharmaceutical samples.     

Quantification of TiO2 and ZnO nanoparticles in wastewater using inductively coupled plasma optical emission spectrometry

Abstract

The applicability of inductively coupled plasma optical emission spectrometry has been examined for determination titanium dioxide and zinc oxide nanoparticles in industrial wastewater samples. The extraction and preconcentration of the nanoparticles were achieved using ligandless ultrasound-assisted surfactant-based dispersive liquid–liquid microextraction. Under optimized conditions, the developed method had limits of detection (LOD) of 2.7?ng L^?1 for Ti and 3.6?ng L^?1 for Zn resulting from dissolved TiO₂ and ZnO nanoparticles. The relative standard deviation values for intraday precision were 2.5% and 3.1% for TiO₂ and ZnO, while the interday precision was 4.5% and 5.0%. Percentage recoveries ranging from 98% to 100% were obtained. Finally, the applicability of the method was examined by analyzing spiked samples and wastewater samples collected from textile, cosmetic and paint industries.     

Bestimmung von leicht freisetzbarem Cyanid in Böden und Wässern mit der Mikrodestillation

Easy-liberatable cyanide has to be analysed if soils and waters are contaminated by cyanide. The aim of this study was to determine easy-liberatable cyanide in these environmental samples using a micro-distillation apparatus by means of a modified digestion vessel. Pure aqueous solutions of different cyanide species, five contaminated and uncontaminated soil samples and two water samples were analysed by micro-distillation according to the German standards. Recovery was determined by analysis of spiked samples. When using the modified digestion vessels, the pH of 4 which is demanded by the standard method can be adjusted. The recovery of potassium cyanide and weakly-complexed zinc-cyanide ranged from 93–101% for standards, and from 87–98% for spiked samples. In contrast, the recovery of strong iron-cyanide complexes was below 4% both for pure solutions and spiked samples. The precision of the method expressed as a relative standard deviation was 25% in cases of very low easy-liberatable cyanide contents (< 1 mg CN kg^?1) and below 12% in case of high easy-liberatable cyanide contents (> 1 mg CN kg^?1) for contaminated soils. The determination of easily-liberatable cyanide in soils and waters using micro-distillation combined with the modified digestion sample is an alternative to other distillation methods.     

A sensitive method for selective determination of vanadium species by dispersive liquid–liquid microextraction (DLLME) with spectrophotometric detection

A simple, fast, and low-cost analytical procedure was developed for trace-level determination of inorganic vanadium species by dispersive liquid–liquid microextraction in combination with spectrophotometry. Vanadium in pentavalent form, V(V), was quantitatively extracted into organic phase as 4-(2-pyridylazo)-recorcinol (PAR) complex in the presence of N-cetyl-N,N,N-trimethyl ammonium bromide (CTAB) as counter-ion. Vanadium (IV) was masked with 1,2-diaminocyclohexanetetraacetic acid to allow speciation analysis. Total vanadium was determined after oxidation of V(IV) to V(V). The main factors affecting preconcentration and spectrophotometric detection of vanadium species such as pH, concentration of PAR and CTAB, the type and volume of the extraction, and disperser solvents were optimized. The limit of detection and enhancement factor obtained under optimum conditions were found to be 0.06 μg L^?1 and 98, respectively. Relative standard deviations for V(IV) and V(V) at 3.0 μg L^?1 were less than 2.4%. The presented procedure was applied to environmental water samples for selective determination of vanadium species. Moreover, the method was applied to determination of vanadium in edible salt samples, due to its applicability in high-NaCl-containing solutions. The validity of proposed method was proven by spike recovery experiments and also independent analysis by inductively coupled plasma mass spectrometry.     

Biosolids application affects the competitive sorption and lability of cadmium,copper, nickel,lead, and zinc in fluvial and calcareous soils

The objective of this research was to investigate the effects of biosolids on the competitive sorption and lability of the sorbed Cd, Cu, Ni, Pb, and Zn in fluvial and calcareous soils. Competitive sorption isotherms were developed, and the lability of these metals was estimated by DTPA extraction following their sorption. Sorption of all metals was higher in the fluvial than in the calcareous soil. Sorption of Cu and Pb was stronger than that of Cd, Ni, and Zn in all soils. Biosolids application (2.5%) reduced the sorption of all metals especially Cu and Pb (28–43%) in both soils (especially the calcareous soil) at the lower added metal concentrations (50 and 100 mg L^?1). However, it increased the sorption of all metals especially Pb and Cu in both soils (especially the calcareous soil; 15.5-fold for Cu) at the higher added concentrations (250 and 300 mg L^?1). Nickel showed the highest lability followed by Cd, Zn, and Pb in both soils. Biosolids increased the lability of the sorbed Ni in the fluvial soils at all added concentrations and the lability of Cd, Pb, and Zn at 50 mg L^?1, but decreased the lability of Cd, Pb, and Zn at 250 and 300 mg L^?1 in both soils. We conclude that at low loading rate (e.g., 50 mg L^?1) biosolids treatment might increase the lability and environmental risk of Cd, Cu, Pb, and Zn. However, at high loading rate (e.g., 300 mg L^?1) biosolids may be used as an immobilizing agent for Cd, Cu, Pb, Zn and mobilizing agent for Ni.     

Preconcentration of samarium with modified yeast cells for its determination by atomic emission spectroscopy

A chelating-modified biosorbent is produced by coupling of a dye, procion red, to yeast cells. The resulting modified cells have been characterized by Fourier transform infrared, elemental analysis and thermogravimetric analysis and studied for preconcentration and determination of trace Sm(III). The optimum pH value for sorption of the samarium ions is 6.2. The sorption capacity of functionalized modified yeast cells is 7.2 mg g^?1. Recovery was 99% when Sm(III) was eluted with an aqueous solution of 0.1 mol L^?1 ethylenediaminetetraacetic acid. Scatchard analysis suggested that binding sites were homogeneous. The equilibrium data were analyzed using Langmuir, Freundlich, Temkin, and Redlich–Peterson isotherm models, and the respective constants were determined as 1.0 (L mg^?1), 2.9 [(mg g^?1) (L mg^?1)^1/n], 2.4 × 10⁸ (L g^?1), and 30 (dm³ g^?1) at 20 °C. The method was applied for an Sm(III)-containing sample of ceramic industry effluent.     

A fast and reliable method for quantitative determination of total mercury in vegetables

A cloud-point extraction (CPE) process using the nonionic surfactant, polyethylene glycol tert octylphenyl ether (Triton X-114) was employed for determination of Hg(II) ions in aqueous solutions. The method is based on the ion-pairing reaction of Hg(II) with Pyronin B (PyrB⁺) in the presence of excess iodide at pH 6.0 and extraction of the complex formed. The chemical variables affecting CPE efficiency were studied, and the analytical characteristics of the method were obtained. The calibration curves were linear in the range of 1–40 μg L^?1 with the detection limits of 0.35 and 0.30 μg L^?1 at 556 and 521 nm. Selectivity was also tested. The coefficients of variation of the method are 2.4% and 5.2% for five replicate measurements of mercury at levels of 10 and 25 μg L^?1, respectively. The results obtained for two certified reference samples were in a good agreement with the certified values. The method was applied to the determination of total mercury in vegetable samples.     

Ultrasound-assisted emulsification/microextraction based on solidification of trace amounts of thallium prior to graphite furnace atomic absorption spectrometry determination

In the present work, determination of ultratrace amounts of thallium in water samples was performed by ultrasound-assisted emulsification microextraction based on solidification of a floating organic drop as sample preparation method prior to furnace atomic absorption spectrometry. 1-(2-Pyridylazo)-2-naphthol was used as chelating agent. The factors influencing the complex formation and extraction, such as pH of the aqueous solution, the type and the volume of extraction solvent, the volume of chelating agent solution, and the extraction time were investigated. Under optimized conditions, the enrichment factor was 200. The calibration graph was linear from 0.2 to 10.0 μg L^?1 with a correlation coefficient of 0.9966, the detection limit was 0.03 μg L^?1 and reproducibility was ±3.3% (C = 5.0 μg L^?1, n = 8). The method was successfully applied for the determination of thallium in water samples.     

Spectrophotometric and HPLC method for quantification of Loratadine on swabs for cleaning validation

Cleaning validation is a major challenge in multi-product pharmaceutical industries. UV spectrophotometric and HPLC methods have been developed and validated for determination of residual amount of Loratadine. Both methods were validated for linearity, range, accuracy, precision, and robustness. The limit of quantification was 1 mg L^?1 by UV spectrophotometric method and 0.5 mg L^?1 by HPLC method. A spike recovery study was done on a stainless steel (316 grade) plate and specific residual cleaning level (SRCL) was down to 6 μg 25.8 cm^?2. Recovery was found to be more than 70%. Both methods were simple, highly sensitive, precise, and accurate, and have potential of being useful for routine quality control.     

Synthesis of 2,3-dihydroxynaphthalene-functionalized Amberlite XAD-4 resin: Applications for the separation and preconcentration of trace metal ions prior to their determination by inductively coupled plasma atomic emission spectrometry

A simple, sensitive column solid-phase extraction procedure for separation and preconcentration of Cu(II), Ni(II), Co(II), and Cd(II) in spiked and natural water samples using 2,3-dihydroxynaphthalene-functionalized Amberlite XAD-4 (XAD-4-DHN) chelating resin prior to their determination by inductively coupled plasma atomic emission spectrometry was discussed. The optimum experimental parameters such as pH, volume of sample and eluent, flow-rates of uptake and stripping, and sorption capacity of the chelating resin, were evaluated. The effect of the electrolytes and the cations on the preconcentration of metal ions was also investigated. The chelating resin could be reused for more than 20 cycles of sorption–desorption without any significant change (<1.0%). Recoveries obtained from this method range from 96 to 102% with R.S.D of 2.50 (n = 4). The detection limits for Cu(II), Ni(II), Co(II), and Cd(II) were found to be 1.9, 0.9, 1.2 µg, and 1.4 µg L^?1, respectively. The proposed method was applied for the determination of Cu(II), Ni(II), Co(II), and Cd(II) in spiked, tap water, and river water samples.     

Determination of Au(III) and Pd(II) ions by flame atomic absorption spectrometry in some environmental samples after solid phase extraction

A simple and sensitive solid phase extraction method was developed for simultaneous separation and preconcentration of gold and palladium ions with N-(4-methylphenyl)-2-{[(4-phenyl-5-pyridine-4-yl-4H-1,2,4-triazol-3-yl)thio]acetyl}hydrazine carbo thioamide complex on Amberlite XAD-1180 resin before their determination by flame atomic absorption spectrometry. Some analytical parameters such as HNO₃ concentration of the sample solution, amount of complexing agent, sample volume, eluent type and volume, effects of foreign ions and adsorption capacity of the resin were investigated for quantitative recovery of gold and palladium ions. The effects of some anions and cations were also examined. Under optimum conditions, the detection limits for gold and palladium ions were found to be 0.29 and 0.19 μg L^?1, respectively. The preconcentration factor for gold and palladium was 250. After being validated by standard addition and analysis of standard reference material, the procedure was successfully applied to the analysis of sea and stream water, anodic slime, gold ore, soil and electronic waste.     

Determination of cadmium in water and herbal medicine by Penicillium chrysogenum immobilized on silica gel for flame atomic absorption spectroscopy

Penicillium chrysogenum was immobilized on silica to develop a simple and cost effective method for solid phase extraction of Cd(II) and determination using flame atomic absorption spectrometry (FAAS). The sorbent was characterized by Fourier transform infrared spectroscopy and packed into a column. The conditions for quantitative sorption and desorption of Cd(II) were optimized. The preconcentration factor was 100 while detection limit was 0.61 µg L^?1 with a relative standard deviation of 1.0%. The method was applied for determination of Cd in herbal medicine and tap water.     

Evaluation of the toxicity of tetrabromobisphenol A and some of its oxidation products using a micro-scale algal growth inhibition test

A micro-scale algal growth inhibition (μ-AGI) test using a common micro-plate based fluorometric detection was used to demonstrate the effects of humic substances (HSs) on the toxicity of tetrabromobisphenol A (TBBPA) and its oxidative decomposition products 2,5-dibromo-1,4-benzoquinone (2,5-DBBQ), 2,5-dibromohydroquinone (2,5-DBHQ), 2,6-dibromobenzoquinone (2,6-DBBQ), and 2,6-dibromophenol (2,6-DBP) to Pseudokirchneriella subcapitata. The EC₅₀ values were: EC_50(TBBPA) = 7 mg L^?1, EC_50(2,5-DBHQ) = 7 mg L^?1, EC_50(2,5-DBBQ) = 19 mg L^?1, EC_50(2,6-DBP) = 49 mg L^?1, and EC_50(2,6-DBBQ) = 13 mg L^?1. The toxicity of the chemicals was slightly lower in the presence of HA. The toxicity of TBBPA decomposed by a biomimetic catalytic system consisting of iron (III) 5,10,15,20-tetrakis (p-sulfonatophenyl) porphyrin (Fe(III)-TPPS) and KHSO₅ was also evaluated using P. subcapitata and Chlamydomonas reinhardtii.     

Rapid and sensitive headspace gas chromatographic method for cyanide determination in whole blood

We reported a simple and rapid headspace (HS) gas chromatographic (GC) assay for the determination of cyanide in human whole blood obtained from both cadaveric and intoxicated subjects. The poison was extracted from whole blood samples by HS technique after 10 min incubation at 80°C with a HCl (1N) acidic solution supplemented with 30 g L^?1 of sodium chloride and 10 mg L^?1 of isopropanol as internal standard. A SGE WAX capillary column (30 m × 0.32 mm ID × 0.5 µm df) was used. The Flame Ionization Detector (FID) was set at 250°C. The detection and the quantification limits were 0.02 and 0.2 mg L^?1, respectively. In the within-day study, the coefficients of variation for three different whole blood cyanide concentrations varied between 3.2 and 6.5%, whereas those in the day-to-day study varied between 4.8 and 6.3%. The assay was performed in less than 20 min per sample, which appears to be suitable for emergency toxicological tasks involved in diagnosis of cyanide poisoning.     

Online solid phase preconcentration using EGDMA–MAA copolymer for lead determination by FAAS

A Ethylene glycol dimethacrylate (EGDMA) methacrylic acid (MAA) resin was used for preconcentration of lead at trace levels in water samples. For this purpose, a flow-injection, solid phase extraction method was developed for the determination of lead by flame atomic absorption spectrometry. Lead ions were sorbed on a EGDMA–MAA column at pH 4, followed by an elution step using 288 µL of 4.0 M nitric acid solution and determination by flame atomic absorption spectrometry. Optimum conditions for quantitative sorption involving the pH, sample volume, loading and elution flow rates, eluent type, and volume were investigated. A 868-fold enrichment factor could be reached. The detection limit for the water samples, estimated from the noise on the signal obtained for 250 mL of 10 µg L^?1 loaded at 4.9 mL min^?1 was 1.04 µg L^?1. The method was applied for lead determination in river water samples collected in Edirne, Turkey. Recoveries of spiked solutions (10 µg L^?1) to river water samples were quantitative. Finally, the method was validated by the analysis of certified reference material SRM 2704 (Buffalo River Sediment).     

Solid phase extraction of trace metals from environmental samples using Amberlite XAD-7 loaded with 2-hydroxy-propiophenone-4-phenyl-3-thiosemicarbazone and determination by inductively coupled plasma–atomic emission spectrometry

A method for the solid phase extraction of trace metals, namely Co, Cu, Pb, Ni and Zn, from environmental and biological samples using column Amberlite XAD-7 loaded with 2-hydroxy-propiophenone-4-phenyl-3-thiosemicarbazone (HPPPTSC) and determination by inductively coupled spectrometry (ICP–AES) has been developed. The reagent has the capacity to form chelate complexes with the metals because of three binding sites in the reagent molecule. The optimum experimental conditions for the quantitative sorption of five metals, pH, effect of flow rate, concentration of eluent, sorption capacity and the effect of diverse ions on the preconcentration of analytes have been investigated. The sorption capacity of the resin has 83, 127, 35, 88 and 85?µmol?g^?1 for Co²⁺, Cu²⁺, Pb²⁺, Ni²⁺ and Zn²⁺, respectively. The preconcentration factors for Co²⁺, Cu²⁺, Pb²⁺, Ni²⁺ and Zn²⁺ were 100, 110, 120, 140 and 150, respectively. The accuracy of the proposed procedure was evaluated by standard reference materials. The achieved results were in good agreement with certified values. The proposed method was applied for the determination of trace metals in river water and plant leaves.     

Spectrophotometry determination of Congo red in river water samples using nanosilver

A spectrophotometric procedure for the anionic diazo dye Congo red was proposed based on nanosilver catalyzed oxidation by potassium iodate in a hydrochloric acid medium. The calibration graph is linear for 0.8–240?mg?L^?1, and the detection limit is 0.6?mg?L^?1. Most foreign ions do not interfere with the determination, except for Cu(II), Fe(III), and Cr(VI). The interferences of Cu(II) and Fe(III) could be eliminated by masking with ethylene diamine tetraacetate, and that of Cr(VI) by reducing to Cr(III) with ascorbic acid. The typical features of this procedure are that it is sensitive for Congo red, and the determination could be carried out at room temperature. It had been used for the determination of Congo red in the Ganjnameh river water sample.