Abdullah Akdogan

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%.

Liquid–liquid extraction of transition metal cations by nine new azo derivatives calix[n]arene

Liquid–liquid extraction of various alkali, alkaline-earth, and transition metal cations with o-(4-hydroxydiazophenyldiazophenyl)-p-tert-butylphenol (L1), bisdiazo (1-hydroxy-4-tert-butyl-phenyl)benzene (L2), p-(2-hydroxy-5-tert-butylphenylazophenylazo)calix[4]arene (L3), and p-(2-hydroxy-5-tert-butylphenylazophenylazo)calix[6]arene (L4), p-(4-butylphenylazo)calix[6]arene (L5), p-[4-(phenylazo)phenylazo]calix[6]arene (L6), p-(4-hydroxyphenylazo)calix[6]arene (L7), p-{4-[N-(thiazol-2-yl)sulfamoyl]phenylazo}calix[6]arene (L8), p-(4-acetamidophenylazo)calix[6]arene (L9), p-(thiazol-2-ylazo)calix[6]arene (L10), and p-(2-sulfanylphenylazo)calix[6]arene (L11) from the aqueous phase into the organic phase was carried out. For comparison, the corresponding azo calix[n]arene derivatives and two phenol derivatives were also examined. Since Ag +, Hg +, and Hg 2+ cations form complexes with azo groups strongly, the extraction of these metals was found to be highly effective.

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.

Factorial design for multivariate optimization of preconcentration system for spectrophotometric phosphorus determination

The present paper proposes a preconcentration procedure for phosphorus determination by using ultraviolet-visible spectrophotometer. It is based on the formation of phosphomolybdate and its reduction to molybdenum blue. Phosphorus extraction as phosphomolybdenum blue complex was performed onto Amberlite XAD-4. The optimization step was carried out using two-level full factorial design. Three variables (resin amount, sample volume, flow rate) were regarded as factors in the optimization. The relative standard deviation was 2% at 0.08 microg mL(-1). The limit of detection was found to be 2.23 microg L(-1) (N=15). The proposed solid-phase extraction procedure was applied to phosphorus in some fruit leaves, natural waters, and a standard reference material (SRM 1515 apple leaves).

Determination of Triazine Herbicides and Metabolites by Solid Phase Extraction with HPLC Analysis

An efficient solid phase extractive preconcentration/separation method was developed for the trace determination of herbicides in aqueous samples using Amberlite XAD-4 resin as the adsorbent. The retained herbicides were eluted with methanol at a flow rate of 1.0 mL min−1 and determined by HPLC-DAD (wavelength of 220 nm) using water (pH:4.7, phosphoric acid) and methanol (ratio 35:65) as the mobile phase with a flow rate of 1.0 mL min−1. Quantitative recoveries of simazine, atrazine and its metabolities were achieved at optimized analysis conditions that included 0.75 g of resin; a pH of 3.0; an eluent volume of 3.0 mL; an eluent flow rate of 1.0 mL min−1; and a sample flow rate of 4.0 mL min−1. The limits of detection, preconcentration factor, and linear ranges for the herbicides were 0.084–0.121 µgL−1, 1000, and 0.5–20 mg L−1, respectively. The performance of the method was evaluated by analysis of spiked water samples. The recoveries of simazine, atrazine and their metabolities were found to be quantitative (99.6–104.8%) with RSDs of 2.2–4.8% and 2.8–4.7% for intra-day and inter-day precision, respectively. The proposed method was successfully applied for trace determination of studied analytes in waste water, apple juice, and red wine samples.

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.

Single-laboratory validation of a saponification method for the determination of four polycyclic aromatic hydrocarbons in edible oils by HPLC-fluorescence detection

ABSTRACT An analytical method is reported for the determination of four polycyclic aromatic hydrocarbons (benzo[a]pyrene (BaP), benz[a]anthracene (BaA), benzo[b]fluoranthene (BbF) and chrysene (CHR)) in edible oils (sesame, maize, sunflower and olive oil) by high-performance liquid chromatography. Sample preparation is based on three steps including saponification, liquid–liquid partitioning and, finally, clean-up by solid phase extraction on 2 g of silica. Guidance on single-laboratory validation of the proposed analysis method was taken from the second edition of the Eurachem guide on method validation. The lower level of the working range of the method was determined by the limits of quantification of the individual analytes, and the upper level was equal to 5.0 µg kg−1. The limits of detection and quantification of the four PAHs ranged from 0.06 to 0.12 µg kg−1 and from 0.13 to 0.24 µg kg−1. Recoveries of more than 84.8% were achieved for all four PAHs at two concentration levels (2.5 and 5.0 µg kg−1), and expanded relative measurement uncertainties were below 20%. The performance of the validated method was in all aspects compliant with provisions set in European Union legislation for the performance of analytical methods employed in the official control of food. The applicability of the method to routine samples was evaluated based on a limited number of commercial edible oil samples. Graphical Abstract