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Öğe A New Analytical Method for the Kinetic Spectrophotometric Determination of Trace Amounts of Nitrite in Some Environmental Water Samples(Modestum Ltd, 2010) Gurkan, Ramazan; Ulusoy, Halil Ibrahim; Akcay, MehmetNitrite is a characteristic pollutant ion, which is ubiquitous within environmental and physiological systems, and occurs in water as an intermediate during the nitrogen cycle. Therefore, the detection and determination of its concentration at trace levels is extremely important in biological and environmental studies. A simple, sensitive and rapid kinetic spectrophotometric method for the determination of nitrite in different natural and wastewater samples is presented. The reaction is initiated by adding the known volumes of a nitrite ion solution of identified concentration to acid solutions of Cresyl violet perchlorate, which the color of indicator reagent changes to yellow with time. Then, the absorbance changes are monitored spectrophotometrically at lambda(max) = 585 nm for the concentration range of 0.01-2 mu g mL(-1) and at lambda(max)= 409 nm for the concentration range of 0.5-5 mu g mL(-1) of nitrite ion at 40 degrees C. The detection limit and quantification limit of the proposed kinetic method were 0.00627 and 0.0188 mu g mL-1 respectively. The RSDs for the determination of 0.2 and 1.5 mu g ml(-1) of nitrite were 4.98% and 2.08% for five replicate measurements, respectively. The effect of possible interfering ions on the determination of nitrite is described. Many of cations and anions have no interfering effect but Fe3+, Fe2+, Cd2+, I-, N-3(-), WO42-, S-2(-), SO32-and S2O32- ions do interfere. The accuracy and validity of the proposed kinetic method was established by studying recovery of spiked nitrite ion and by parallel determination using a standard method based on diazo-coupling reaction. The method was successfully applied to the determination of nitrite in various natural and wastewater samples.Öğe Dissolution Kinetics of Magmatic Rocks via Ultrasonic Leaching for Calcium, Magnesium and Aluminum(Gazi Univ, 2008) Ozkan, Mehmet Hikmet; Gurkan, Ramazan; Ozkan, Aysun; Akcay, MehmetUltrasound is known to enhance solid-liquid interface reactions. This study deals with the investigation of the dissolution of quartz monzonite from magmatic rock class in hydrochloric acid of 1.0% HCl (v/v) in the presence of ultrasound. Dissolution kinetics of ultrasonic leaching for destructive analysis of a magmatic rock sample was investigated. Various dissolution kinetics parameters such as dissolution order (n), dissolution rate constant (k), initial dissolution rate (r(i)) and maximum dissolution (S-max) were determined as the functions of the mass of sample, the grain size of sample and ultrasonication power for Ca, Mg and Al. The kinetic parameters were evaluated to reflect the quantitative aspect of the magmatic rock dissolution behavior.Öğe Micellar-Sensitized Spectrophotometric Determination of Magnesium in Drinking Water(Iser Publications, 2009) Gurkan, Ramazan; Ulusoy, Halil Ibrahim; Akcay, MehmetA sensitive and relatively selective spectrophotometric method is proposed for the rapid determination of magnesium using Eriochrome black T (EBT) as a complexing agent in the presence of N-cetyl-N, N, N-trimethylammonium bromide (CTAB). The complex formation reaction between EBT and magnesium (II) is instantaneous in presence of NH3/NH4Cl buffer at pH 9.5 after CTAB adds as micellar-sensitized medium and the absorbance as analytical signal remains stable for over 6 h. N-cetyl N, N, N-trimethylammonium bromide as cationic surfactant and Triton X-100 as nonionic surfactant are used for improving the sensitivity and solubility of the analytical system, respectively. The surfactant-sensitizing method allows the determination of magnesium in the concentration range of 0.05-1.2 mu g mL(-1) with a molar absorption coefficient of 8928 L mol(-1) cm(-1) and Sandell's sensitivity of 2.82 ng cm(2-). The method has a detection limit of 0.012 mu g mL- 1 (DL=3S(b)/m) and quantification limit of 0.054 mu g mL-1 (QL=10S(b)/m) at an analytical measurement wavelength of 640 nm with a bathochromic shift of 86 nm. The selectivity of chelating reagent was improved by the use of 1 mL masking agent solution containing 0.1 mol L-1 EDTA, 0.01 mol L-1 triethanolamine and 5000 mu g NaF mL(-1). The proposed method has been successfully applied to the determination of magnesium at trace levels in different drinking water samples. The precision (with CV of 2.35%) and the accuracy obtained were highly satisfactory.Öğe Simultaneous determination of dissolved inorganic chromium species in wastewater/natural waters by surfactant sensitized catalytic kinetic spectrophotometry(Elsevier Science Bv, 2017) Gurkan, Ramazan; Ulusoy, Halil Ibrahim; Akcay, MehmetA simple, rapid, highly accurate and sensitive kinetic method is proposed for determining chromium(VI). The method is based on its catalytic effect on the oxidation of Celestine blue (CB+) by H2O2 in the presence of 2,2'-bipyridyl (Bipyr) and cetylpyridinium chloride (CPC) at pH 6.50. The reaction was monitored spectrophotometrically by measuring the absorbance of indicator dye at 645 nm. The analytical variables, which have influences on the sensitivity, were investigated and the optimum conditions were established. The optimized conditions made it possible to determine and speciate chromium in a linear range of 5-200 mu g L-1 with a detection limit of 0.65 mu g L-1. The recoveries and relative standard deviations (RSDs) for the determination of 10, 25, 75 and 150 mu g L-1 Cr(VI) (n: 5) were in the range of 99.0-99.8% and 0.2-3.5%, respectively. The selectivity was also studied and greatly enhanced by adding a suitable masking mixture. The method was successfully applied to the simultaneous analysis of Cr(III) and Cr(VI) in natural water and waste water samples with a recovery changing in the range of 95-103% for Cr(III) and 100-104% for Cr(VI). Its accuracy was validated by the analysis of certified reference materials with good agreement between certified and found values. (C) 2012 Production and hosting by Elsevier B.V. on behalf of King Saud University.Öğe Simultaneous Determination of Vitamins B1 and B2 in Food Samples by Modified Cloud Point Extraction Method and HPLC-DAD(SPRINGER, 2018) Ulusoy, Songul; Akcay, MehmetA preconcentration and determination method was developed for vitamins B1 (thiamin) and B2 (riboflavin) at trace amounts based on cloud point extraction (CPE) and HPLC analysis. As a new approach in this method, Ag(I) ion was used to increase the transferring of vitamin molecules to micelle medium. Then, the formed complexes between Ag(I) ions and vitamins were easily extracted to nonionic surfactant phase. Following phase separation by centrifugation, aqua phase was separated and then surfactant-rich phase was diluted with 300 mu L of 0.1 M HCl in 50% methanol. Under the optimized conditions, linear calibration curves were obtained in the range of 4-400 ng mL(-1) for thiamin and 1-500 ng mL(-1) for riboflavin. The detection limits of method were calculated as 1.33 and 0.35 ng mL(-1), respectively. The relative standard deviations were 2.90 and 2.20% for five replicate measurements at 100 ng mL(-1) concentration level. The method was validated by the analysis of three certified reference materials (NIST 3280, BCR-485, and ERM-BD600) and recovery test. Finally, the method was applied to the determination of vitamins B1 and B2 in real samples, including baby foods, milk, and cereals.Öğe Simultaneous pre-concentration of Pb and Sn in food samples and determination by atomic absorption spectrometry(SPRINGER, 2013) Ulusoy, Halil Ibrahim; Aksoy, Ummugulsum; Akcay, MehmetA cloud point extraction (CPE) method has been developed for the pre-concentration and simultaneous determination of lead [Pb(II)] and tin [Sn(II)] using Acridine Orange as complexing reagent and mediated by nonionic surfactant (Triton X-114) by flame atomic absorption spectrometry (FAAS). The main factors affecting analytical performance of CPE have been investigated in detail. The extracted surfactant-rich phase was diluted with (1.0 mol L-1) nitric acid in methanol, prior to subjecting FAAS. The calibration graphs obtained from Pb(II) and Sn(II) were linear in the concentration ranges of 5-1,000 and 10-5,000 mu g L-1 with detection limits of 1.40 and 2.86 mu g L-1, respectively. The relative standard deviations for 10 replicates containing 25 mu g L-1 of Pb(II) and Sn(II) were 2.15 and 2.50 %, respectively. The analytical procedure was verified by the analysis of the standard reference materials NWTMDA-61.2 (water-trace elements) and NIST SRM 1548a (typical diet). The developed method has been applied to the simultaneous determination of total Pb and Sn in canned food samples including juices, tomato paste, corn, and green pea.Öğe Thin-Layer Chromatographic Specification and Separation of Cu1+, Cu2+, Ni2+, and Co2+ Cations(OXFORD UNIV PRESS INC, 2010) Savasci, Sahin; Akcay, Mehmet; Ergul, Soner…
