Aysen Hol

Selective extraction of chromium(VI) using a leaching procedure with sodium carbonate from some plant leaves, soil and sediment samples

Speciation of chromium in some plant leaves, soil and sediment samples was carried out by selective leaching of Cr(VI) using a sodium carbonate leaching procedure. Total chromium from the samples was extracted using aqua regia and oxidative acid digestion, respectively. The concentrations of chromium species in the extracts were determined using by graphite furnace atomic absorption spectrometry (GFAAS). Uncoated graphite furnace tubes were used as an atomizer. Due to the presence of relatively high amounts of Na(2)CO(3) in the resulting samples, the possible influences of Na(2)CO(3) on the absorbance signals were checked. There is no interference of Na(2)CO(3) on the chromium absorbance up to 0.1 mol L(-1) Na(2)CO(3). A limit of detection (LOD) for determination of Cr(VI) in 0.1 Na(2)CO(3) solution by GFAAS was found to be 0.93 microg L(-1). The procedure was applied to environmental samples. The relative standard deviation, R.S.D. as precision for 10 replicate measurements of 20 microL(-1) Cr in processed soil sample was 4.2%.

A novel strategy for chromium speciation at ultra-trace level by microsample injection flame atomic absorption spectrophotometry

Simple, robust and novel analytical procedures were developed for the speciation of chromium by carrier element co-precipitation (CECP) and dispersive liquid–liquid microextraction (DLLME) coupled with microsample injection system–flame atomic absorption spectrophotometry (MIS–FAAS). Ammonium pyrrolidine dithiocarbamate (APDC), carbon tetrachloride and ethanol were used as chelating agent, extraction solvent and disperser solvent, respectively for the determination of Cr(VI) by DLLME. For total chromium, Cr(III) was oxidized by Ce(SO4)2 in acidic media (0.07 mol L−1 H2SO4) and the resulting solution was co-precipitated with APDC. The concentration of Cr(III) was estimated by determining the difference between the concentration of total chromium and that of Cr(VI). The maximum recovery of Cr(VI) was obtained with DLLME at optimal conditions of pH 3.0 , 0.25% APDC, 100 μL CCl4, 1.00 mL of CH3CH2OH and 0.01 mg L−1 Cr(VI). Whereas, the optimal conditions for CECP were 40 mL initial volume of water samples, 0.25% APDC, 0.02% Ce(SO4)2 and 0.10 mg L−1 Cr(VI) concentration. The limits of detection and enrichment factor of DLLME and CECP were [0.037 and 2.13] and [400 and 100] μg L−1, respectively with 40 mL initial volumes. The relative standard deviations (RSD, n = 6) were <4%. The proposed method was successfully applied to the chromium speciation at ultra-trace levels in natural drinking water, industrial effluents waste water and an exchangeable fraction of garden soil from Denizli. Moreover, the proposed methods compared well with the literature reported method.

Transport of Pb(II) by supported liquid membrane containing p-tert-butyl calix[4]amine derivative as carrier

AbstractFacilitated transport of Pb(II) ions in acidic medium, across a supported liquid membrane (SLM) by using 5,11,17,23-tetra-tert-butyl, 25,27-bis(benzylamino etoxy)-26,28-dihydroxycalix[4]arene as carrier, dissolved in kerosene, has been investigated. The parameters studied are Pb(II) ions concentration in the feed phase, HCl concentration in the stripping phase, and solvent effect in the membrane phase. The Celgard 2500 membrane was used as the solid support. A Danesi mass transfer model was used to calculate the permeability coefficients for each parameter studied. Also, AFM technique and contact angle measurements were used to characterize the surface morphology of the prepared Celgard 2500-carrier 1 SLM.

Facilitated Transport of Zn(II) and Cd(II) Ions Through Polymer Inclusion Membranes Immobilized With a Calix[4]resorcinarene Derivative

The transport of Zn(II) and Cd(II) ions from aqueous nitrate donor phase solution (1×10−3M) by polymer inclusion membranes (PIMs) has been investigated using 2,8,14,20-tetrahekxyl-4,6,10,12,16,18,22,24-oktahydroxycalix[4]resorcinarenes as the carrier. The Zn(II) and Cd(II) ions were transported through PIM of cellulose triacetate (CTA) as a polymeric support material and 2-NPOE as a plasticizer. The prepared PIM was characterized by Fourier Transform Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy(SEM), and Atomic Force Microscopy (AFM) techniques. The efficiency of the transport of Zn(II) and Cd(II) ions through the PIM was investigated in terms of the effects of carrier concentration, the pH in the acceptor phase, the amount of plasticizer in the membrane and the thickness of the membranes. The kinetic parameters which have been calculated as the constant rate (k), permeability coefficient (P), flux (J) and diffusion coefficient (D). This study has demonstrated the driving force of pH through the mechanism of carrier mediated diffusion of transport of Zn(II) and Cd(II) ions. These results indicates that PIMs can be used effectively for the removal of Zn(II) and Cd(II) ions from industrial waste waters.

Determination of Chlorophenols and Alkylphenols in Water and Juice by Solid Phase Derivative Extraction and Gas Chromatography–Mass Spectrometry

A solid phase derivative extraction method using acetic anhydride was developed for the determination of chlorophenols and alkylphenols in water and fruit juice by gas chromatography–mass spectrometry (GC–MS). The quantitative extraction was performed by passing 100 mL of sample prepared in 0.1 mol L−1 sodium hydroxide through a column packed with 500 mg of a strong anion-exchange resin at a flow rate of 0.75 mL min−1. The retained phenols were quantitatively derivatized in the column by the introduction of 0.25 mL of acetic anhydride. The derivatized phenols were eluted with 3.0 mL of hexane and the effluent was dried under nitrogen. The final volume was diluted to fifty microliters with hexane and analyzed by GC–MS. Under the optimum conditions, preconcentration factors of 2000, limits of detection between 0.005 and 1.796 µg L−1, and relative standard deviations of 2.1% to 6.7% were obtained. The method was successfully applied to wastewater and fruit juice and the recoveries of phenols were between 76% and 111%.

Simultaneous Solid Phase Chelate Extraction for Ultratrace Determination of Copper, Nickel, and Zinc by Microsample Injection System Coupled Flame Atomic Absorption Spectrometry

A simple and accurate solid phase extraction method was developed for the determination of Cu(II), Ni(II), and Zn(II) at trace levels by microsample injection system coupled flame atomic absorption spectrometry. The proposed method is based on the retention of complexes of metal ions with 4-(2-pyridylazo) resorcinol on Amberlite XAD-7 resin and elution with acetone. The possible parameters influencing the preconcentration were optimized. The interferences of coexisting ions were studied. Under the optimal conditions, the detection limits of Cu(II), Ni(II), and Zn(II) were 0.058, 0.013, and 0.027 µg L−1, respectively. The applicability and the accuracy of the proposed method were validated by analysis of BCR 715 wastewater as a certified reference material and spiked real samples. Recoveries in the range of 94–105% were obtained with relative errors less than 7.5% and relative standard deviations less than 3.2%.

Dispersive Liquid–Liquid Microextraction of Nickel Prior to Its Determination by Microsample Injection System-Flame Atomic Absorption Spectrometry

A sensitive and simple method for the determination of trace nickel was developed by the combination of dispersive liquid–liquid microextraction (DLLME) and microsample injection system–flame atomic absorption spectrometry (MIS–FAAS). Trace nickel was preconcentrated as the 8-hydroxyquinoline chelate by DLLME, and the conditions were optimized by a Plackett-Burman design. Quantitative recovery of nickel (98 ± 1%) was obtained by a sample volume of 7.5 mL at a pH of 6.0. The enrichment factor was 52.5, and the limits of detection and quantitation were 0.1 µ g L−1 and 3.0 µ g L−1, respectively. The method was validated by the analysis of a wastewater standard reference material, water samples, and a wire sample. The reported method has superior analytical figures of merit compared with similar methods reported in the literature.

Synthesis and characterisation of novel chelating resin for selective preconcentration and trace determination of Pb(II) ions in aqueous samples by innovative microsample injection system coupled flame atomic absorption spectrometry

Expanded polystyrene (EPS) foam waste (white pollutant) was utilised for the synthesis of novel chelating resin i.e. EPS-N = N-α-Benzoin oxime (EPS-N = N-Box). The synthesised resin was characterised by FT-IR spectroscopy, elemental analysis, and thermogravimetric analysis. A selective method for the preconcentration of Pb(II) ions on EPS-N = N-Box resin packed in mini-column was developed. The sorbed Pb(II) ions were eluted with 5.0 mL of 2.0 mol L−1 HCl and determined by microsample injection system coupled flame atomic absorption spectrometry (MIS-FAAS). The average recovery of Pb(II) ions was achieved 95.5% at optimum parameters such as pH 7, resin amount 400 mg, flow rates 1.0 mL min−1 (of eluent) and3.0 mL min−1 (of sample solution). The total saturation capacity of the resin, limit of detection (LOD) and limit of quantification (LOQ) of Pb(II) ions were found to be 30 mg g−1, 0.033 μg L−1 and 0.107 μg L−1, respectively with preconcentration factor of 300. The accuracy, selectivity and validation of the method was checked by analysis of sea water (BCR-403), wastewater (BCR-715) and Tibet soil (NCS DC-78302) as certified reference materials (CRMs). The proposed method was applied successfully for the trace determination of Pb(II) ions in aqueous samples.

Determination of Pesticides in Soil by Mechanical Stirring-Assisted Extraction Coupled with Gas Chromatography-Mass Spectrometry

This work describes the development of an analytical method for determining the mobility of some organophosphorus and azole group pesticides. The chromatographic and mass spectrophotometric parameters were optimized. The target pesticides were recovered quantitatively (79.3–95.6%) with a relative standard deviation less than 8.5% at the optimum conditions of the extraction. The limits of detection of the target pesticides were found to be in the range of 0.16 to 1 . 14 µ g kg − 1 with a correlation coefficient ( r) > 0 . 9955 . The method was validated in the target environmental matrices by the analysis of a spiked soil sample. The proposed method was successfully applied for the determination of pesticides in vineyard soil samples and statistically evaluated.

Schiff base-functionalised styrofoam resin for preconcentration of metal ions in wastewater and wastewater-irrigated vegetables samples

Polystyrene (PS) was extracted from styrofoam waste and functionalised with schiff base, N,N-bis(salicylidene)cyclohexanediamine (SCHD) through an azo spacer. The resin was characterised and used for preconcentration of Pb(II), Ni(II) and Cd(II) ions prior to their trace determinations by microsample injection system–coupled flame atomic absorption spectrometry (MIS-FAAS). The recoveries of studied metal ions were achieved ≥96.0% with relative standard deviation (RSD) ≤4.5 at optimum parameters: pH 8; resin amount 300 mg; flow rates 3.0 mL min−1 of sample solution; and 2.0 mL min−1 of eluent (2.0 mol L−1 HNO3). The limits of detection (LODs) and limits of quantification (LOQs) were found to be 0.32, 0.23 and 0.21 and 1.10, 0.78 and 0.69 μg L−1, respectively, with preconcentration factors (PFs) of 500, 800 and 1000, respectively. The linear ranges of the method were 1–40, 1–25 and 1–20 μg L−1 for Pb(II), Ni(II) and Cd(II) ions, respectively. The accuracy and validation of the method were evaluated by analysis of certified reference materials (CRMs). The method was successfully applied for preconcentration of studied metal ions in wastewater and wastewater-irrigated vegetable samples.