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    Determination of 1-Deoxynojirimycin by a developed and validated HPLC-FLD method and assessment of In-vitro antioxidant, alpha-Amylase and alpha-Glucosidase inhibitory activity in mulberry varieties from Turkey
    (ELSEVIER GMBH, 2019) Eruygur, Nuraniye; Dural, Emrah
    Background: Morus alba and Morus nigra leaves which have been widely used as herbal teas in Anatolian region of Turkey, were extracted twice by 50 mM HCI solution, derivatized with 9-fluorenylmethyl chloroformate and analyzed by reversed phase HPLC equipped with a fluorescence detector. Hypothesis/Purpose: This study was performed to determine the main antidiabetic active compounds 1-deoxynojirimycin by HPLC method and evaluate the in-vitro antioxidant and antidiabetic activity of ethanol extracts prepared from Morus alba L. and Morus nigra leaves. Study Design: A reliable simple, and rapid high-performance liquid chromatographic (HPLC) method for the determination of 1-deoxynojirimycin in M. alba L. and M. nigra leaves with fluorimetric detection after pre-column derivatization with 9-fluorenylmethyl chloroformate was developed. In addition, the chemical composition of ethanol extract of mulberry leaves was analyzed with GC-MS. Methods: Separation and quantitation were performed on C18, 250 x 4.6 mm, 5 mu m analytical column. Mobile phase consisted of acetonitrile and 0.1% acetic acid solution (1:1, v/v) was performed applied to the column 1.0 ml/min flow rate at 26 degrees C. Potential antioxidant activity of ethanol extract of different mulberry varieties were evaluated by DPPH, and ABTS radical scavenging assay as well as total phenol and flavonoid content were determined. In addition, alpha-amylase and alpha-glucosidase activity was determined by 96-well plate method to evaluate the probable antidiabetic potential use of Turkish mulberry leaves. Results: The isocratic HPLC method showed excellent correlation coefficient (r(2) = 0.9985) between 0.3 and 30 mu g/ml calibration points. The method was specific and sensitive with detection and quantification limits of 1.07 and 3.27 ng/ml, respectively. Intraday and interday method precision (n = 5) were < 7.3 (RSD%). Intraday and interday method accuracy (n = 5) were between 3.77 and (-8.35) (RE%). The average method recovery (n = 3) was 102.5%. The results showed that the content of 1-deoxynojirimycin in leaves of Morus alba L. was 0.103% (n = 3), and in leaves of M. nigra L. was 0.102%. 2-hexadecen-1-ol, oleamide, 2-propenoic acid, and cyclododecane were identified as the major compounds by GC-MS in the ethanol extract of mulberry leaves. Conclusion: The obtained robustness values from emission and excitation detection, mobile phase ingredients and flow rates changes showed that method was very strong. This work contributes to the knowledge of antioxidant and antidiabetic properties of Morus species, thus may be provide useful data in evaluation of food products and pharmaceutical preparations produced from Morus species.
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    Determination of benzene, toluene, ethylbenzene, p-, m-, o-xylene, and n-butyl acetate in urine by a validated gas chromatography method: Application to an occupational monitoring study
    (Univ Sao Paulo, Conjunto Quimicas, 2025) Dural, Emrah; Kaya, Betul Isiner; Mergen, Gorkem; Boran, Erhan; Soylemezoglu, Tulin
    This study was aimed to determine occupational and non-occupational exposure to benzene, toluene p-m-o-xylene (BTEXs) and butyl-acetate (nBA). The aim of this work was to develop a simple, sensitive, and reliable chromatographic method using urine, a non-invasive human sample. The method was applied to samples collected from furniture spray workers (n=53) who are at risk of exposure to BTEXs and nBA and office workers (n=51) who have no known exposure risk. Method validation tests, include the sensitivity (LOD <= 0.018 ng/mL), precision (RSD <= 4.1), accuracy (RE% (-3.9)-4.7), recovery (96.1-103.8%) and linearity (r(2)>= 0.999). Urinary benzene (1.77 vs 1.23 ng/mL, exposed-control, respectively), toluene (51.22 vs 0.77 ng/mt), ethylbenzene (9.25 vs 6.69 ng/mt), para-xylene (1.73 vs 0.62 ng/mt), meta-xylene (2.58 vs 1.20 ng/mt), ortho-xylene (1.61 vs 0.88 ng/ mL), and butyl acetate (33.14 vs 1.63 ng/mL) concentrations were determined in the exposed and control group samples. Significant correlations were found between benzene (p=0.286*), ethylbenzene (p=0.552***) and o-xylene (p=0.292*) levels and smoking status in samples belonging to the control group. The occupationally-exposure-risk group samples have significantly higher BTEXs and nBA concentrations than the control (p<0.001). It was determined that smoking was a significantly effective factor in exposure to benzene, ethylbenzene and o-xylene in the control group.
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    Determination of diazepam in human plasma by developed and validated a high-performance liquid chromatographic ultraviolet method
    (Istanbul Univ, Fac Pharmacy, 2022) Dural, Emrah; Kaya, Beyza Nur
    Background and Aims: Diazepam is accepted as a safer drug to medicate in many serious cases, acting as an anticonvulsant, an anxiolytic and a treatment for many types of poisoning. Monitoring it is important in achieving successful treatment and reducing the risk of toxic effects. In this study, it is aimed to develop and validate a sensitive, repeatable, and reliable method based on high-performance liquid chromatographic analysis for the determination in human plasma. Methods: Separation was carried out using a reverse-phase C18 column (4.0 mm x 150 mm, 3 mu m) at 30 degrees C. The solution was prepared with a 10 mM phosphate buffer and acetonitrile (1:1, v/v) was employed as a mobile phase at the isocratic flow with 0.5 mL/min rate. Quantification was applied at 230 nm. A solid-phase extraction method was established and optimized, which was then used in the preparation of the plasma (0.5 mL) samples to the analysis. Results: The method was found to be linear (r(2) = 0.9805) between 100 and 1200 ng/mL. The analysis run was <= 12 min. Intraday and inter-day accuracy were found between -5.78 and 5.93 and precision was <= 1.82%. The limit of detection and quantification were calculated as 20.42 and 61.86 ng/mL, respectively. Recovery was found between the range of 95.12% and 106.83%. The method was determined to be robust according to changes in UV, mobile phase organic solvent content, mobile phase pH, column temperature, and operator. Conclusion: This simple, sensitive and reliable method is suggested for accredited-reference laboratories working on the therapeutic drug monitorization and/or overdose-toxicological quantified analysis of diazepam in human plasma.
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    Determination of diazepam in human plasma by developed and validated a high-performance liquid chromatographic ultraviolet method
    (İstanbul Üniversitesi, 2022) Dural, Emrah; Kaya, Beyza Nur
    Background and Aims: Diazepam is accepted as a safer drug to medicate in many serious cases, acting as an anticonvulsant, an anxiolytic and a treatment for many types of poisoning. Monitoring it is important in achieving successful treatment and reducing the risk of toxic effects. In this study, it is aimed to develop and validate a sensitive, repeatable, and reliable method based on high-performance liquid chromatographic analysis for the determination in human plasma.Methods: Separation was carried out using a reverse-phase C18 column (4.0 mm x 150 mm, 3 μm) at 30 °C. The solution was prepared with a 10 mM phosphate buffer and acetonitrile (1:1, v/v) was employed as a mobile phase at the isocratic flow with 0.5 mL/min rate. Quantification was applied at 230 nm. A solid-phase extraction method was established and optimized, which was then used in the preparation of the plasma (0.5 mL) samples to the analysis.Results: The method was found to be linear (r2= 0.9805) between 100 and 1200 ng/mL. The analysis run was ≤12 min. Intra- day and inter-day accuracy were found between -5.78 and 5.93 and precision was ≤1.82%. The limit of detection and quan- tification were calculated as 20.42 and 61.86 ng/mL, respectively. Recovery was found between the range of 95.12% and 106.83%. The method was determined to be robust according to changes in UV, mobile phase organic solvent content, mobile phase pH, column temperature, and operator.Conclusion: This simple, sensitive and reliable method is suggested for accredited-reference laboratories working on the therapeutic drug monitorization and/or overdose-toxicological quantified analysis of diazepam in human plasma.
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    Determination of Mirtazapine and Desmethyl Mirtazapine in Human Plasma by a New Validated HPLC Ultraviolet Method with a Simple and Reliable Extraction Method: Application to Therapeutic Drug Monitoring Study by 62 Real Patient Plasma
    (Shaheed Beheshti Univ, Sch Pharmacy, 2020) Dural, Emrah; Baskak, Nilay Sedes; Ozcan, Hatice; Kir, Yagmur; Baskak, Bora; Suzen, Halil Sinan
    Determination of mirtazapine (MRP) during psychopharmacotherapy in biological fluids is essential to achieve successful therapy, to avoid toxicity related to drug interactions, genetic variability, and poor compliance. A new, rapid, and sensitive high-performance liquid chromatography method has been developed in human plasma for the determination of MRP and N-desmethylmirtazapine (NDM) that is an active metabolite. The separation was achieved on a reverse-phase C18 250 x 4.6 mm i.d., ODS-3 column using programmed gradient elution at 40 degrees C. 20 mM potassium phosphate buffer (pH 3.9), acetonitrile, and triethylamine (75.0:24.9:0.1, v/v/v) were used as mobile phase A. Mobile phase B consisted of absolute acetonitrile. Clozapine was used as an internal standard The method showed linearity with good determination coefficients (r(2)>= 0.9981) for each analyte. Intra-day and interday assay precisions (RSD%) were found less than 3.4 and 2.9 for MRP and NDM, respectively. The intraday and interday accuracy (RE%) of the method were calculated between (-2.8) and 5.5. A new extraction method was used in the study and an excellent recovery (average) values for MRP and NDM (94.4%, 106.6%, respectively) was obtained. The method was specific and sensitive as the limit of detection (LOD) were 0.17 for MRP and 0.15 ng/mL for NDM. This method was applied properly to plasma samples taken from patients receiving MRI (n = 62) treated with 15-30 mg / day. The obtained and statistically evaluated plasma MRP and NDM levels which were 28.6 +/- 13.8 and 12.3 +/- 6.5 (mean +/- SD). The described procedure is relatively simple, precise, and applicable for routine therapeutic drug monitoring especially in psychiatry clinics and toxicology reference laboratories.
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    Determination of patulin levels in apple juices by HPLC-UV
    (ELSEVIER IRELAND LTD, 2017) Dural, Emrah
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    Determination of phenytoin in human plasma by a validated hplc method: Application to therapeutic drug monitoring study running title: Measurement of phenytoin in plasma by a novel hplc method
    (İstanbul Medipol University, 2021) Dural, Emrah; Bolayır, Aslı; Çiğdem, Burhanettin
    The aim of this study was to develop a simple and reliable HPLC method for the determination of phenytoin (PHT) in human plasma. Accuracy (RE%) were determined between (-0.93%) to 2.49% and precision (RSD%) values was ?7.94. The quantitation limit was 3.54 µg/mL and recovery was found between 82.15% and 101.06%. The method was applied to real plasma samples (n = 7). Plasma-PHT levels were found between 1.12 and 18.76 µg/mL (9.52 ± 7.78, mean±SD). Both the plasma and dose-rated plasma results of PHT showed so high RSD% which were between 81.74% and 89.61%. In addition plasma-PHT levels were outside the recom-mended treatment range in 4 of the 7 patients (57.14%) examined, and also surpris-ingly PHT could not be detected in a patient’s plasma. This procedure is relatively simple, precise, and applicable for routine therapeutic drug monitorization of PHT in neurology clinics or toxicological analyses in reference laboratories. © 2021, İstanbul Medipol University. All rights reserved.
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    Determination of Selected Phthalates in Some Commercial Cosmetic Products by HPLC-UV
    (Bentham Science Publ Ltd, 2020) Dural, Emrah
    Aim and Scope: Due to the serious toxicological risks and their widespread use, quantitative determination of phthalates in cosmetic products have importance for public health. The aim of this study was to develop a validated simple, rapid and reliable high-performance liquid chromatography (HPLC) method for the determination of phthalates which are; dimethyl phthalate (DMP), diethyl phthalate (DEP), benzyl butyl phthalate (BBP), di-n-butyl phthalate (DBP), di(2-ethylhexyl) phthalate (DEHP), in cosmetic products and to investigate these phthalate (PHT) levels in 48 cosmetic products marketing in Sivas, Turkey. Materials and Methods: Separation was achieved by a reverse-phase ACE-5 C-18 column (4.6 x 250 mm, 5.0 mu m). As the mobile phase, 5 mM KH2PO4 and acetonitrile were used gradiently at 1.5 ml min(-1). All PHT esters were detected at 230 nm and the run time was taking 21 minutes. Results: This method showed the high sensitivity value the limit of quantification (LOQ) values for which are below 0.64 mu g mL(-1) of all phthalates. Method linearity was >= 0.999 (r(2)). Accuracy and precision values of all phthalates were calculated between (-6.5) and 6.6 (RE%) and <= 6.2 (RSD%), respectively. Average recovery was between 94.8% and 99.6%. Forty-eight samples used for both babies and adults were successfully analyzed by the developed method. Results have shown that, DMP (340.7 mu g mL(-1) +/- 323.7), DEP (1852.1 mu g mL(-1) +/- 2192.0), and DBP (691.3 mu g mL(-1) +/- 1378.5) were used highly in nail polish, fragrance and cream products, respectively. Conclusion: Phthalate esters, which are mostly detected in the content of fragrance, cream and nail polish products and our research in general, are DEP (1852.1 mu g mL(-1) +/- 2192.0), DBP (691.3 mu g mL(-1) +/- 1378.5) and DMP (340.7 mu g mL(-1) +/- 323.7), respectively. Phthalates were found in the content of all 48 cosmetic products examined, and the most detected phthalates in general average were DEP (581.7 mu g mL(-1) +/- 1405.2) with a rate of 79.2%. The unexpectedly high phthalate content in the examined cosmetic products revealed a great risk of these products on human health. The developed method is a simple, sensitive, reliable and economical alternative for the determination of phthalates in the content of cosmetic products, it can be used to identify phthalate esters in different products after some modifications.
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    Determination of seven synthetic colourants in pharmaceutics, foods, and beverages by a validated HPLC-PDA method: A risk assessment study
    (Academic Press Inc., 2024) Tamer, Fatma Selen; Oymak, Tülay; Dural, Emrah
    A simple, rapid, sensitive and reliable high-performance liquid chromatography method based-on ultraviolet determination was developed and validated for the simultaneous determination of the tartrazine-TR, sunset yellow-SY, ponceau-4R P4R, allura red-AR, patent blue-PBV, brilliant blue-BB, erythrosine B-EB. The limit of detections were found as ?0.083 µg/mL, determination coefficiencies were found as ?0.999 in the range of 0.5 – 20 µg/mL for all colourants. Precision was ?6.75 (RSD) and accuracy was between (-6.52) and 6.80 (RE%). This developed analytical method was successfully used to quantitatively detect the presence of these synthetic colourants in confectionery (n = 13), beverages (n = 12) and pharmaceutical products (n = 13) and a risk assessment was made based on the lowest exposure scenario. The risk index values determined in confectionery range between 0.10 and 5.78 (1.46 ± 1.52, mean ± SD), in beverages range between 0.001 and 2.79 (0.034 ± 0.082The risk index of five of the monitored confectionery samples (38.50 %) was determined to be above one in terms of the relevant food dyes. © 2024 Elsevier Inc.
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    Determination of synthetic colorants in cosmetic products by reversed-phase high-performance liquid chromatography coupled with diode-array detector
    (Marmara Univ, 2019) Filiz, Zeynep; Oymak, Tulay; Dural, Emrah
    This study aimed at developing and validating a reversed-phase (RP) high-performance liquid chromatography (HPLC) method, for simultaneous determination of five synthetic dyes called tartrazine (TRZ), sunset yellow (SY), allura red AC (AR), brilliant blue FCF (BB) and erythrosine B (EB) in cosmetic samples. The separation was performed by a C18 reverse phase analytical column (4.6 x 250 mm, 5 mu m) at 30 degrees C with gradient elution and the mobile phase contained 20 mM ammonium acetate buffer, acetonitrile and methanol. Flow was 1.0 mL/min. Detection wavelengths of diode array detector (DAD) were set at 420, 480, 510, 634 and 530 nm for TRZ, SY, AR, BB and EB, respectively. The dyes were analysed in 24 min. The limits of detection (LOD) was <= 0.18 mu g/mL. The recovery was between 88.7 and 103.0%. Precision was <=. 7.33 (RSD%) and accuracy was 3.0 (RE%). It was determined that 7 different cosmetic samples analyzed, consisting of soap, shower gel, eyeshadow, mouthwash, and lip pencil contained synthetic dyes at a concentration of 0.29 to 10.81 mg/ g.
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    Determination of Urinary Total Hydroxyproline by HPLC with UV and EC Detectors
    (CHEM SOC PAKISTAN, 2018) Kaya, Betul Isiner; Dural, Emrah; Kenduzler, Erdal; Soylemezoglu, Tulin
    Hydroxyproline is found in high concentrations in connective tissue proteins. It is remarkably useful to detect it because variation in urine levels of hydroxyproline is associated with various diseases. High performance liquid chromatography methods, in which ultraviolet and electrochemical detectors were used, were developed and validated for the determination of hydroxyproline in urine. Both methods included acid hydrolysis and derivation. The most appropriate time, temperature and pH were identified to optimize derivatization processes. Limits of detection were calculated as 1.57 mu g/mL, 0.9 mu g/mL and limits of quantification were 4.76 mu g/mL, 2.73 mu g/mL for UVD and ECD methods, respectively. Precision and accuracy of the methods were obtained <= 10.9 % (RSD), <= 11.5% (RE). The recoveries were found 108 +/- 6% and 102 +/- 7% for UVD and ECD methods, respectively. A strong, positive and linear correlation was found between hydroxyproline values obtained from UVD and ECD methods (p<0.01, r=+0.98). After optimization and validation of these methods, OHP levels in urine samples which were obtained from non-smokers and smokers were analyzed and, observed OHP/creatinine levels were compared. Results of both methods showed that total urinary OHP values of smokers were significantly higher than non-smokers (p<0.05).
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    Development and validation an HPLC - UV method for determination of esomeprazole and pirfenidone simultaneously in rat plasma: application to a drug monitoring study
    (İstanbul Üniversitesi, 2021) Dural, Emrah; Köz, Sema Tülay; Köz, Süleyman
    Background and Aims: It has been observed that the combined treatment of esomeprazole and pirfenidone provides increased efficacy in the treatment of pulmonary fibrosis disease, recently. The aim of this study is to develop a simple, sensitive, and reliable high-performance liquid chromatography method to be used in drug monitoring to increase the effectiveness of esomeprazole and pirfenidone in treatment and to reduce their adverse effects. Methods: Separation was conducted with a C18 reverse-phase column (4.6 mm x 250 mm, 5 μm) used as a mobile phase prepared with the phosphate buffer (10 mM KH2PO4 and 10 mM K2HPO4) and acetonitrile (60:40, v/v) by an isocratic flow (1 mL/min). Mobile phase pH was adjusted to 3.0. Ultraviolet detection was accomplished at 305 nm. The column oven was held at 35°C to ensure an efficient analytical separation. Results: Analytical recovery of esomeprazole was between 92.43 and 105.36% and for pirfenidone it was found between 89.56 and 104.32%. Accuracy values of esomeprazole and pirfenidone were determined between (-2.90) – 4.22 and (-4.45) – 5.78, respectively. Precision (RSD%) was ≤7.89. The quantification limit was determined as 0.58 and 0.36 ng/mL. Plasma esomeprazole and pirfenidone levels were found as 0.87-8296.87 ng/mL (612.99±2212.20, mean ± standard deviation) and 0.45-238.60 ng/mL (61.44±76.35, mean ± standard deviation), respectively. Conclusion: Unexpectedly high RSD values were observed in both plasma (360.88%) and dose-rated results (89.61%) of esomeprazole, and pirfenidone were thought to be related to individual metabolism differences.
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    Development and validation an HPLC-UV method for determination of esomeprazole and pirfenidone simultaneously in rat plasma: application to a drug monitoring study
    (Istanbul Univ, Fac Pharmacy, 2021) Dural, Emrah; Koz, Sema Tulay; Koz, Suleyman
    Background and Aims: It has been observed that the combined treatment of esomeprazole and pirfenidone provides increased efficacy in the treatment of pulmonary fibrosis disease, recently. The aim of this study is to develop a simple, sensitive, and reliable high-performance liquid chromatography method to be used in drug monitoring to increase the effectiveness of esomeprazole and pirfenidone in treatment and to reduce their adverse effects. Methods: Separation was conducted with a C18 reverse-phase column (4.6 mm x 250 mm, 5 mu m) used as a mobile phase prepared with the phosphate buffer (10 mM KH2PO4 and 10 mM K2HPO4) and acetonitrile (60:40, v/v) by an isocratic flow (1 mL/min). Mobile phase pH was adjusted to 3.0. Ultraviolet detection was accomplished at 305 nm. The column oven was held at 35 degrees C to ensure an efficient analytical separation. Results: Analytical recovery of esomeprazole was between 92.43 and 105.36% and for pirfenidone it was found between 89.56 and 104.32%. Accuracy values of esomeprazole and pirfenidone were determined between (-2.90) - 4.22 and (-4.45) - 5.78, respectively. Precision (RSD%) was <= 7.89. The quantification limit was determined as 0.58 and 0.36 ng/mL. Plasma esomeprazole and pirfenidone levels were found as 0.87-8296.87 ng/mL (612.99 +/- 2212.20, mean +/- standard deviation) and 0.45-238.60 ng/mL (61.44 +/- 76.35, mean +/- standard deviation), respectively. Conclusion: Unexpectedly high RSD values were observed in both plasma (360.88%) and dose-rated results (89.61%) of esomeprazole, and pirfenidone were thought to be related to individual metabolism differences.
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    Development and validation of an HPLC method for determination of carbamazepine in human plasma and applications to a therapeutic drug monitoring study
    (Istanbul Univ, Fac Pharmacy, 2020) Dural, Emrah; Cetin, Suleyman; Bolayir, Asli; Cigdem, Burhanettin
    Background and Aims: Carbamazepine (CBZ) is an antiepileptic drug, which is prescribed as a first-line drug for the treatment of partial and generalized tonic-clonic epileptic seizures. The aim of this study was to develop and validate a simple, fast and reliable HPLC method for the determination of carbamazepine in human plasma. Methods: Chlorpromazine (CPR) was used as an internal standard. The separation was conducted with a C18 reverse-phase column (150x3.9 mm, 5 mu m) at 30 degrees C, using a mobile phase prepared with 20 mM KH2PO4, acetonitrile and methanol (6:3:1, v/v/v) by isocratic elution. Results: The method was linear between 0.5 and 40 mu g/mL, determined by 10 individual calibration points. Total run time was <= 5 mins. Accuracy (RE%) values were determined between (-5.6) and 3.6%, and precision was determined at <= 4.2%. Limit of detection (LOD) was 0.04 mu g/mL. The robustness test results of the method showed good values. Plasma CBZ of (n=30) those receiving CBZ quantities ranging from 0.2 to 1.2 g/day were measured with this method, and following analyses of their concentrations were found to be between 0.1 and 11.4 mu g/mL (6.2 +/- 2.4 mu g/mL). While all plasma sample analyses were applied properly, it was observed that 16 (53.3%) of the plasma samples had CBZ lower than the recommended range. In addition to that, female patient plasma-CBZ levels were found significantly higher than male plasma contents (p<0.05). Conclusion: This method was found suitable for the analysis of plasma samples collected during the therapeutic drug monitoring (TDM) of patients treated with CBZ.
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    Development and Validation of HPLC-UV Method for the Determination of Diclofenac in Human Plasma with Application to a Pharmacokinetic Study
    (TURKISH PHARMACISTS ASSOC, 2016) Arisoy, Gulsum Gul; Dural, Emrah; Mergen, Gorkem; Arisoy, Mustafa; Guvendik, Gulin; Soylemezoglu, Tulin
    A simple, rapid and reliable high performance liquid chromatography method (HPLC) with ultraviolet detection (UV) was developed and validated according to ICH guidelines, for quantitative analysis and therapeutic drug monitoring of diclofenac sodium (DS) in human plasma. Plasma samples (0.7 mL) were acid hydrolysis by 100 mu L, 1 M hydrochloric acid. Analytes were concentrated from plasma by liquid-liquid extraction with 2 mL ethyl acetate by repeated twice, which allows to obtain good extraction yields (98.75%-99.32%). The separation was achieved by employing C18 analytical column (3.5 mu m particle size, 150 mmx3.9 mm I.D.) under isocratic conditions using acetonitrile and NaH2PO4 mixture (42.5: 57.5, v/v) as mobile phase (pH: 3.16) flow rate of 1.5 mL/min. Naproxen (3 mu g/mL) was used as an internal standard (IS). The DS and IS were detected at 281 nm and eluted at 2.6 and 6.2 min, respectively. Total run time was 7 min. Method showed linearity with very good determination coefficients (r(2)=0.999), over the concentration range of 50 - 1600 ng/mL. Limits of detection (LOD) and quantification (LOQ) were 8.95 ng/mL and 27.12 ng/mL, respectively. Intra-day precision and accuracy were between 0.93-5.27; 1.74-9.81, respectively. Inter-day precision and accuracy were between 2.71-6.64; 2.03-9.16, respectively. This method was successfully applied for determination of DS plasma concentrations during a pharmacokinetic study in healthy volunteers (n=12) after an oral administration of Voltaren (R) 75 mg/tablet and remarkable variations in DS levels were observed. In our study, on the contrary to equivalent doses of DS, the observed significant differences in plasma levels of DS, on 2nd, 4th and 6th hours, can be explained by pharmacokinetic differences, that arise from mainly polymorphisms of CYP2C9 and CYP3A4, which are major enzymes responsible for DS metabolism.
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    Development of a liquid chromatographic method to monitorization of medazepam and lorazepam in plasma and its validation
    (Istanbul Medipol University, 2023) Alpertenge, Melike; Dural, Emrah
    This study, it was aimed to develop a simple, sensitive and reliable high-performance liquid chromatographic method for simultaneous analysis of medazepam and lorazepam based on the solid-phase extraction from human blood. For the pretreatment of (500 µL) plasma sample, an efficient extraction method was developed and optimized. Separation was carried out with an ODS reverse phase C18 analytical column (150x4.0mm, 3µm). The composition of 20 mM KH2PO4 buffer and methyl cyanide (6:4, v/v) was employed as the mobile phase in the chromatographic system. The ultraviolet detector was set at 220nm. Determination of coefficients values was found as 0.9928 (r2) between 500-2500 ng/mL concentrations for medazepam and 0.9983 between 20-300 ng/mL for lorazepam. It was observed that the method has successful validation test results from accuracy, sensitivity, recovery, precision, and robustness in accordance with ICH Q2R1 guidelines. The method is recommended for monitoring blood levels of lorazepam and medazepam in toxicology laboratories. © 2023, Istanbul Medipol University. All rights reserved.
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    In-vitro antioxidant, a-glucosidase and a-amylase inhibitory activities of crude ethanol extract and fractions of endemic Hya cinthella a cutil Oba K.Perss. & Wendelbo bulbus
    (Parlar Scientific Publications, 2019) Eruygur, Nuraniye; Dural, Emrah; Tekin, Mehmet; Ozpinar, Hulya
    In the present study, the antioxidant potential as well as the ?-amylase and ?-glucosidase inhibitory activity of different extracts of Hyacinthella acutiloba bulbus were investigated using an in vitro model. Antioxidant activity was assayed by the DPPH radical scavenging activity, total phenol content (TPC) and total flavonoid content (TFC), reducing power assay, ferric thiocyanate (FTC) and thiobarbituric acid method (TBA). Among the extracts, n-hexane and chloroform extract of H. acutiloba displayed more activity than other extracts against ?- amylase and a-glucosidase. © 2019 Parlar Scientific Publications. All rights reserved.
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    IN-VITRO ANTIOXIDANT, A-GLUCOSIDASE AND A-AMYLASE INHIBITORY ACTIVITIES OF CRUDE ETHANOL EXTRACT AND FRACTIONS OF ENDEMIC HYACINTHELLA ACUTILOBA K.PERSS. & WENDELBO BULBUS
    (PARLAR SCIENTIFIC PUBLICATIONS (P S P), 2019) Eruygur, Nuraniye; Dural, Emrah; Tekin, Mehmet; Ozpinar, Hulya
    In the present study, the antioxidant potential as well as the alpha-amylase and alpha-glucosidase inhibitory activity of different extracts of Hyacinthella acutiloba bulbus were investigated using an in vitro model. Antioxidant activity was assayed by the DPPH radical scavenging activity, total phenol content (TPC) and total flavonoid content (TFC), reducing power assay, ferric thiocyanate (FTC) and thiobarbituric acid method (TBA). Among the extracts, n-hexane and chloroform extract of H. acutiloba displayed more activity than other extracts against a amylase and alpha-glucosidase.
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    Investigation of the Presence of Sildenafil in Herbal Dietary Supplements by Validated HPLC Method
    (Turkish Pharmacists Assoc, 2020) Dural, Emrah
    Objectives: As the first FDA-approved phosphodiesterase type 5 inhibitor, sildenafil (SDF) is widely used in the treatment of erectile dysfunction due to its strong pharmacodynamic activity. Since many food supplements are now involved in illegal adulteration, the presence of SDF in food supplements is very important because of their toxicological risks. In this study a simple fast, reliable high-performance liquid chromatography method with ultraviolet (UV) detector has been developed and validated for SDF analysis in herbal dietary supplements (HDSs). Materials and Methods: 10 mM phosphate buffer containing 0.1% triethylamine (pH 3.5) and acetonitrile (65:35, v/v), as mobile phase was applied isocratically to a reverse phase C-18 analytical (4.6x250 mm, 5 pm) column. Chromatographic separation was achieved by a C I , reverse-phase analytical column 4.6x250 mm, 5 mu m particle size, using acetonitrile, with 10 mM phosphate buffer containing 0.1% triethylamine (65:35, v/v, pH 3.5) as a mobile phase. The mobile phase flow rate was 1 mL min(-1) and the column temperature was 35 degrees C. The UV detector was set at 293 nm. The liquid-liquid extraction method used in the study provided a simple and practical method for the recovery of SDF in HDSs and their obtained values ranged from 87.6 to 111.7%. Results: The method showed linearity with an excellent correlation coefficient (r(2) >0.999). Moreover, it was specific and sensitive with the limit of quantification, 6.5 ng mL(-1). Intraday and interday method precision was 58.2 (relative standard deviation %). Intraday and interday method accuracy was between -4.0 and 7.1 (RE%). The method was strong according to the robustness test results obtained from UV detection, mobile phase buffer pH, column temperature, and flow rate changes. The described procedure was simple, fast, precise, and feasible for routine adulteration analysis of SDF, especially in food control or toxicology laboratories. This method was successfully applied to 50 individual solid and liquid form HDSs. Conclusion: The results showed that 37 out of 50 samples of HDSs (represented 74.0%) examined contained SDF between 0.01 and 465.47 mg/g, 150.87 +/- 127.48 (mean +/- standard deviation), which could lead to serious health problems and might even be fatal for consumers. The described procedure was found to be simple, rapid, precise and feasible for routine adulteration analysis of SDF, especially in food control or toxicology laboratories.