Multi-element determination in some foods and beverages using silica gel modified with 1-phenylthiosemicarbazide.

1-Phenylthiosemicarbazide bonded modified silica gel (PTC-SG) was synthesised and characterised by FTIR, SEM and elemental analysis for a novel separation/preconcentration of multiple elements based on solid phase extraction. The analytical parameters including pH of solutions, amounts of PTC-SG, flow rates of sample, eluent type and sample volume were optimised. The adsorption capacities of PTC-SG were found to be 7.9, 6.4, 6.3, 8.3, 7.2, 8.9 and 6.6 mg/g for Cu(II), Cd(II), Pb(II), Co(II), Cr(III), Ni(II) and Mn(II), respectively. The limit of detection (LOD) was calculated as 3x the standard deviation(s) of the reagent blank (k = 3, N = 21) and the LOD values were obtained to be 0.98 µg L-1 (Cu), 0.65 µg L-1 (Cd), 0.57 µg L-1 (Pb), 1.12 µg L-1 (Co), 1.82 µL-1 (Cr), 1.67 µg L-1 (Ni) and 0.55 µg L-1 (Mn). Certified reference materials were used to test the validation of the present method. The new solid phase extraction method was successfully applied to determination of the amount of multiple elements in food and beverage samples.

A simple, rapid and green ultrasound assisted and ionic liquid dispersive microextraction procedure for the determination of tin in foods employing ETAAS.

This paper proposes a simple, rapid and green ultrasound assisted and ionic liquid dispersive microextraction procedure using pyrocatechol violet (PV) as complexing reagent and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide [C6MIM][Tf2N] as ionic liquid for the detection of tin employing electrothermal atomic absorption spectrometry (ETAAS). The optimization step was performed using a two-level full factorial design involving the following factors: pH of the working media, amount reagents, ionic liquid volume and extraction time and the chemometric response was tin recovery. The procedure allowed the determination of tin with limits of detection and quantification of 3.4 and 11.3 ng L-1, respectively. The relative standard deviation was 4.5% for a tin solution of 0.50 µg L-1. The validation method was confirmed by analysis of rice flour certified reference material. The method was applied for the quantification of tin in several food samples. The concentration range found varied from 0.10 to 1.50 µg g-1.

A new separation and preconcentration method for selenium in some foods using modified silica gel with 2,6-diamino-4-phenil-1,3,5-triazine.

A novel and simple solid phase extraction method was improved and recommended for selenium. Silica gel was modified with 2,6-diamino-4-phenil-1,3,5-triazine and characterized by FTIR, SEM and elemental analysis and used adsorbent for column solid phase extraction of selenium ions. The experimental parameters (pH, flow rates, amounts of the modified silica gel, concentration and type of eluent, volume of sample, etc.) on the recoveries of selenium were optimized. Standard reference materials were analyzed for validation of method. The present method was successfully applied to the detection of total selenium in water and microwave digested some food samples with quantitative recoveries (> 95%). The relative standard deviations were<8%. Matrix influences were not observed. The adsorption capacity of modified silica gel was 5.90mgg-1. The LOD was 0.015µgL-1. Enrichment factor was obtained as 50 for the introduced method.

Evaluation of iron and zinc levels in recurrent tonsillitis and tonsillar hypertrophy.

OBJECTIVES: The aim of this study is to look into the roles of iron and zinc metals in etiopathogenesis of recurrent tonsillitis and tonsillar hypertrophy by evaluating the levels of iron and zinc elements in the palatine tonsillar tissue. METHODS: In total, 40 patients who underwent a tonsillectomy to treat recurrent tonsillitis and tonsillar hypertrophy were included in the study. Patients were classified into two groups, recurrent tonsillitis and tonsillar hypertrophy, determined by the results of clinical and histopathological examination. The levels of iron and zinc elements were determined for each tonsillar tissue sample. RESULTS: There was a significant difference in the iron and zinc concentrations (p<0.001) between the tonsillar hypertrophy and recurrent tonsillitis groups. The levels of iron and zinc were significantly lower in the recurrent tonsillitis group. CONCLUSIONS: This study suggests that low tissue concentrations of iron and zinc may lead to recurrent tonsillitis.

Separation and preconcentration of Cu(II), Pb(II), Zn(II), Fe(III) and Cr(III) ions with coprecipitation method without carrier element and their determination in food and water samples.

In this study, Cu(II), Pb(II), Zn(II), Fe(III) and Cr(III) were determined in some food and water samples after development 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) coprecipitation procedure using flame atomic absorption spectrometry (FAAS). Effects of some analytical parameter including pH, sample volume, reagent amount, centrifuge rate and time, etc. on the presented coprecipitation system were studied for the quantitative recoveries of Cu(II), Pb(II), Zn(II), Fe(III) and Cr(III) ions. The influences of matrix ions were examined. The recovery values for analyte ions were calculated ⩾ 95%. The relative standard deviation was found 8.0% and the preconcentration factor was found as 25 for all analyte ions. The detection limits (k=3, N=21) were found to be as 0.80 µg L(-1) Cu(II), 3.08 µg L(-1) Pb(II), 0.28 µg L(-1) Zn(II), 0.91 µg L(-1) Fe(III) and 1.82 µg L(-1) Cr(III). NIST SRM 1515 Apple leaves and GBW-07605 Tea certified reference materials were used to confirm the accuracy of the method. The simultaneous coprecipitation method was applied to various water and microwave digested food samples.

Selective speciation of inorganic antimony on tetraethylenepentamine bonded silica gel column and its determination by graphite furnace atomic absorption spectrometry.

A speciation system for antimony (III) and antimony (V) ions that based on solid phase extraction on tetraethylenepentamine bonded silica gel has been established. Antimony was determined by graphite furnace atomic absorption spectrometry (GF-AAS). Analytical conditions including pH, sample volume, etc., were studied for the quantitative recoveries of Sb (III) and Sb (V). Matrix effects on the recovery were also investigated. The recovery values and detection limit for antimony (III) at optimal conditions were found as >95% and 0.020 µg L(-1), respectively. Preconcentration factor was calculated as 50. The capacity of adsorption for the tetraethylenepentamine bonded silica gel was 7.9 mg g(-1). The validation was checked by analysis of NIST SRM 1573a Tomato laves and GBW 07605 Tea certified reference materials. The procedure was successfully applied to speciation of antimony in tap water, mineral water and spring water samples. Total antimony was determined in refined salt, unrefined salt, black tea, rice, tuna fish and soil samples after microwave digestion and presented enrichment method combination.

Determination of Cd (II), Cu (II), and Pb (II) in some foods by FAAS after preconcentration on modified silica gels with thiourea.

This study describes preconcentration method for determination of Cd (II), Cu (II), and Pb (II) in some food samples. Silica gel was modified with thiourea and characterized by IR and C, H, N, S elemental analysis. Modified silica gel was used as a solid phase extraction for determination of Cd (II), Cu (II) and Pb (II) in tuna fish, biscuit, black tea, rice, kasar cheese, honey, tomato paste, and margarine samples. The analytical conditions including eluent type, pH of sample solutions, flow rates of sample and eluent solutions, etc. were optimized. The influence of the matrix ions on the involvement of the Cd (II), Cu (II), and Pb (II) were also studied. GBW 07605 tea standard reference material was used for validation of method. The method was successfully applied for the determination of Cd (II), Cu (II), and Pb (II) ions in food samples. The detection limits were in the range of 0.81 µg/L, 0.38 µg/L, and 0.57 µg/L for cadmium, copper and lead, respectively. The relative standard deviations of the procedure were below 10%. The sorption capacities were found as 92 µmol/L Cd (II), 286 µmol/L Cu (II), and 121 µmol/L Pb (II).

The relation between keratoconus and plasma levels of MMP-2, zinc, and SOD.

PURPOSE: To evaluate the levels of matrix metalloproteinase-2 (MMP-2), superoxide dismutase (SOD), and zinc in plasma taken from patients with keratoconus and to investigate the likely association between these factors and keratoconus. METHODS: A total of 36 patients with keratoconus and 40 control subjects at the Department of Ophthalmology, Faculty of Medicine, Gaziosmanpasa University, were included in the study. Plasma levels of zinc were determined with atomic absorption spectrometry for all the subjects. Measurements of plasma MMP-2 levels were performed by the enzyme-linked immunosorbent assay method. Total plasma (Cu/Zn and Mn) SOD activity was also determined photometrically. RESULTS: The plasma concentrations of zinc and MMP-2 were significantly lower in patients with keratoconus than in the healthy controls (P < 0.001). Total plasma SOD levels were significantly higher in patients with keratoconus than in the healthy controls (P < 0.001). CONCLUSIONS: We detected reduced plasma levels of zinc and MMP-2, and enhanced plasma levels of SOD in patients with keratoconus compared with the healthy subjects. The data presented provide insight into the potential role these molecules may play in the etiopathogenesis of this disease.

Evaluation of iron, zinc, and copper levels in pterygium tissue.

PURPOSE: To determine the concentration of the trace elements iron, copper, and zinc in pterygium tissue and healthy conjunctiva tissue and to investigate the involvement of these elements in pterygium etiopathogenesis. METHODS: Twenty patients with pterygium were enrolled in the study. The pterygium was excised and a conjunctival rotational flap or autograft inserted. Normal conjunctiva tissue was obtained from the flap or graft. The concentrations of iron, zinc, and copper in the pterygium and conjunctiva tissues were determined by atomic absorption spectrometry after microwave digestion. RESULTS: Iron, zinc, and copper levels were significantly higher in the pterygium tissue than in the normal conjunctiva (P < 0.001). The mean iron, zinc, and copper concentrations in the pterygium tissue were 819, 214, and 3.40 µg/g, whereas the mean concentrations of these elements in the control tissue were 491, 148, and 2.19 µg/g, respectively. CONCLUSIONS: Pterygium is a fibrovascular proliferative disorder and elevated levels of trace elements in pterygium tissue may play a pathogenic role via oxidative damage.

Assessment of trace elements in animal tissues from Turkey.

In this study, trace element contents of animal tissues were determined by atomic absorption spectrometry after microwave digestion method. The accuracy of the method was confirmed by analysis of standard reference material (NIST SRM 1577b Bovine Liver). Trace element contents in animal tissue samples were found in the range of 98.3-18.2 µg/g (Fe), 2.89-0.26 µg/g (Mn), 23.9-4.54 µg/g (Zn), 0.08-0.01 µg/g (Pb), 32.9-1.66 µg/g (Cu), and 0.32-0.01 µg/g (Cd). The results were compared with literature values. The results obtained for toxic and trace elements in analyzed animal tissue samples were acceptable to human consumption at nutritional and toxic levels.

Determination of As(III) and As(V) species in some natural water and food samples by solid-phase extraction on Streptococcus pyogenes immobilized on Sepabeads SP 70 and hydride generation atomic absorption spectrometry.

The speciation of arsenic(III) and arsenic(V) by using Streptococcus pyogenes immobilized on Sepabeads SP 70 resin has been investigated with solid-phase extraction method. The arsenic levels were determined hydride generation atomic absorption spectrometry (HGAAS) in sample solutions. The procedure presented based on quantitative recoveries of As(III) as >95%. Also the As(V) recoveries were obtained as <5% using the presented method. After reduction of As(V) by using KI and ascorbic acid and waiting 1h later, the system was applied to determination of total arsenic. As(V) was found as the difference between the total As and As(III) content. Various experimental parameters such as pH, amount of microorganism, sample volume, etc. were investigated. The capacity of biosorbent for arsenic(III) was calculated as 7.3 mg/g. The preconcentration factor was found as 36. The relative standard deviation was calculated below 8%. Limit of detection was calculated as 13 ng/L. The validation of the presented procedure was tested by analysis of standard reference materials (NIST SRM 1568a Rice floor and GBW 07605 Tea) and obtained fairly compatible results. The procedure was also successfully applied to arsenic speciation and determination of some natural water and food samples.

Determination of trace metals in different fish species and sediments from the River Yesilirmak in Tokat, Turkey.

In the presented study, five different fish species and sediment samples were collected from polluted areas, control samples from unpolluted areas in Yesilirmak River during 2008-2009. The samples were analyzed using flame and/or graphite furnace atomic absorption spectrometry after various digestion methods. The relative standard deviations (RSD) were found below 10%. The accuracy of the methods was confirmed by certified reference materials. The maximum iron, zinc, copper, lead, manganese, nickel and cadmium concentrations were found to be as 116 (Fe), 63.5 (Zn), 2.5 (Cu), 0.56 (Pb), 9.4 (Mn), 10.2 (Ni) and 0.75 (Cd) microg/g in fish samples. The maximum metal concentration in sediment was 3566 microg/g for Fe, 463 microg/g for Mn, 45.5 microg/g for Zn, 38.7 microg/g for Cu, 17.3 microg/g for Pb, 79.2 microg/g for Ni and 0.55 microg/g for Cd, respectively. Some species is accumulated trace metals at high ratio.

Seasonal investigation of trace element contents in commercially valuable fish species from the Black sea, Turkey.

Fish species (Sarda sarda, Mulus barbatus ponticus, Trachurus trachurus and Merlangius merlangus) were collected from the Black sea, Turkey between 2008 and 2009 (spring, summer, autumn and winter). The samples were analyzed using flame and graphite furnace atomic absorption spectrometry after microwave digestion. The maximum metal concentrations were found to be as 25.5-41.4 microg/g (Fe), 17.8-25.7 microg/g (Zn), 0.28-0.64 microg/g (Pb), 0.64-0.99 microg/g (Cr), 1.3-3.6 microg/g (Mn), 1.4-1.9 microg/g (Cu), 0.18-0.35 microg/g (Cd) and 0.25-0.42 microg/g (Co) for fish species. The concentration of trace metals in samples is depended on fish species. Some species is accumulated trace metals at high ratio. Trace element levels in analyzed fish species were acceptable to human consumption at nutritional and toxic levels. The levels of lead and cadmium in fish samples were higher than the recommended legal limits.

Coprecipitation of trace elements with Ni2+/2-Nitroso-1-naphthol-4-sulfonic acid and their determination by flame atomic absorption spectrometry.

Ni(2+)/2-Nitroso-1-naphthol-4-sulfonic acid precipitate was used for the coprecipitation of Co, Pb, Cu, Fe and Zn prior to their flame atomic absorption spectrometric (FAAS) determinations in environmental samples. The precipitate could be easily dissolved with concentrated nitric acid. The recovery values for analyte ions were higher than 95%. The parameters including pH, sample volume, centrifuge time, amounts of nickel and matrix effects were optimized for the quantitative recoveries of the analytes. The relative standard deviations of cobalt, lead, copper, iron and zinc were found 4.5, 5.7, 3.8, 6.1 and 7.5%, respectively. The limit of detection was calculated as 1.05, 2.67, 1.30, 1.38, and 0.50 microg L(-1) for cobalt, lead, copper, iron and zinc. The validation of the procedure was checked by the analysis of IAEA 336 lichen and SLRS 4 Riverine water standard reference materials were analyzed with satisfactory results. The presented coprecipitation procedure was successfully applied to some environmental samples for determination of analyte ions.

3-Ethyl-4-(p-chlorobenzylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-one (EPHBAT) as precipitant for carrier element free coprecipitation and speciation of chromium(III) and chromium(VI).

A method for the separation and speciative determination of Cr(VI) and Cr(III) has been developed. The procedure is based on coprecipitation of Cr(III) on 3-ethyl-4-(p-chlorobenzylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-one (EPHBAT) without carrier element. The Cr(III) can be selectively precipitated on EPHBAT in the pH range of 8.0-9.0, while Cr(VI) cannot be retained. Total chromium was determined after the reduction of Cr(VI) to Cr(III) with 0.5 mL of concentrated H2SO4 and 0.5 mL of ethanol. Cr(VI) concentrations were obtained as the respective differences between total chromium and Cr(III). Experiments were performed to optimize conditions, such as pH, amounts of EPHBAT, sample volume, etc. A preconcentration factor of 50-fold was achieved for Cr(III). The detection limit of the method for Cr(III) was 1.0 microg L(-1). To validate the developed method, the certified reference materials (NIST SRM 1573a and GBW 0703) were analyzed. The method was applied for the speciation of chromium in spiked natural water samples with satisfactory results.

Biosorptive removal of mercury(II) from aqueous solution using lichen (Xanthoparmelia conspersa) biomass: kinetic and equilibrium studies.

The potential use of the lichen biomass (Xanthoparmelia conspersa) to remove mercury(II) ions from aqueous solution by biosorption was evaluated using the batch method. Effects of pH, contact time, biomass concentration and temperature on the removal of Hg(II) ions were studied. The Langmuir isotherm models defined the equilibrium data precisely compared to Freundlich model and the maximum biosorption capacity obtained was 82.8 mg g(-1). From the D-R isotherm model, the mean free energy was calculated as 9.5 kJ mol(-1). It shows that the biosorption of Hg(II) ions onto X. conspersa biomass was taken place by chemical ion-exchange. Experimental data were also performed to the pseudo-first-order and pseudo-second-order kinetic models. The results indicated that the biosorption of Hg(II) on the lichen biomass followed well the second-order kinetics. Thermodynamic parameters, DeltaG(o), DeltaH(o) and DeltaS(o) indicated the Hg(II) sorption to be exothermic and spontaneous with decreased randomness at the solid-solution interface. Furthermore, the lichen biomass could be regenerated using 1M HCl, with up to 85% recovery, which allowed the reuse of the biomass in ten biosorption-desorption cycles without any considerable loss of biosorptive removal capacity.

Arsenic speciation in natural water samples by coprecipitation-hydride generation atomic absorption spectrometry combination.

A speciation procedure for As(III) and As(V) ions in environmental samples has been presented. As(V) was quantitatively recovered on aluminum hydroxide precipitate. After oxidation of As(III) by using dilute KMnO(4), the developed coprecipitation was applied to determination of total arsenic. Arsenic(III) was calculated as the difference between the total arsenic content and As(V) content. The determination of arsenic levels was performed by hydride generation atomic absorption spectrometry (HG-AAS). The analytical conditions for the quantitative recoveries of As(V) including pH, amount of aluminum as carrier element and sample volume, etc. on the presented coprecipitation system were investigated. The effects of some alkaline, earth alkaline, metal ions and also some anions were also examined. Preconcentration factor was calculated as 25. The detection limits (LOD) based on three times sigma of the blank (N: 21) for As(V) was 0.012 microg L(-1). The satisfactory results for the analysis of arsenic in NIST SRM 2711 Montana soil and LGC 6010 Hard drinking water certified reference materials for the validation of the method was obtained. The presented procedure was successfully applied to real samples including natural waters for arsenic speciation.

Assessment of trace metal levels in some moss and lichen samples collected from near the motorway in Turkey.

In this study, 14 different lichen and moss samples were collected from near the Sivas-Tokat motorway (5-25 m), control samples were collected from uncontaminated locations (1000-3000 m) during 2005. Samples were analyzed using flame and graphite furnace atomic absorption spectrometry after microwave digestion. The maximum metal concentrations were found to be as 468.1 microg/g (Fe), 270.5 microg/g (Mn), 67.6 microg/g (Zn), 53.3 microg/g (Pb), 79.6 microg/g (Ni), 33.9 microg/g (Cr), 29.6 microg/g (Cu) and 5.7 microg/g (Cd) for mosses, 455.5 microg/g (Fe), 170.5 microg/g (Mn), 77.6 microg/g (Zn), 6.5 microg/g (Pb), 10.1 microg/g (Ni), 3.8 microg/g (Cr), 25.6 microg/g (Cu) and 1.5 microg/g (Cd) microg/g for lichens. The concentration of trace metals in samples is depended on moss and lichen species. Some species is accumulated trace metals at high ratio.

Biosorption of palladium(II) from aqueous solution by moss (Racomitrium lanuginosum) biomass: equilibrium, kinetic and thermodynamic studies.

The biosorption potential of Racomitrium lanuginosum as aquatic moss biosorbent for the removal of Pd(II) from aqueous solution was investigated. The effects of pH, biomass dosage, contact time, and temperature on the biosorption processes were systematically studied. Experimental data were modeled by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. Langmuir isotherm model (R(2)=0.994) fitted the equilibrium data better than the Freundlich isotherm model (R(2)=0.935). The monolayer biosorption capacity of R. lanuginosum biomass for Pd(II) was found to be 37.2mg/g at pH 5. The mean free energy was calculated as 9.2 kJ/mol using the D-R isotherm model (R(2)=0.996). This result indicated that the biosorption of Pd(II) was taken place by chemical ion-exchange. The calculated thermodynamic parameters, DeltaG degrees , DeltaH degrees and DeltaS degrees showed that the biosorption of Pd(II) on R. lanuginosum biomass was feasible, spontaneous and exothermic under examined conditions. Experimental data were also tested using the biosorption kinetic models. The results showed that the biosorption processes of Pd(II) on R. lanuginosum followed well pseudo-second-order kinetics at 20-50 degrees C (R(2)=0.999).

Characterization of biosorption process of As(III) on green algae Ulothrix cylindricum.

Arsenic (As) is generally found as As(III) and As(V) in environmental samples. Toxicity of As(III) is higher than As(V). This paper presents the characteristics of As(III) biosorption from aqueous solution using the green algae (Ulothrix cylindricum) biomass as a function of pH, biomass dosage, contact time, and temperature. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the biosorption isotherm of As(III) by U. cylindricum biomass. The biosorption capacity of U. cylindricum biomass was found as 67.2mg/g. The metal ions were desorbed from U. cylindricum using 1M HCl. The high stability of U. cylindricum permitted 10 times of adsorption-elution process along the studies with a slightly decrease about 16% in recovery of As(III) ions. The mean free energy value evaluated from the D-R model indicated that the biosorption of As(III) onto U. cylindricum biomass was taken place by chemical ion-exchange. The calculated thermodynamic parameters, DeltaG degrees , DeltaH degrees and DeltaS degrees showed that the biosorption of As(III) onto U. cylindricum biomass was feasible, spontaneous and exothermic under examined conditions. Experimental data were also tested in terms of biosorption kinetics using pseudo-first-order and pseudo-second-order kinetic models. The results showed that the biosorption processes of As(III) followed well pseudo-second-order kinetics.