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Nio nanoflower based sorbent extraction for a novel HPLC–UV method for the determination of solifenacin in human plasma and its application to a prototype pharmacokinetic study
(Springer Nature Link, 2025) Ceylan, Burhan; Önal, Cem; Kurnaz Yetim, Nurdan; Hasanoğlu Özkan, Elvan; Önal, Armağan
Solifenacin is an active pharmaceutical product used in overactive therapy. The main goal of this work was to develop a high-performance liquid chromatographic (HPLC) method with ultraviolet detection for measuring the amount of quanti fied solifenacin in human plasma samples that is rapid, straightforward, and accurate. Prior to chromatographic analysis, a nanomaterial-based sorbent extraction technique utilizing NiO nanoflowers was employed for plasma sample preparation. In this method, NiO nanoflowers were employed, and the adsorption process underwent optimization. Chromatographic separation was carried out using a reversed-phase C18 analytical column (5 µm×4.6 mm×150 mm) with a mobile phase composed of water (0.2% triethylamine) and acetonitrile (30:70 v/v), and the pH was adjusted to 3.5 with ortho-phosphoric acid. The flow rate was set at 1.0 mL/min, and the investigation was performed using UV at 220 nm. The retention time of solifenacin is 3.10±0.01 min. The linear behaviour of the proposed approach was examined in the 0.01–30 ng/mL range (r 2=0.9995). The proposed method is in alignment with the criteria established by the European Medical Agency (EMA) about the accuracy, precision, repeatability, specificity, robustness and detection and quantification. Limit of detection and limit of quantification are determined to be 0.003 and 0.01 ng/mL, whereas relative standard deviation was determined to be less than 2.75% for intra-run and inter-run measurements. The plasma concentration–time profile and pharmacokinetic parameters such as AUC0–t , AUC0–∞, Cmax, tmax, and t1/2, were calculated according to the assays. The proposed method is feasible to investigate the bioequivalence, bioavailability, and routine analysis of the drug in plasma.
NiO-SnO2 nanocomposite as an adsorbent for the preconcentration of manganese ions in chamomile tea extract
(Elsevier, 2026) Şaylan, Meltem; Gürsoy, Selim; Zaman, Buse Tuğba; Bakırdere, Sezgin
Matricaria chamomilla L., referred to as chamomile, is a well-known medicinal plant that is widely distributed throughout the world. In this study, a novel NiO-SnO2 nanocomposite- assisted preconcentration method was established for efficient extraction and separation of manganese ions from chamomile tea extract. This pre concentration method was coupled with flame atomic absorption spectroscopy (FAAS). NiO-SnO2 nano composites were synthesized using simple one-pot co-precipitation procedure and calcined at 650 ◦C to obtain nanoparticles with sizes below 100 nm. X-ray diffraction (XRD) analysis indicated that the crystallite size of NiO SnO2 nanocomposites was estimated to be 46.03 nm using the Monshi–Scherrer equation. The LOD (limit of detection) and linear working range were determined as 3.6 μg/L and 10–100 μg/L, respectively. The proposed method was successfully validated, and recoveries ranged from 87.2 %–117.0 %. NiO-SnO2 nanocomposites represent a promising low-cost adsorbent for the preconcentration and subsequent determination of other heavy metal ions in diverse herbal extracts.
Computational insights into iron coordination disruption in the human transferrin–neisseria meningitidis bacterial protein complex
(MDPI Publishing, 2025) Dervişoğlu Özdemir, Celile; Duran, Gizem Nur; Fındık, Volkan; Özbil, Mehmet; Sağ Erdem, Safiye
Among many metal ions in biological systems, iron plays a fundamental role. Transferrins are iron-binding glycoproteins responsible for transporting Fe3+ in vertebrate blood. Neisse ria meningitidis, a Gram-negative pathogen causing meningitis, relies on iron for survival and acquires it from human transferrin (hTf) using two surface proteins, TbpA and TbpB. These proteins interact with hTf to form a ternary TbpA–TbpB–hTf complex, enabling iron capture from the host. The absence of an experimental crystal structure for this complex has hindered computational studies, a detailed understanding of Fe3+ dissociation, and designing efficient therapeutics. This study presents the first computational model of the ternary complex, its validation, and molecular dynamics simulations. Structural analyses revealed key electrostatic interactions regulating Fe3+ coordination and essential contact regions between proteins. The role of Lys359 from TbpA was investigated via QM/MM calculations by evaluating Fe3+ binding energies of isolated hTf, the ternary complex, and Lys359Ala, Lys359Arg, Lys359Asp mutant models. Results revealed that the proton trans fer from Lys359 leads to disruption of Tyr517–Fe3+ coordination, facilitating iron transfer to the bacterial system. Natural bond orbital analysis confirmed this mechanism. The findings provide new molecular insight into N. meningitidis iron acquisition and identify Lys359 as a potential target for covalent inhibitor design, guiding the development of novel therapeutics against meningococcal infection.
LC-MS/MS methods for the determination of paclitaxel in biological fluids: A review
(Gece Kitaplığı, 2025) Şenol, Mahmut Raşit; Sağlık Aslan, Serap
Oncology stands out as a dynamic field of science, driven by contin uous development and innovative research leading to advances in treat ment methods. In this context, paclitaxel is a chemotherapy drug that is effectively used in the treatment of a wide variety of cancer types. The drug’s areas of application include breast, ovarian, bladder, lung, prostate, melanoma, oesophageal cancers, Kaposi’s sarcoma, and various other solid tumours. This review details paclitaxel’s therapeutic indications, its mechanism of action at the cellular level, its role in suppressing tumour cell proliferation, as well as dosage adjustments, infusion protocols, routes of administration, and possible contraindications; it also emphasises the clinical importance of monitoring patients undergoing treatment. Pacli taxel, initially known as “taxol” when it was first discovered, is a natural diterpenoid compound derived from the Pacific yew tree (Taxus brevifo lia). The drug’s discovery was the result of natural product screening pro grammes conducted by the National Cancer Institute (NCI) in the United States in the late 1960s and early 1970s. During this process, research ers examined various plant extracts in an effort to identify compounds with anticancer potential, and paclitaxel’s pronounced cytotoxic effects attracted attention. In particular, its capacity to halt the cell cycle and induce apoptosis by inhibiting microtubule depolymerisation has made paclitaxel a priority agent in anticancer research (1).
Development and validation of an HPLC method for quantification of solifenacin in spiked human breast milk
(Korean Society of Analytical Sciences, 2025) Ceylan, Burhan; Çayci, Meltem; Önal, Cem; Önal, Armağan
An efficient and reliable reversed phase high performance liquid chromatography (HPLC) method was established and validated for the quantitative analysis of solifenacin succinate in fortified human breast milk samples. Chromatographic separation was carried out on a C18 column (150 × 4.6 mm, 5 μm particle size) and a isocratic mobile phase composed of acetonitrile and phosphate buffer (pH 3.5) in a 65:35 (v/v) ratio. The flow rate was at 1.1 mL/min, and detection was performed at 225 nm using a ultraviolet (UV) detector. The method exhibited excellent linearity in the range of 1.0 to 40.0 ng/mL (r² = 0.9999). The validation process was performed in accordance with European Medicines Agency (EMA) bioanalytical guidelines, and included selectivity, accuracy, precision, sensitivity, recovery, robustness, and stability assessments. The liquid-liquid extraction (LLE) procedure used for sample pretreatment provided satisfactory recovery (mean: 99.32 %) and minimized matrix interferences from breast milk. The method showed high reproducibility, did not require an internal standar, and offered a rapid analysis time of approximately 3.4 minutes. This study offers a simple, cost-effective, and sensitive HPLC-UV method for monitoring solifenacin levels in breast milk matrices, providing a valuable tool for evaluating drug safety during lactation.
Development of an HPLC method for the determination of fampridine (dalfampridine) in human plasma by fluorimetric derivatization and application to a prototype pharmacokinetic study
(Editions de l'Academie Republique Populaire, 2025) Ceylan, Burhan; Önal, Cem; Önal, Armağan
Fampridine (dalfampridine) is used to improve walking in people who have multiple sclerosis. In this study, a new, fast and sensitive HPLC method with fluorometric detection was developed for the determination of fampridine in human plasma and applied to a pharmacokinetic study. Fampridine was precolumn derivatized with 7-chloro-4-nitrobenzofurazan (NBD-Cl) and the fluorescent derivative was separated on a C18 (150 × 4.6 mm × 2.6 μm) analytical column at 30 ºC using a mobile phase composed of acetonitrile – 0.1% o-phosphoric acid in water (80:20, v/v) by isocratic elution with flow rate of 1.0 mL min–1 . The method was based on the measurement of the derivative using fluorescence detection (λex= 310 nm, λem = 365 nm). The retention time of fampridine is 4.10 ± 0.02 min. This currently developed method was validated according to EMA criteria by evaluating the specificity, linearity, precision, accuracy and robustness. The method was determined to be linear in a concentration range of 0.01–20 ng mL–1 with the correlation coefficient of 0.9996. LOD and LOQ were found to be 0.003 and 0.01 ng mL–1 , respectively. Intraday and interday RSD values were less than 2.45%. The plasma concentration-time profile and pharmacokinetic parameters such as AUC0–t, AUC0–∞, Cmax, tmax, t1/2, were calculated according to the assays. The presented method can certainly be used for bioequivalence and bioavailability investigations and routine analysis of the drug in plasma.
Fluorimetric derivatization-based HPLC-FL method for the prototype pharmacokinetic analysis of selexipag in human plasma
(Taras Shevchenko National University, 2025) Ceylan, Burhan; Çayci, Meltem; Önal, Cem; Önal, Armağan
A simple and cost-effective HPLC-FL method has been developed for measuring selexipag in human plasma, showcasing its suitability for pharmacokinetic research. Selexipag was precolumn derivatized with 7-chloro-4-nitrobenzofurazan (NBD-Cl) and the fluorescent derivative was separated on a C18 (150 mm × 4.6 mm × 2.6 μm) analytical column at 30 ºC using a mobile phase composed of acetonitrile – 0.1% o-phosphoric acid in water (70:30, v/v) by isocratic elution with flow rate of 1.0 mL min-1. The method was based on measuring the derivative using fluorescence detection (λex = 380 nm, λem = 420 nm). The retention time of selexipag is 6.40 ± 0.01 min. This currently developed method was validated according to EMA criteria by evaluating the specificity, linearity, precision, accuracy, and robustness. The method was determined to be linear in a concentration range of 0.01-20 ng mL-1 with a correlation coefficient of 0.9998. LOD and LOQ were found to be 0.003 and 0.01 ng mL-1, respectively. Intraday and interday RSD values were less than 1.75%. The plasma concentration-time profile and pharmacokinetic parameters such as AUC0–t, AUC0–∞, Cmax, tmax, t1/2, were calculated according to the assays. The presented method can be effectively used for bioequivalence and bioavailability investigations, as well as for routine analysis of the drug in plasma.
Development of a sensitive spectrophotometric method for determination of the charge-transfer complex of aripiprazole in pharmaceutical formulations: Spectrometric characteristics and analytical applications
(Taras Shevchenko National University, 2024) Dinçel, Demet; Bahadori, Fatemeh; Kepekçi Tekkeli, Şerife Evrim; Önal, Armağan
This study presents a simple, rapid, and accurate spectrophotometric method for the determination of Aripiprazole (ARP) in tablets. The determination procedure is based on the reaction of ARP with 7,7,8,8-tet racyanoquinodimethane (TCNQ), producing a colored product that was quantitated spectrophotometrically at 392 nm. Various variables affecting the reaction were optimized. The method exhibited a good linearity range with a correlation coefficient of 0.9994, observed as 0.25–3 μg/mL. The developed method was validated according to the International Council for Harmonisation (ICH) guidelines, assessing specificity, linearity, accuracy, precision, robustness, limit of detection (LOD), and limit of quantitation (LOQ). The formation of the CT-complex and the interaction sites were confirmed by elemental analysis, DSC, IR, and 1H NMR spectroscopy. The method was successfully applied to the determination of ARP in pharmaceutical preparation.
Quantification of agnuside in human plasma with a novel high-performance liquid chromatographic method and pharmacokinetic study
(Oxford University Press, 2025) Egeli, Derya; Tiris, Gizem; Kepekçi Tekkeli, Şerife Evrim
This study presents a combination of High Performance Liquid Chromatography (HPLC) and ultraviolet (UV) detection that provides the quantification of agnuside in human plasma specimens. Reverse-phase chromatographic separation was carried out with C18 column (150 mm × 4.6 mm × 5 μm), at 25°C with isocratic elution of the mobile phase containing methanol: 0.1% formic acid (35:65 v/v) at 0.6 mL/min flow rate. Experiments were carried out at a wavelength of 258 nm. The retention time of the analyte is 9.70 ± 0.01 min. The developed technique was validated based on the International Conference on Harmonization guideline. The correlation coefficient of the technique was 0.9915, and the calibration range was 5–125 μg/mL. The recovery value of the proposed method was found to be 101.4%, and the precision of the method was calculated as 6.35 with the highest RSD% value. A pharmacokinetic study was performed by administering agnuside to a healthy volunteer.
Preconcentration of bismuth using nickel hydroxide nanoflower from water samples and determination by FAAS
(Springer, 2025) Yıldız, Barış; Durukan, İlknur; Şaylan, Meltem; Zaman, Buse Tuğba; Bakırdere, Sezgin
In this study, a preconcentration strategy based on Ni(OH)2 nanofowers (NFs) was developed for the extraction/separation of bismuth ions from environmental water samples before the determination by fame atomic absorption spectrometry (FAAS). The homogeneous coprecipitation method was employed for the synthesis of the fower-shaped Ni(OH)2 and used as an adsorbent for the preconcentration of bismuth. The extraction variables were determined by a univariate optimization strategy to obtain maximum extraction performance. The optimal parameters of the method were as follows: 15 min mechanical shaking at 120 rpm, pH 6.0 bufer solution (1.0 mL), 20 mg of sorbent, and 250 µL of 6.0 M nitric acid for the elution. Under the optimized instrumental and extraction conditions, LOD (limit of detection), LOQ (limit of quantitation), and linear dynamic range were determined as 2.8 µg/L, 9.4 µg/L, and 0.010–0.30 mg/L, respectively. The enhancement factor of the sorbent-based method was calculated as 139.1-folds by comparing the slopes of calibration plots obtained from FAAS and the preconcentration method. To assess the feasibility and reliability of the developed method, tap water and spring water samples were analyzed under optimized conditions. The satisfactory %recoveries were obtained close to 100% using the direct comparison method. The obtained results show that the presented method is a promising candidate for efcient extraction and trace determination of bismuth in several sample mediums.
Magnetic micro solid-phase extraction for a novel UHPLC-DAD method for the determination of atomoxetine (ATX) in breast milk and human plasma
(Academia Română, 2024) Ceylan, Burhan; Kurnaz Yetim, Nurdan; Özcan, Cemile; Koç, Mümin Mehmet; Önal, Cem
Atomoxetine is a special pharmaceutics used for attention deficit hyperactivity disorder. It finds application in various age groups, including children, adolescents, and adults. Ultra high-performance liquid chromatographic technique (UHPLC) is an exceptional technique and provides swift, uncomplicated, and highly sensitive results. Such a technique has been formulated to analyse atomoxetine levels in both breast milk and human plasma. Magnetic micro solid phase extraction is simple, rapid, efficient, and precise method which was applied prior to chromatographic separation. In this method, magnetic adsorbents in the form of Fe3O4 magnetic nanoparticles were employed, and the adsorption process underwent optimization. Chromatographic separation was carried out using a reversed-phase C18 analytical column (5 μm × 4.6 mm × 150 mm) with a mobile phase composed of monobasic potassium dihydrogen orthophosphate (pH=6.8) and acetonitrile (50:50 v/v). The flow rate was set at 0.8 mL/min, and investigation was performed using DAD at 215±2 nm. The method's linearity was evaluated within the range of 0.5–20 μg/mL, achieving a correlation coefficient (r) of 0.999. Validation of the method encompassed accuracy, reproducibility, precision, robustness, specificity, quantification limits, and detection limits, adhering to EMA guidelines. The limit of detection (LOD) was found to be 0.03, while the limit of quantification (LOQ) was 0.11 μg/mL for both matrices. Interday and intraday relative standard deviation (RSD) values were determined to be below 2.5% for both assays. The suggested method is deemed to be a useful candidate for the conventional quantification of atomoxetine in human spiked breast milk and plasma.
Phenylsulfonylpiperazines as α-Glucosidase enzyme inhibitors: Design, synthesis, DFT calculations, docking and ADME studies
(Bitlis Eren Üniversitesi, 2024) Buran, Kerem; İnan, Yiğit; Akyüz, Gülşah Selin; Dervişoğlu Özdemir, Celile; Kocabaş, Fatih
Diabetes mellitus (DM) is one of the most common diseases affecting people all over the world. An important treatment for DM is the inhibition of the α-glucosidase enzyme. A wide range of biological activities of piperazine and sulfonamide moieties are known. In this study, five phenylsulfonyl piperazine derivatives were synthesized. Their inhibitory capacities were evaluated. The analogues (1-5) showed a good degree of inhibition of α-glucosidase enzyme. Compound 1 has the highest inhibition potential for the α-glucosidase enzyme. Its inhibition percentages (83.52±0.41) were higher than the reference molecule quercetin (81.41±0.02). In silico molecular docking studies were performed for the most potent compound 1 for α-glucosidase enzyme to determine possible protein-ligand interactions. Furthermore, a DFT study was carried out for the evaluation of the quantum mechanical and electronic properties. Finally, ADME profiles of the compounds were theoretically analyzed.
A simple UFLC method for determination of montelukast in human plasma
(ACG Publications, 2024) Önal, Cem; Kepekçi Tekkeli, Şerife Evrim; Önal, Armağan
In this investigation, an UFLC technique utilizing fluorimetric detection was reported for the analysis of Montelukast (MON) in plasma. The method involves pre-column derivatization using 4-bromomethyl-7- methoxycoumarin (BrMmC). The calibration curve linear concentrations from 10 to 1000 ng/mL. The method exhibited an average recovery rate of 95.49%. The newly developed method was effectively utilized to assess the pharmacokinetics of Montelukast (MON) following the administration of a single 10 mg tablet to a healthy male volunteer.
Spray-assisted drop formation liquid-phase microextraction for the determination of sertraline in environmental water samples with matrix-matching calibration in GC–MS
(SpringerOpen, 2024) Zeytinci, Nagehan Kübra; Akbıyık, Hilal; Tezgin, Emine; Zaman, Buse Tuğba; Dalgıç Bozyiğit, Gamze; Şaylan, Meltem; Bakırdere, Sezgin
Sertraline is used as an antidepressant drug for the treatment of psychiatric disorders, including anxiety and depres sion. In the current study, a simple and efective method was developed for the sensitive monitoring of sertraline in water samples using a GC–MS system. The spray-assisted droplet formation liquid-phase microextraction (SADF LPME) method was used as a sample preparation method for the enrichment of analytes. Accordingly, dichlo romethane was used as an extraction solvent and easily dispersed into a sample/standard solution using a lab-made modifed spray device without using a dispersing solvent. The signifcant factors afecting the SADF-LPME efciency, including sample pH, mixing conditions, extraction solvent type, and spray cycle, were univariately optimized to ascertain the extraction performance and applicability of the system. Under the optimized conditions, the plotted calibration curve of the method was linear in the range of 100.2–2011.7 µg/kg (mass-based standard preparation) with a good correlation coefcient (R2 ) of 0.9997. The detection and quantifcation limits of method were found to be 37.5 and 125 µg/kg, respectively. Validation of the method was successfully carried out using diferent tap water samples and applying a matrix-matching calibration strategy. The acceptable percent recoveries were recorded between 77.3 and 133.7%, with high repeatability. The recommended method is an alternative and fast extraction method with several advantages, including a simple experimental process, good dispersibility, and fast and superior extraction performance. It can be readily applicable to the monitoring and quantifcation of sertraline in tap water samples with good precision and accuracy.
Efficient removal of estrone and 17β‑estradiol from aqueous medium using UV irradiation‑assisted fenton process
(Springer Link, 2024) Dikmen, Yaren; Şaylan, Meltem; Oflu, Sude; Fırat Ayyıldız, Merve; Serbest, Hakan; Dalgıç Bozyiğit, Gamze; Bakırdere, Sezgin
The endocrine-disrupting compounds (EDCs) have high-risk implications for public health and the environment due to their potential to interfere with endocrine system functions. This study is based on an evaluation of the applying the UV-assisted Fenton process for the removal and degradation of 17β-estradiol and estrone in aqueous medium. The simple and affordable UV irradiation system was developed and applied to accelerate the Fenton reaction. High performance liquid chromatography (HPLC) was employed for the quantitative measurements of estrogenic hormones at 230 nm, which is highly sensitive and capable of accurately measuring hormones within 15 min. The LOD/LOQ values of HPLC system were recorded to be 0.03/0.11 mg/kg and 0.05 /0.15 mg/kg for estrone and 17β-estradiol, respectively. Fe3O4 magnetic nanoparticles and iron (II) sulfate solution were evaluated as appropriate iron sources under fixed UV irradiation to assess the Fenton process. The main parameters, namely hydrogen peroxide (H2O2) amount, iron (II) sulfate amount, pH, and UV irradiation period, were optimized univariately for determining the optimum conditions. The optimum conditions were recorded to be: 0.70 mL of pH 3.0 buffer solution, 1.25 mL of H2O2, 0.80 mL of 100 mg/L Fe2+ solution, and an irradiation time of 60 min. The removal experiments were also carried out on domestic wastewater to validate the system’s applicability. The percent removal efficiencies of both estrogenic hormones were calculated at higher than 99%. These results showed that high efficiency was achieved within the detection limits of the HPLC system. This proves the possibility of complete degradation of the analytes and their efficiency and practicality for pollution control and water quality improvement in future studies.
Development of an HPLC-UV method for the simultaneous determination of allantoin and D-panthenol in cosmetic products containing Aloe vera extracts
(Akadémiai Kiadó (AK), 2024) Ceylan, Burhan; Kepekçi Tekkeli, Şerife Evrim
A simple, fast and selective analytical method has been developed for the simultaneous determination of allantoin and D-panthenol in cosmetic products containing Aloe vera extracts. The proposed method depends on reversed-phase liquid chromatography with isocratic flow profile of the mobile phase composed of acetonitrile–10 mM phosphoric acid (pH 2.5) (85:15, v/v), with a C18 column at 30 8C. The analytes were detected with UV–vis. detector at 210 nm. The injection volume was 20 μL. The linearity ranges were found to be 0.2–20 and 0.1–10 μg mL 1 for allantoin and D-panthenol, respec tively. LOD values were found to be 0.07 μg mL 1 and 0.03 μg mL 1 , LOQ values were found to be 0.2 and 0.1 μg mL 1 for allantoin and D-panthenol, respectively. No interference was observed from concomitants. The developed method was applied to the analysis of 10 different type cosmetic products. It is foreseen that the method will be able to be used in order to carry out routine analysis, quality control and standardization in cosmetic products containing allantoin and D-panthenol.
CoSn(OH)6 nanocubes as a solid sorbent for the effective preconcentration of copper ions in cinnamon (Cinnamomum zeylanicum) extract
(Elsevier, 2024) Bahçıvan, Aleyna; Şaylan, Meltem; Sağdıç, Osman; Bakırdere, Sezgin
This study was aimed at developing a simple and efficient CoSn(OH)6 nanocubes-based preconcentration method for the preconcentration of copper ions from cinnamon extracts for determination by flame atomic absorption spectrometry. The cube-shaped sorbent was synthesized using the simple stoichiometric co-precipitation method under ambient conditions. Experimental factors of the method were evaluated with a comprehensive optimization approach to maximize the extraction efficiency for the analyte. Under the optimal conditions, the limit of detection (LOD), limit of quantitation (LOQ), and linear dynamic range were recorded as 0.98 µg/L, 3.28 µg/L, and 4.0-75 µg/L, respectively. The enhancement factor was calculated as 101.6-fold by comparing the LODs of the optimized and direct analysis systems. Percent recoveries were found to be within an acceptable range (77.6-115 %), with high repeatability using matrix matching calibration strategy. Results validated the proposed method as a highly efficient extraction approach for the monitoring of copper ions in herbal cinnamon extracts.
Synthesis of nanocube-shaped cobalt tin hydroxides for the preconcentration of lead in environmental seawater collected from antarctic region
(Wiley-VCH GmbH, 2024) Şaylan, Meltem; Fırat Ayyıldız, Merve; Zaman, Buse Tuğba; Polat Korkunç, Ümmügülsüm; Gürsoy, Selim; Çetin, Gülten; Bakırdere, Sezgin
Here, a simple/efficient analytical strategy based on dispersive solid phase extraction was developed using CoSn(OH)6 nanocubes for lead ions from environmental water samples by FAAS (flame atomic absorption spectrometry). CoSn(OH)6 was synthesized as an adsorbent using the co-precipitation method and characterized. The characterization studies proved the cube-shaped morphology and uniform size distribution. The optimal experimental conditions were found by optimization studies and, the limit of quantification (LOQ), limit of detection (LOD), linear dynamic range were recorded as 37.6 μg/L, 11.3 μg/L, and 40–600 μg/L, respectively. The enhancement factor of the presented method was calculated as 158.7-folds compared to the LOD of the conventional FAAS system. Recovery experiments were performed to check the method's applicability/accuracy and the percent recovery results varied from 89.0 % to 112.9 %. According to these findings, the developed method was successfully applied for the quantitative determination of the target analyte in a seawater sample matrix.
Pharmacokinetic analysis of febuxostat in human serum by UFLC based on fluorimetric derivatization
(Editions de l'Academie Republique Populaire, 2024) Binay, Emrullah; Önal, Cem; Önal, Armağan; Kepekçi Tekkeli, Şerife Evrim
An ultra fast liquid chromatographic (UFLC) method using fluorimetric detection for the quantitation of Febuxostat (FEB) in human serum was developed by precolumn derivatization with 4- bromomethyl-7-methoxy coumarin (BrMmC). The derivatization was catalyzed with dibenzo-18-crown-6-ether to produce a fluorescent derivative which was determined through fluorescence measurement with excitation at 320 nm and emission at 395 nm wavelengths. A C18 column with 100 cm  4.6 mm, 3 µm particule size was used for the UFLC separation procedure. A mixture of acetonitrile: methanol: 0.05 M aqueous ammonium acetate (pH 5.0) (40:40:20, v/v/v) was used as mobile phase. During the procedure, the flow rate was maintained at 0.5 mL/min. A calibration curve was then plotted as 0.005–3.0 µg/mL with a detection limit of 0.0022 µg/mL and quantification limit of 0.0073 µg/mL. The mean recovery to reveal the accuracy and relative standard deviation (RSD) that indicates the precision of the method were found out to be 85.20 % and less than 3.52 %, respectively. The utility of the new method has been demonstrated by measuring the pharmacokinetics of FEB by administration of 80 mg tablets to a healthy female volunteer, aged 42.
Implementation of simple and effective fine droplet formation-based spray-assisted liquid phase microextraction for the simultaneous determination of twenty-nine endocrine disruptor compounds and pesticides in rock, soil, water, moss, and feces samples from antarctica using gas chromatography-mass spectrometry
(Springer, 2024) Zaman, Buse Tuğba; Dalgıç Bozyiğit, Gamze; Şaylan, Meltem; Koçoğlu, Elif Seda; Kartoğlu, Bedrihan; Aydın, Efe Sinan; Girgin, Ayça; Borahan, Tülay; Oflu, Sude; Kılınç, Yağmur; Bakırdere, Emine Gülhan; Bakırdere, Sezgin
This study established the simultaneous determination of the selected endocrine-disrupting compounds (EDCs) and pesticides in rock, soil, water, moss, and feces samples collected from the Antarctic region. The spray-assisted droplet formation-based liquid phase microextraction (SADF-LPME) coupled to GC–MS system was developed and validated for the screening and monitoring of 29 selected EDCs and pesticides. Binary solvent system, 1:1 (v/v) dichlormethane: 1,2-dichloroethane mixture was employed as an extraction solvent and sprayed onto sample or standard solutions using a straightforward and practical spray apparatus. The factors afecting the extraction process such as extraction solvent type and ratio, extraction solvent volume (spray repetition), vortexing period, and sample pH were properly optimized. Analytical fgures of the merit of the method were recorded under the optimal extraction/chromatographic conditions. The LOD, LOQ, and enhancement factor were in the range of 1.0 to 6.6 ng/g, 3.2 to 22.1 ng/g, and 3.7 to 158.9, respectively. The method demonstrated a good linear working range for all the selected analytes with proper coefcients of determination. The usability and reliability of the microextraction strategy was confrmed using seawater, moss, and soil samples, and the %recoveries were within an acceptable range (>70%) for all examined samples. The environmental samples collected from the Horseshoe and Faure Islands of the Antarctica region were analyzed to assess the potential pollution of EDCs and pesticides. This method has the potential to be employed for the analysis of EDCs in routine analytical laboratories and for controlling and screening the organic pollutant content of diferent environmental samples.

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