Nuket Kartal Temel

A micellar sensitized kinetic method for quantification of low levels of bisphenol A in foodstuffs by spectrophotometry

In the current study, because of its potential to leach out into foodstuffs as a result of food contact uses, a new kinetic method for the monitoring and determination of bisphenol A in foods by spectrophotometry for a fixed-time method of 5.0 min at 447 nm was established without a prior preconcentration step. The method is based on selective and rapid reduction of oxalate stabilized-Mn(III) with trace amounts of bisphenol A in the presence of cationic surfactants, CPC and CTAB, as both counter ion and sensitivity enhancer at pH 5.5 and 6.0, respectively. The effects of pH, concentration of reactants, reaction time, reaction temperature, and matrix components on the analytical signal were evaluated in detail, and the optimal conditions were established. There was a good linear relationship in the ranges of 2–120 μg L−1 and 5–200 μg L−1 with detection limits of 0.58 μg L−1 and 1.46 μg L−1 for CPC and CTAB, respectively. The method was validated by using two spiked quality control samples in linear working range. The samples were analyzed with a minimum 3-point calibration around the method quantification limit to minimize matrix effect. The kinetic method was successfully applied to the quantification of trace bisphenol A in the selected food samples, the intra-day and inter-day precisions as a result of stabilization of PVA were lower than 6.0% (as RSD%, n: 5), and the recoveries were quantitatively higher than 93.5% for the two quality control samples spiked with 10, 30 and 50 μg L−1 with satisfactory results.

Using Safranin T as a Charge Transfer-Sensitive Ion-Pairing Reagent in Ultrasound-Assisted Cloud Point Extraction: Determination of Bisphenol A in Selected Beverages

In this study, a new ultrasonic-assisted cloud point extraction method coupled with spectrophotometry was developed to extract from and determine bisphenol A (BPA) in a sample matrix. The method is based on charge transfer-sensitive ion-pairing complex formation between BPA and Safranin T in the presence of nitrate in a micellar interface at pH 5.0. The variables affecting extraction efficiency were optimized. A good linear relationship with a significant sensitivity difference was obtained in the ranges of 2-40 and 2-120 µg/L with LODs of 0.54 and 0.38 µg/L after preconcentration with two different extractants, respectively. From a preconcentration of a 15 mL sample, a preconcentration factor of 60 was obtained. Due to the lack of a certified material compatible with the sample matrix, the method was validated by conducting intraday and interday accuracy and precision studies based on two spiked QC samples (with a recovery rate greater than 94% and an RSD ranging from 3.8 to 5.9%). Moreover, the beverage samples were analyzed by the standard addition method to control for possible matrix effects. BPA was detected in the range of 1.8-7.2 µg/L in beverages with Triton X-114, whereas the levels changed to a range of 1.8-7.3 µg/L with Triton X-45. In such a way not to create a threat, these levels were considerably lower than the specific migration limit set by the European Union.

Katalitik Kinetik Spektrofotometri ile Çevresel Örneklerde Eser Miktarlardaki Toplam Fe'nin Fe(II) Olarak Belirlenmesi

Yontem, Coomassie Brillant Blue 2R’nin bromat ile oksidasyonuna, aktivator olarak 1,10-fenantrolin varliginda demir (II) iyonlarinin secici katalitik etkisine dayanir. Katalitik tepkime yaklasik 3 dakikalik sabitlenmis-zaman yaklasimi ile 520 nm’de spektrofotometrik olarak izlenmistir. Uygulama kosullarinin optimizasyonu arastirilmistir. Elde edilen optimalkosullar: 1.5 mL Coomassie Brillant Blue 2R (1.0 × 10 -4 mol L -1 ), 0.6 mL bromat (0.01 mol L -1 ), 1.5 mL 1,10-fenantrolin (1.0 × 10 -3 mol L -1 ), 25 o C tepkime sicakligi and pH 2.0 de, 520 nm’de 3 dakikalik tepkime zamanidir. Onerilen yontem, 0.0141 mg L -1 ve 0.047 mg L -1 lik secme ve nicellestirme siniri ile 0.05-5 mg L -1 araliginda demir (II)’nin tayinine izin verir. 0.2 ve 3 mg L -1 demir (II)’nin bes tekrarli analizi icin elde edilen bagil standart sapma degerleri sirasiyla %3.8 ve %2.3 tur. Yontem, pH 4.0 ve 40 o C’de sulfit ile demir (III)’un demir (II)’ye on indirgenmesi sonrasi demir eksikligi tedavisinde kullanilan farmasotik ornekler (ferrosolanol ve maltoz gibi) ve gol, nehir ve kuyu suyu gibi bazi cevresel yuzey sularinda toplam demir tayininde uygulanmis, olasi ornek matriks etkisi icin yas asitle cozme sonrasi standart eklemeye dayanan analizle %98.7-102.7 araliginda degisen kantitatif gerikazanimlar elde edilmistir.

Catalytic spectrophotometric determination of trace Mo(VI) in milk-based beverages in the presence of bromophenol blue and H2O2 using SDS as a sensitizer

A simple and low-cost catalytic spectrophotometric method using sodium dodecyl sulfate (SDS) as a sensitivity-improving surfactant to detect low levels of Mo(VI) in beverage matrices was developed. The method is based on the catalytic effect of molybdenum on the oxidation of 4,4′-(1,1-dioxido-3H-2,1-benzoxathiole-3,3-diyl)bis(2,6-dibromophenol) (bromophenol blue, HIn−) with H2O2 in the presence of SDS as a sensitizer in the premicellar region at pH 6.0. The surfactant-sensitive catalytic reaction was monitored by measuring the decrease in the absorbance at 590 nm after a fixed time of 5 min, which is linearly related to the molybdenum concentration in a wide working range. The optimal reaction conditions (e.g., surfactant concentration, reagent concentration and time) were evaluated and optimized, and then the analytical figures of the merit of the method (such as the limits of detection and quantification, linear working range, accuracy and precision) were established. Linearity was observed in a Mo(VI) ion concentration range of 5–150 μg L−1, and the limits of detection and quantification of the method were 1.80 and 5.46 μg L−1, respectively. The relative standard deviations (RSDs) and relative errors for the five replicate measurements of 25 and 100 μg L−1 Mo(VI) were lower than 3.5% and 2.3%, respectively. The interference effect of some anions, cations and neutral species was also tested. The accuracy was controlled by the analysis of two certified samples, and the results were found statistically to be in good agreement with the certified values at a 95% confidence limit. The method was successfully applied to the catalytic determination of low levels of Mo(VI) in milk-based beverages.

Photocatalytic Decolourization of Bromophenol Blue in Aqueous Solution with Cu(II)-Peroxo Complexes in Presence of SDS

Abstract In the current work, the photocatalytic decolourization of Bromophenol blue (BrPB) with Cu(II)-peroxo complexes in presence of sodium dodecyl sulfate (SDS) under UV light was investigated. The analytical parameters such as pH, titanium dioxide (TiO2) catalyst dosage, initial concentration of the dye, amounts of H2O2, Cu(II) and SDS affecting the photocatalytic decolourization of BrPB were studied. The obtained optimal values were as follows: pH 6.0, 55 mmol L-1 H2O2, 60 μg L-1 Cu(II), 0.02 mmol L-1 SDS, 5 mg L-1 dye, 1.0 g L-1 TiO The percent removals have been obtained as 81.6% and 76.3% for TiO2 -UV-H2O2-Cu(II) system with and without SDS while they are 74.3% and 66.2% for TiO2-UV system with and without H2O2 under the optimized conditions. Consequently, it has been observed that the maximum removal rate is obtained for TiO2 -UV-H2O2-Cu(II) in presence of SDS at premicellar region with a value of 81.6%. The removal rate of the dye was monitored by measuring the absorbance at 592 nm, using UV-visible spectrophotometer.