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    DES-based vortex-assisted liquid-liquid microextraction procedure developed for the determination of paraben preservatives in mouthwashes
    (Elsevier, 2022) Dalmaz, Aslıhan; Ozak, Sezen Sivrikaya
    A green deep eutectic solvent-based vortex-assisted liquid-liquid microextraction (DES-VALLME) procedure for the determination of parabens in mouthwashes was developed. Deep eutectic solvents formed by combining DLmenthol and decanoic acid in different mol ratios were prepared, the highest extraction recovery was obtained with DES consisting of 4:1 M ratio, and this DES was used as an extraction solvent for paraben determination in mouthwashes. The effect of parameters such as solution pH, mol ratio of DES composition, DES volume, vortex and centrifugation time and sample volume were examined. Optimum working conditions of the study; 400 mu L DES, 3 min. vortex time, 5 min. centrifugation time, 5 mL sample volume were determined. The detection limit was in the range of 4.6-6.1 mu g L-1, while the RSDs values were in the range of 0.70-1.41% in intraday and 1.27-2.41% in interday. The method in the study was successfully applied for the determination of methyl, ethyl, propyl and butyl paraben in 10 different mouthwashes obtained from cosmetic stores..
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    Development of clinoptilolite zeolite-coated magnetic nanocomposite-based solid phase microextraction method for the determination of Rhodamine B in cosmetic products
    (Elsevier, 2022) Dalmaz, Aslıhan; Ozak, Sezen Sivrikaya
    Green synthesis of clinoptilolite zeolite/Fe3O4 nanocomposite (MZNC) was carried out using Laurus Nobilis L. leaf extract. Characterization of this MZNC was performed using Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, X-Ray Diffraction and Vibrating Sample Magnetometer. According to the VSM analysis results, the saturation magnetization of 23 emu/g and coercivity of 23.5 Oe indicate that the synthesized magnetic nanocomposite is superparamagnetic. A new ultrasonic assisted clinoptilolite zeolite-coated magnetic nanocomposite-based solid phase microextraction (MZNC-SPME) method com-bined with high performance liquid chromatography was developed for the extraction and determination of Rhodamine B. The preconcentration factor for the MZNC-SPME method was found to be 40 under opti-mal conditions. Under optimal conditions, the linear range, correlation coefficient (R 2 ), limit of detection (LOD), and intra-and interday relative standard deviation (RSD) were found to be 1.0 0-10 0.0 0 ng mL -1, 0.9995, 0.16 ng mL(-1), 1.89% and 2.49%, respectively. The developed method was successfully performed to determine Rhodamine B in 6 different cosmetic samples. 6 ions and 5 different dyes were added to the sample solution to show the selectivity of the method. The obtained results show that the determination of Rhodamine B is possible in the presence of these ions and dyes. In order to determine the accuracy of the MZNC-SPME method, two different concentrations of Rhodamine B concentration in cosmetic sam-ples were added as 10 and 50 ng mL -1. Extraction recoveries were found in the range of 92.03-101.52% and these results are quite satisfactory. It is seen that the developed method for the extraction and deter-mination of Rhodamine B from cosmetic samples is applicable due to the easy synthesis of the sorbent and the short, simple, environmentally friendly and low cost of the method.(c) 2022 Elsevier B.V. All rights reserved.
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    Green synthesis of ZnO nanoparticles using Laurus nobilis L. extract and investigation of corrosion inhibition properties of DES-based nanofluids
    (Springer, 2024) Dalmaz, Aslihan; Kasimfirtina, Eren; Ozak, Sezen Sivrikaya
    In this study, new nanofluids based on four different deep eutectic solvents consisting of acetic acid and ethylene glycol as hydrogen bond acceptors, choline chloride, and water as hydrogen bond donor were prepared and these deep eutectic solvents, ZnO used to influence the corrosion of nanoparticles. The study's originality is that for the first time in this study, ZnO nanoparticles obtained with the help of the green material deep eutectic solvent and the extract of Laurus nobilis L. leaves were used effectively in the corrosion study. As a result of the corrosion studies, the best corrosion prevention efficiency was determined in the nanofluid prepared by adding 0.015% by weight ZnO nanoparticles. According to the XRD analysis results, the synthesized ZnO nanoparticles are formed in a hexagonal structure. When the SEM images of ZnO nanoparticles were examined, it was seen that the obtained structure was homogeneous, and the dimensions of the nanoparticles varied between 12 and 33 nm. The thermal stability of ZnO nanoparticles was proven from the TGA curve, where only a 2% weight loss was observed. ZnO nanoparticles did not undergo any degradation up to 1000(degrees)C.
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    Hydrophilic deep eutectic solvent based microextraction procedure for the determination of four paraben preservatives in vitamin D for babies: A green approach
    (Elsevier, 2023) Akmes, Ali; Dalmaz, Aslihan; Ozak, Sezen Sivrikaya
    In this study, an easily available, sensitive, and fast hydrophilic deep eutectic solvent-liquid phase microextraction method developed using deep eutectic solvent (DES) as a green solvent for the determination and microextraction of paraben (methyl, ethyl, propyl, and butyl) preservatives in vitamin D for babies. The highest yield for extraction recovery was obtained using DES consisting of a 1:4 M ratio of choline chloride and acetic acid. Moreover, various optimization parameters such as DES volume, DES type, sample volume, and centrifugation time were investigated in order to develop a real sample specific microextraction method. Relative standard deviation values were 0.92%-2.87%, the detection limit was 0.194-0.254 & mu;g/mL, and extraction recovery values were between 87.40% and 102.98%. The method developed in this study was successfully applied to 5 different babies in vitamin D for babies obtained from pharmacies for the determination of methyl, ethyl, propyl, and butylparaben. As far as we know, it is the first study conducted both in terms of the determination of paraben preservatives in vitamin D for babies and in terms of the fact that DES used in this study is used for the first time in vitamin D for babies.
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    Ultrasound-assisted hydrophobic deep eutectic solvent based solid-liquid microextraction of Sudan dyes in spice samples
    (Pergamon-Elsevier Science Ltd, 2020) Ozak, Sezen Sivrikaya; Yilmaz, Yunus
    An environmentally friendly, simple method was carried out with the help of an ultrasonic assisted solid-liquid microextraction technique using a new deep eutectic solvent (DES) for the extraction and determination of Sudan dyes (I-IV) in spice samples. In this method, parameters affecting the optimization were researched and optimized such as DES composition, DES volume, ultrasonic time, temperature and, centrifuge time. The analytical performance of the developed method was quite satisfactory, the R-2 values were higher than 0.9989, and the limits of quantification were <1.17 mu g g(-1). Two different concentrations (10-50 mu g g(-1)) were spiked to Chili peppers, paprika, cumin and sumac spices for the applicability and accuracy of the developed microextraction method. Some of these spices were found to contain Sudan I and IV dyes. The recovery values for spiked samples were found to be between 85.55% and 99.29% and relative standard deviations were found to be <3.17% when using a 10 mu g g(-1) Sudan dyes concentration. The results showed that the developed method can be successfully applied for extraction and determination of Sudan dyes in spice samples. (C) 2020 Elsevier B.V. All rights reserved.