Güzin Alpdoğan
Yıldız Technical University
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Publication
Featured researches published by Güzin Alpdoğan.
Analytical Letters | 2006
Bürge Aşçı; Güzin Alpdoğan; Sidika Sungur
Abstract A method was established for enrichment of trace levels of Co(II), Ni(II), Fe(II), and Cu(II) ions in aqueous solutions. These metals were quantitatively retained on an Amberlite XAD‐4 column, after complexation with di‐2‐pyridyl ketone thiosemicarbazone (DPKT). After elution with 1 M HNO3 in acetone, concentration of metals were measured by atomic absorption spectrometry. The effect of major cations of drinking and tap water samples on the sorption of metal ions also were investigated. The amount of the analyte metal ions determined after preconcentration was basically in agreement with the added amount. The developed method was used for the determination of trace amounts of metal ions in drinking and tap water samples with good results, such as relative standart deviations below 2% (N=6) and recoveries greater than >95%.
Analytical Letters | 2002
M. Üstün Özgür; Güzin Alpdoğan; İkbal Koyuncu
ABSTRACT A classic analytical problem is the simultaneous determination of two or more compounds in the same sample without previous chemical separation. In this way derivative spectrophotometry is an anaytical technique of great utility and offers greater selectivity than normal spectrophotometry. The resolution of binary mixtures of compounds with overlapped spectra by derivative spectrophotometry is frequently made on the basis of zero-crossing measurements. A very simple spectrophotometric method using measurements at zero-crossing wavelength is described for resolving binary mixtures of the synthetic colorants sunset yellow (E-110) and erythrosine (E-127). The assay procedure for E-110 and E-127 in Premarin tablets involves extraction of the colorants from tablets with distilled water and measurement of first derivative absorbance values at 482.7 nm for E-127, then filtration from rough paper and measurement of 1D values at 526.3 nm for E-110. Linear correlations over the concentration ranges of 2.0–10.0 µg mL−1 for E-110 (r = 0.9997) and for E-127 (r = 0.9999) were obtained. Commercially available tablets containing E-110 and E-127 were analysed by the proposed method and the HPLC method. Mean values and standard deviations calculated from seven determinations were 122.5 µg/tablet (RSD = 1.9) of E-110, 119.3 µg/tablet (RSD = 2.3) of E-127 for the proposed method and 124.3 µg/tablet (RSD = 0.98) of E-110, 120.9 µg/tablet (RSD = 1.2) of E-127 for the HPLC method. The statistical evaluations indicated that there was no significant difference between the mean values and precisions of the two methods at 95% confidence level (t = 1.68 and 0.24; F = 3.76 and 3.67). This method was satisfactorily used for determining synthetic mixtures of these dyes in different ratios. The avarage percentage recoveries are 105.8% and 102.8% for E-110 and E-127 respectively.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | 1999
Güzin Alpdoğan; Sidika Sungur
Abstract Sensitive and specific atomic adsorption spectroscopy (AAS) and spectrophotometric methods have been developed for the determination of beta adrenergic blocking drug, metoprolol tartrate.The method is based on the formation of Cu(II) dithiocarbamate complex by derivatization of the secondary amino group of metoprolol with CS 2 and CuCl 2 in the presence of ammonia.The copper-bis(dithiocarbamate) complex was extracted into chloroform and the concentration of metoprolol tartrate was determined directly by spectrophotometric and indirectly by AAS measurement of copper.The two methods developed were applied to the assay of metoprolol tartrate in commercial tablet formulations.The methods were compared statistically with each other and with the high performance liquid chromatography (HPLC) method of USPXXII using t - and F -tests.
Analytical Letters | 1999
Güzin Alpdoğan; Sidika Sungur
ABSTRACT An Indirect AAS method has been developed for the determination of analgesic-inflammatory drugs, mefenamic acid, flufenamic acid and diclofenac sodium. The method depends on the complexation with copper (II) ammine sulphate. The complex was extracted into chloroform and the concentrations of substances were determined indirectly by AAS measurement of copper, after re-extraction into 0.3 N nitric acid solution. The developed method was applied to the assay of the drug substances in commercial tablet formulations. The results were statistically compared with those obtained by HPLC method by t- and F-tests at 95% confidence level. Calculated t and F values were both lower than the table values.
Toxicological & Environmental Chemistry | 2016
Güzin Alpdoğan
A multi element preconcentration procedure for solid phase extraction on Amberlite XAD-4 as their salicylaldehyde benzoylhydrazone chelates and flame atomic absorption spectrometric determination of some trace metal ions in water samples are proposed in this work. The influences of some analytical parameters, including pH of aqueous solution, amounts of reagent, flow rates of sample and eluent solutions, and sample volume on the quantitative recoveries of copper, nickel, cobalt, and iron were investigated. The effects of concomitant ions on the retentions of the analytes were also examined. The developed method has been successfully applied to the determination of metal ions in some real samples, including, tap water, river water, spring water, and waste water.
Reviews in Analytical Chemistry | 2007
Fatma Aytan; Güzin Alpdoğan; Sidika Sungur
Lisinopril, a new drug substance, is an angiotensin-converting enzyme (ACE) inhibitor. In this study, we investigate the high pressure liquid chromatographic pH effect on the solution stability of lisinopril. Lisinopril solutions of 75 pg/ml were prepared in various buffer solutions in the range of pH = 2-8. These solutions were heated in an oven at 80°C for various hours. After these periods the solutions were removed and cooled immediately. Then, ΙΟμΙ of the solution was injected into a high pressure liquid chromatographic system containing a Bondapak C18 reversed phase column and a variable wavelength UV visible absorbance detector. The separation was performed with pH = 5 phosphate buffer acetonitril triethylamine (90 : 10 : 0.1) mixture as isocratic mobile phase. The detector was operated at 209 nm. The investigation of the chromatograms and lisinopril peak areas indicated that pH has a significant effect on the stability of lisinopril in aqueous solution and decomposition rate of lisinopril is increased by the decreasing pH. Pseudo first order rate constants were calculated using the time log (peak area) plots. * Corresponding author e-mail : [email protected]
Analytical Letters | 2010
Hale Berber; Güzin Alpdoğan; Bürge Aşçı; Hüseyin Yıldırım; Sidika Sungur
Crosslinked glycidylmethacrylate-methylmethacrylate-divinylbenzen (GMA-MMA-DVB) microspheres were prepared by suspension polymerization. The GMA-MMA-DVB microspheres with an average size of 150–300 μm and surface area of 1.51 m2g−1 were functionalized with 2-aminothiazole (ATAL). The affinity of the functionalized microspheres for copper, iron, aluminum, lead, cobalt, and nickel ions was examined. The effects of pH, resin amount, shaking time, type, and volume of the elution solution on the sorption and desorption properties of functionalized microspheres for these metal ions were investigated using the batch method. Sorption capacities (0.97–1.12 mmolg−1), quantitation limits (2.6–3.0 ppb) and recoveries (90–99%) were calculated.
Analytical Letters | 1997
Güzin Alpdoğan; Sidika Sungur
Abstract An HPLC method has been developed for the determination of the beta adrenergic blocking drug metoprolol tartrate. The method is based on the formation of a Cu (II) - dithiocarbamate complex by precolumn derivatization of secondary amino group of metoprolol with CS2 and CuCl2 in the presence of ammonia. The complex is extracted into chloroform and injected into the chromatograph. Chromatographic separation was performed by a RP (μ Bondapak C18) column with methanol - pH 5.8 phosphate buffer (80 : 20) as the isocratic mobile phase. A variable wavelength absorbance detector (λ = 275 nm) was used. A linear relationship was obtained between peak areas and metoprolol tartrate concentrations over the range of 35 - 180 nmol ml−1. The method was applied to the analysis of metoprolol tartrate tablets and the results were statistically compared with those obtained by official method using t - and F - tests.
Journal of Chemistry | 2016
Güzin Alpdoğan; Nevim San; Şule Dinç Zor
A new procedure for separation and preconcentration of trace amounts of Cu(II), Ni(II), Fe(III), Zn(II), Cr(III), Cd(II), and Pb(II) in fish samples was proposed. The procedure is based on the adsorption of these metal ions on the column of Amberlite XAD-7 as congo red complexes prior to their determination by flame atomic absorption spectrometry (FAAS). Several factors that can affect the sorption and elution efficiency of the metal ions were investigated and optimized. The sorption was quantitative in the pH range of 6.0–9.0 for Cu(II) and Ni(II), 5.5–8.0 for Fe(III), 6.0–8.5 for Zn(II) and Cd(II), and 7.0–8.5 for Cr(III) and Pb(II). The optimum pH for simultaneous retention was 7.5. The sorption capacity of the resin was found to be 0.89, 0.72, 0.82, 0.61, 0.53, 0.84, and 0.78 mg/g for Cu(II), Ni(II), Fe(III), Zn(II), Cr(III), Cd(II), and Pb(II), respectively. The precision of the method was evaluated as the relative standard deviation obtained by analyzing a series of six replicates and below 6% for all seven elements. The validation of the method was performed by the analysis of certified reference materials. The proposed method was successfully applied to separation/preconcentration and determination of these metals in fish samples.
Journal of AOAC International | 2017
Güzin Alpdoğan; Şule Dinç Zor
In this study, dispersive liquid-liquid microextraction coupled with HPLC with variable-wavelength detection was applied for the simultaneous determination of Al, Fe, Cu, and Pb in various water samples at trace levels. In the proposed method, all the system parameters in both the extraction and separation/determination steps, such as extraction and disperser solvent type and their volumes, complexing reagent concentration, salt addition, extraction and centrifugation times, and pH, were optimized to get not only high extraction efficiency but also lower LODs for the analytes. Hematoxylin was used as a complexing reagent, and carbon tetrachloride and methanol were chosen as the extraction and disperser solvents, respectively. Metal complexes were separated with a reversed-phase C18 column by isocratic elution, with methanol-tetrahydrofuran-water (20 + 12 + 68, v/v/v) as the mobile phase at a flow rate of 1.0 mL/min and detection at 575 nm. The accuracy of the method was checked by a Standard Reference Material of water (SRM 1643e), and the recovery values for the analytes were found in the range of 95.6-101.3%. Under the optimum conditions, the developed method was applied to tap water, bottled mineral water, lake water, and seawater for the accurate and sensitive determination of the analytes of interest.
