Halil İbrahim Ulusoy

Removal of uranyl ions in aquatic mediums by using a new material: Gallocyanine grafted hydrogel

A new material containing gallocyanine (GC) grafted polyacyril amide (PAA) was synthesized and its adsorption ability was examined for the removal of uranyl ions from aqueous media. The new developed adsorbent was characterized by FTIR, SEM, and PZC analysis. Adsorption of UO₂(2+) ions from aqueous solution as a function of ion concentration, pH, ionic strength, temperature, and reusability of adsorbent was investigated in detail. The adsorption data were analyzed by using the Langmuir, Freundlich and Dubinin-Radushkevich (DR) models. The adsorption of UO₂(2+) increased with pH and reached a plateau value in the pH range 5-6. The adsorption of UO₂(2+) ions were not affected by increasing ionic strength. The adsorption mechanism followed an endothermic and spontaneous process with increased disorderliness at adsorbate/adsorbent interface. The adsorption process followed a pseudo-second-order kinetics. The new developed material is a potential adsorbent for effective removal of uranyl ions from aquatic solutions.

A micellar improved method for trace levels selenium quantification in food samples, alcoholic and nonalcoholic beverages through CPE/FAAS.

A useful preconcentration and determination method was proposed for trace selenium in food samples. The procedure is based on complex formation of Pyronine B with Se(IV) ions in the presence of sodium dodecyl sulphate (SDS) and Ponpe 7.5. The variables affecting complex formation, extraction and phase separation were studied and optimised. Under the experimental conditions used, the calibration graph was linear in the range of 20-1700 μg L(-1) for Se(IV) ions. The limit of detection was 3.81 μg L(-1) of Se(IV) and the relative standard deviation for 5 replicate determinations at 250 μg L(-1) concentration level was 2.45%. Recovery values were obtained between 97.8% and 102.8% for spiked samples. The method was successfully applied to the determination of total selenium in some food samples and alcoholic and nonalcoholic beverages. Its validity was checked by the analysis of four certified reference materials. The results obtained by the proposed method were quantitatively in good agreement with the certified values.

Simple and useful method for determination of inorganic selenium species in real samples based on UV-VIS spectroscopy in a micellar medium

A preconcentration and determination methodology utilizing the cloud point phenomenon was developed for the determination of inorganic selenium species using UV-VIS spectrophotometry. The cloud point extraction method was based on the selective formation of a complex between selenium(IV) ions and 4,5-diamino-6-hydroxy-2-mercapto pyrimidine (DAHMP). Then, the formed stable complex was extracted to a nonionic surfactant phase of Triton X-114. After phase separation was carried out via decantation, the surfactant-rich phase was diluted with 20% ethanol solution and the absorbance signal was measured at 458 nm using an UV-VIS spectrophotometer. Under the optimized conditions, linear calibration curves were obtained over a range of 20–1500 ng mL−1 with detection and quantification limits of 6.06 ng mL−1 and 19.89 ng mL−1, respectively. The relative standard deviation was 2.80% for 5 replicate measurements at 250 μg L−1 concentration level. The proposed method is very versatile and economic as only a conventional spectrophotometer is used for the measurements. The method was validated by the analysis of two certified reference materials and a recovery test. Finally, the method was applied to the determination of the total Se amount in real samples including water samples and hen eggs containing selenium.

A new approach to the determination of folic acid at trace levels: using a Fe(III)-folic acid complex to amplify analytical signal

A fast, efficient, cost-effective, and environmental-friendly analytical methodology was developed for preconcentration and determination of trace folic acid in food samples prior to high performance liquid chromatography with diode array detection (HPLC-DAD). The method is based on formation of stable complexes between folic acid and Fe(III) ions at pH 8.0. The formed complexes were extracted to a nonionic surfactant phase containing PONPE 7.5. The surfactant rich phase (SRP) was separated by decantation and diluted with 300 μL of a mixture of 1 M HCl and methanol at a 1 : 1 ratio. The parameters and variables that affected the method were also investigated and optimized in detail. The limit of detection (LOD) of folic acid was 6.06 ng mL−1, the linear range of quantitation for folic acid was 20–1200 ng mL−1 and the correlation coefficients of the calibration curves were 0.9976. The average recoveries and relative standard deviations in the analysis of real samples were in the range of 95.1–105.1% and 1.73–5.25%, respectively. After validation of the method was carried out, the method was applied to the determination of folic acid in real samples, including baby foods, vegetables, cereals, and pharmaceutical samples.

A Novel Indicator Reaction for the Catalytic Determination of V(V) at ppb Levels by the Kinetic Spectrophotometric Method

A novel sensitive and relatively selective kinetic method is presented for the determination of V(V), based on its catalytic effect on the oxidation reaction of Ponceau Xylydine by potassium bromate in presence of 5-sulfosalicylic acid (SSA) as activator. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of Ponceau Xylydine at 640 nm between 0.5 to 7 min (the fixed time method) in H3PO4 medium at 25oC. The effect of various parameters such as concentrations of H3PO4, SSA, bromate and Ponceau Xylydine, temperature and ionic strength on the rate of net reaction were studied. The method is free from most interferences, especially from large amounts of V(IV). The decrease in absorbance is proportional to the concentration of V(V) over the entire concentration range tested (1-15 ng mL−1) with a detection limit of 0.46 ng mL-1 (according to statistical 3Sblank/k criterion) and a coefficient of variation (CV) of 1.8% (for ten replicate measurement at 95% confidence level). The proposed method suffers few interferences such as Cr(VI) and Hg(II) ions. The method was successfully applied to the determination of V(V) in tap water, drinking water, bottled mineral water samples and a certified standard reference material such as SRM-1640 with satisfactory results. The vanadium contents of water samples were also determined by FAAS for a comparison. The recovery of spiked vanadium(V) was found to be quantitative and the reproducibility was satisfactory. It was observed that the results of the SRM 1640 were in good agreement with the certified value.

A new magnetic nanodiamond/graphene oxide hybrid (Fe3O4@ND@GO) material for pre-concentration and sensitive determination of sildenafil in alleged herbal aphrodisiacs by HPLC-DAD system

A sensitive analytical methodology was investigated to concentrate and determine of sildenafil citrate (SLC) present at trace level in herbal supplementary products. The proposed method is based on simple and sensitive pre-concentration of SLC by using magnetic solid phase extraction with new developed magnetic nanodiamond/graphene oxide hybrid (Fe3O4@ND@GO) material as a sorbent. Experimental variables affecting the extraction efficiency of SLC like; pH, sample volume, eluent type and volume, extraction time and amount of adsorbent were studied and optimized in detail. Determination of sildenafil citrate after magnetic solid phase extraction (MSPE) was carried out by HPLC-DAD system. The morphology, composition, and properties of the synthesized hybrid material was characterized by Fourier transform infrared spectrometry (FT-IR), Raman spectrometry (Raman), X-ray diffraction spectrometry (XRD), scanning electron microscopy (SEM), mapping photographs, zeta potential analyzer, and BET surface area analysis. Under optimized conditions, linear range was ranged from 5.00 to 250.00 ng mL-1 with R2 of 0.9952. The limit of detection (LOD) was 1.49 ng mL-1 and the recoveries at two spiked levels were ranged from 94.0 to 104.1% with the relative standard deviation (RSD) < 7.1% (n = 5). The enhancement factor (EF) was 86.9. The results show that the combination MSPE with HPLC-DAD is a suitable and sensitive method for the determination of SLC in real samples.

Synthesis and characterization of a composite polymeric material including chelating agent for adsorption of uranyl ions

In this study, a versatile polymeric material was synthesized by grafting Calcon Carboxylic Acid (CCA), which is known as a chelating agent for some metal ions, to polyacrylamide (PAA) structure. Thus, the adsorptive properties of inert PAA polymer were significantly improved owing to this procedure. The obtained new material, CCA-g-PAA, was characterized by point zero charge (PZC), FTIR, SEM, and UV-VIS-NIR analysis. The adsorption properties of new material were investigated comprehensively and experimental variables were optimized such as pH, temperature, time, and concentration. Experimental data were evaluated by using theoretical adsorption models. The maximum adsorption capacity of material was calculated as 0.079molkg-1 by considering Langmuir equation. The constants calculated from Freundlich and DR model were found as 6.98 and 0.441, respectively. Adsorption kinetic was also explained with pseudo second order and intra particular diffusion models. Experimental studies were showed that adsorption was endothermic and occurred spontaneously. The developed material has important advantages such as reusability, cost-effective synthesis procedure, high adsorption capacity, and selectivity.

FPSE-HPLC-DAD method for the quantification of anticancer drugs in human whole blood, plasma, and urine

The present work describes a fast, sensitive and selective procedure for the analyses of aromatase inhibitors including anastrozole, letrozole and exemestane used in the treatment of metastatic breast cancer by high performance liquid chromatography (HPLC) in human whole blood, plasma, and urine samples succeeding an extraction by innovative fabric phase sorptive extraction (FPSE). These drugs were successfully determined using a Luna C18 column at 25 °C using acetonitrile and phosphate buffer. The analytical method was validated, using weighted-matrix matched standard calibration curves. The intra- and inter-day accuracy values (precision and trueness) fulfill the criteria of International Guidelines on Bioanalytical Methods Validation. The analytical performances were further tested on real human biological samples. To the best of our knowledge, this is the first FPSE procedure applied to human whole blood, plasma, and urine samples for the concurrent analysis of aromatase inhibitors possessing a wide range of polarity index values and could be easily adopted as a rapid and green analytical protocol for clinical and pharmaceutical applications. The proposed HPLC method is very innovative since in the literature there are only methods dealing with a single antitumoral drug, and no process has been described so far for these three antitumoral drugs together directly from the whole blood.