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Yayın Analysis of capsaicinoids in chilli sauce with ultra fast liquid chromatography(Bezmialem Vakıf Üniversitesi, 2022) Ceylan, Burhan; Önal, Cem; Önal, ArmağanObjective: In current study, quantification of the capsaicinoids in chilli sauces based on a sensitive ultra fast liquid chromatography method and derivatization with dansyl chloride (DNS-Cl) was described. Capsaicinoids are biosynthesized as secondary metabolites by chilli sauces. The major components of capsaicinoids are capsaicin (CPS) and dihydrocapsaicin (DCPS). Methods: Phenol groups within the CPS and DCPS are suitable for derivatization reaction using DNS-Cl (chemically named as 5-(dimethylamino) naphthalene-1-sulfonyl chloride) at pH 10 with 0.5 M sodium bicarbonate which leads formation of a derivative highly fluorescent properties that can be measured at 520 nm following excitation at 360 nm wavelength. Separation of the compounds was conducted on a chromatographic system having a mobile phase formed by a combination of acetic acid (0.5 M, pH 7.0 with NaOH) solution and acetonitrile under solvent programming on a consistent flow rate of 0.4 mL. min-1 using a C18 column. Results: Method validation was evaluated as per the regulations described in International Conference on Harmonization Guidelines. The calibration graph for CPS and DCPS was linear between 0.2 and 200 µg mL-1. Conclusion: The proposed analytical procedure represents a simple, time and cost effective method with a suitable selectivity regarding quantification of capsaicinoids in chilli sauces.Yayın Determination of apigenin in cosmetics containing chamomile by high-performance liquid chromatography with ultraviolet detection (HPLC-UV)(Taylor & Francis, 2023) Serim, Ecem; Ceylan, Burhan; Kepekçi Tekkeli, Şerife EvrimA simple, rapid, and precise high performance liquid chromatography (HPLC) method was developed to determine the flavonoid apigenin in cosmetic products containing chamomile extracts. A C18 column was used as stationary phase and 70:30 ethanol:water was used as mobile phase with a 1 mL/min flow rate and isocratic elution. The temperature was stabilized at 25 degrees C during the separation. The injection volume was 50 mu L. The apigenin peak was eluted at 4.15 +/- 0.4 min. The method was validated according to International Conference on Harmonisation (ICH) criteria in terms of linearity, limit of detection, limit of quantitation, selectivity, sensitivity, robustness, accuracy, and precision. The limits of detection and quantitation were 0.060 and 0.2 mu g/mL respectively. The linear range was from 0.2 to 20 mu g/mL. The relative standard deviation values for intraday and interday analyses were less than 1.64%. The developed procedure was applied to the analysis of various cosmetic products. It is expected that the method is suitable for routine analysis, quality control and standardization of cosmetic products for apigenin.Yayın Determination of carnosic acid by a novel HPLC-UV method in human plasma and application to a prototype pharmacokinetic study(Oxford Academic, 2024) Ceylan, Burhan; Tırıs, Gizem; Kepekçi Tekkeli, Şerife EvrimAn HPLC method with UV detection was developed for the determination of carnosic acid in human plasma and applied to a pharmacokinetic study after oral administration of Rosemary extract to a healthy volunteer. Sample preparation depends on liquid-liquid extraction with hexane. Chromatographic separation was achieved with C18 column (150 mm × 4.6 mm × 5 μm), at 25°C with isocratic elution, mobile phase composed of solution A (methanol), and solution B (2% o-phosphoric acid in water) (90:10, v/v) at flow rate of 1.0 mL/min. The analyte was detected at 230 nm. The retention time is 4.20 ± 0.03 min. The method was validated in terms of accuracy, precision, specificity, robustness and detection and quantification limits, in accordance with European Medicines Agency guidelines. LOD and LOQ were found to be 0.075 and 0.25 ng/mL, respectively. The method was applied to the analysis of carnosic acid in human plasma with good recovery as 91.7%. The plasma concentration-time profile and pharmacokinetic parameters: AUC0-t, AUC0-∞, Cmax, tmax, t1/2 were calculated according to the assays. The method can certainly be used for routine analysis of carnosic acid in human plasma after oral administration of Rosemary extract, and for phase I clinical studies and bioavailability-bioequivalance studies as well.Yayın Development of an HPLC method for the determination of mesalazine in human plasma by fluorimetric derivatization and application to a prototype pharmacokinetic study(Springer, 2022) Ceylan, Burhan; Kepekçi Tekkeli, Evrim; Önal, CemIn this study, a new, fast and sensitive HPLC method with fluorometric detection was developed for the determination of mesalazine in human plasma and applied to a pharmacokinetic study. Mesalazine was precolumn derivatized with NBD-Cl and the fluorescent derivative was separated on a C18 (150 x 4.6 mm x 2.6 mu m) 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 the measurement of the derivative using fluorescence detection (lambda(ex) = 280 nm, lambda(em) = 325 nm). The retention time of mesalazine is 3.08 +/- 0.06 min. Nortriptiline was used as internal standard. This currently developed method was validated according to ICH criteria by evaluating the specificity, linearity, precision, accuracy and robustness. The method was determined to be linear in a concentration range of 0.25-1.5 mu g mL(-1) with the correlation coefficient of 0.9997. LOD and LOQ were found to be 0.075 and 0.25 mu g mL(-1), respectively. Intraday and interday RSD values were less than 5.92%. The plasma concentration-time profile and pharmacokinetic parameters such as AUC(0-t), AUC(0-infinity), C-max, t(max), t(1/2), 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.Yayın 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 EvrimA 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.Yayın 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, CemAtomoxetine 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.Yayın A novel HPLC method for selexipag in human plasma and application to a prototype pharmacokinetic study(Akademiai Kiado, 2023) Ceylan, Burhan; Tırıs, Gizem; Kepekçi Tekkeli, Şerife Evrim; Önal, Cem; Önal, ArmağanA novel simple and cost effective HPLC technique was presented for the quantification of selexipag (SLP) in human plasma sample and the technique’s applicability to a pharmacokinetic investigation. Chromatographic separation was achieved with C18 (5 μm 3 4.6 mm 3 150 mm) column, at 30 8C with isocratic elution, mobile phase composed of solution A (acetonitrile), and solution B (0.5% formic acid) (65:35 v/v) at flow rate 1.2 mL min 1 . The linearity range is 10–150 ng mL 1 . As sample preparation step human plasma was precipitated with acetonitrile and the detection was provided at 300 nm. The retention time is 8.20 ± 0.02 min. LOD is found to be 3.3 ng mL 1 for drug. The method was applied to the analysis of SLP in human plasma with good recovery as 97.83%. Validation of the studied methods was carried out according to EMA guideline. The new method applied on a prototype pharmacokinetic study by administration of 800 μg SLP to a healthy volunteer and parameters like AUC0–24, AUC0–∞, Cmax, tmax, and t1/2 were assessed.Yayın An UPLC method for the determination of sorafenib in human plasma by fluorimetric detection with pre-column derivatization and application to a pharmacokinetic study(Editura Academiei Romane, 2022) Tırıs, Gizem; Kepekçi Tekkeli, Şerife Evrim; Önal, Cem; Ceylan, Burhan; Önal, ArmağanThis research presents a new, sensitive and selective UPLC method with fluorometric detection for the determination of sorafenib in human plasma and application of the method to a pharmacokinetic study. Sorafenib was precolumn derivatized with 7-chloro-4-nitrobenzofurazan (NBD-Cl) and the separation of the fluorescent derivative was performed with a C18 column (50 mm x 2.1 mm, 1.7 µm) at 40ºC using a mobile phase composed of acetonitrile - 0.1% trifluoroacetic acid in water (60:40, v/v) by isocratic elution with flow rate of 0.5 mL min−1 . The injection volume was 7 µL. The method depends on the measurement of the derivative using fluorescence detection (λex = 398 nm, λem = 425 nm). The retention time of sorafenib was 3.10 ± 0.02 min. The novel method was validated in accordance with ICH criteria by studying on the parameters such as specificity, linearity, precision, accuracy and robustness. The method was determined to be linear in a concentration range of 0.25-10 µg mL−1 with the correlation coefficient of 0.9995. Limit of detection and quantitation were found to be 0.075 and 0.25 µg mL−1 , respectively. Intraday and interday RSD values were less than 5.48%. The plasma concentration–time profile and pharmacokinetic parameters such as AUC0–t , AUC0–∞, Cmax, tmax, t1/2 were measured according to the assays. The proposed method is feasible to investigate the bioequivalence and bioavailability and routine analysis of the drug in plasma.
