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Now showing 1 - 10 of 18
  • PublicationMetadata only
    Simultaneous determination of hydrochlorothiazide, amlodipine, and telmisartan with spectrophotometric and HPLC green chemistry applications.
    (2022-06-03T00:00:00Z) Tiris, GİZEM; Mehmandoust, Mohammad; Lotfy, Hayam M; Erk, Nevin; Joo, Sang-Woo; Dragoi, Elena-Niculina; Vasseghian, Yasser; TIRIS, GİZEM
  • PublicationMetadata only
    Determination of active ingredients in antihypertensive drugs using a novel green HPLC method approach
    (2022-09-01T00:00:00Z) TIRIS, GİZEM; Mehmandoust, Amirhossein; Karimi, Fatemeh; ERK, NEVİN; TIRIS, GİZEM
    © 2022 Elsevier LtdA novel, sensitive, fast, and pratic RP-HPLC methods were presented for the quantitative amounts of Telmisartan (TEL) and Olmesartan (OLM) in the presence of Amlodipin (AML) in a binary mixture of pharmaceutical preparation. Waters Spherisorb ODS-2 C18 column was used for separation. These methods were valid over linearity ranges of 2.5–30 μμg/mlL, 2–85 μμg/mlL, and 2–35 μμg/mlL for OLM, TEL, and AML, respectively. The mobile phase system consisted of acetonitrile:methanol: phosphate buffer at pH 3.0 (65:5:30 v/v/v), and the flow rate was 1,5 mlL/min for OLM and AML. The mobile system-s other mixture (TEL and AML) was acetonitrile:methanol: phosphate buffer at pH 2.5 (65:5:30 v/v/v), and the flow rate was 1,5 mlL/min. These procedures were successfully applied to bulk, laboratory synthetic mixture, and medicinal dosage forms to use active ingredients quantitatively. The studied methods were validated according to ICH guidelines. In the developed HPLC method, the limit of detection values was found to be 0.020 μμg/mlL for TEL, 0.025 μμg/mlL for OML, and 0.070 μμg/mlL for AML. The correlation coefficients for the HPLC method were found to be 0.9938 for TEL, 0.9996 for OML, and 0.9982 for AML. The calibration range is between 2.5 and -30, 5–35, and 2–85 μμg/mlL for OLM, AML, and TEL, respectively. The proposed HPLC method is a convenient, effective, sensitive, green, and time-saving method for the rapid determination of TEL and OLM in the presence of AML.
  • PublicationOpen Access
    Novel approaches for determination of antiretroviral reverse transcriptase inhibitor agent in commercial dosage forms by using spectrofluorimetric, first derivative spectrophotometric, and HPLC methods
    (2020-09-01T00:00:00Z) Tiris, Gizem; Ciloglu, Emine; ERK, NEVİN; TIRIS, GİZEM
    Background: Rapid, simple, and sensitive spectrofluorimetric, first derivative spectrophotometric, and high-performance liquid chromatographic (HPLC) methods have been developed and validated for determination of tenofovir in pharmaceutical preparations. Spectrofluorimetric method is based on measuring the native fluorescence intensity of tenofovir at 375.0 nm after excitation at 275.0 nm. Calibration graphics were plotted and were found linear over 4.72-15.75 mu g/mL concentration range (r(2)= 0.9994). The second method developed was the first derivative spectrophotometric method for the analysis of tenofovir performed by measuring the amplitude at 251.7 and 272.6 nm. Linearity was observed in the concentration range 10.0-28.0 mu g/mL (r(2)= 0.9998). On the other hand, HPLC with a diode array detector (DAD). Ritonavir was used as internal standard (IS). HPLC analysis was carried out on a C(18)column (Wakosil-II 5 C-18 AR, 4.6 x 250 mm) using a mobile phase consisting of acetonitrile: 0.5% formic acid (99.5:0.5; v/v) at a flow rate of 1.0 mL/min. Injection volume was 5.0 mu L. DAD signals at 260.0 nm were used. HPLC method was found to be linear over the concentration range of 10.0-100.0 mu g/mL (r(2)= 0.9990).
  • PublicationMetadata only
    A novel stability-indicating method for determination of a new antidepressant effect of vortioxetine in a pharmaceutical formulation by using RP-HPLC
    (2020-12-01T00:00:00Z) TIRIS, GİZEM; Alver, Cansu; ERK, NEVİN; TIRIS, GİZEM
    Background: A novel rapid, accurate, and stability-indicating reversed-phase high performance liquid chromatographic (RP-HPLC) and first derivative spectrophotometric determination were explained for the assay of vortioxetine (VRT) in bulk and pharmaceutical formulations. For RP-HPLC method, optimal separation and determination of VRT were achieved with a Waters Symmetry C-18, (100 x 4.6 mm, 3.5 mu m) analytical column using a mobile phase consisting of methanol:0.05 M potassium dihydrogen phosphate (pH:3.0 +/- 0.05) (30:70, v/v) in isocratic mode with flow rate of 1.3 mL min(-1). Injection volume was 20 mu L. The maximum absorption wavelength of VRT is 225.0 nm; hence, 225.0 nm was studied as the detection wavelength and column at 50 degrees C temperature. The caffeine was used as the internal standard (IS). On the other hand, the first derivative spectrophotometric method for the analysis of vortioxetine was performed by measuring the amplitude at 251.7 and 272.6 nm.
  • PublicationMetadata only
    Çocuklarda Dikkat Eksikliği Hiperaktivite Bozukluğu Durumunda Kullanılan İlaçlar, Gıda Takviyeleri ve Fitofarmasötiklerin İncelenmesi
    (2021-11-17T00:00:00Z) Tekkeli, Şerife Evrim; Özbek, Emirhan; TIRIS, GİZEM; TEKKELİ, ŞERİFE EVRİM
  • PublicationMetadata only
    Electrochemical Determination of Sunset Yellow in river water and some food samples
    (2022-09-08T00:00:00Z) Tırıs, Gizem; Oven, Elifnaz; Mehmandoust, Mohammad; Erk, Nevin; Soylak, Mustafa; TIRIS, GİZEM
  • PublicationMetadata only
    A new HPLC method for the determination of Allicin and S-Allyl cysteine in garlic (Allium sativum L.) extracts
  • PublicationMetadata only
    The power of High Impact Amplitude Manipulation (HIAM) technique for extracting the basic spectra of two Fixed-dose combinations (FDC) -Spectrophotometric purity analysis via spectral contrast angle
    (2022-05-15T00:00:00Z) Saleh, Sarah S.; Lotfy, Hayam M.; TIRIS, GİZEM; ERK, NEVİN; El-Naem, Omnia A.; TIRIS, GİZEM
    © 2022 Elsevier B.V.HIAM technique allows the extraction of the original constant signal of each single component out of interference signals of a mixture and further transformed into basic spectrum (D0). It includes the methods: ratio subtraction coupled with unified constant subtraction (RS-UCS), constant center (CC) and constant extraction (CE). The technique was introduced for the analysis of two pharmaceutical formulations used to treat cardiovascular diseases. The formulations are binary combinations of Amlodipine (AML) with either Atorvastatin (ATR) or Candesartan (CND) which shows interefernce absorbance signals. The technique was valid over the linearity range of (5.0–35.0 µg/ml) for AML, ATR and CND with recovery percentage 100.40 ± 1.88, 100.00 ± 0.86 and 99.83 ± 1.07, respectively. The extracted signals were tested for its purity by spectral contrast angle (cos θ) to illustrate the efficency of the HIAM technique where cos θ values ranges from (0.9902 to 0.9986). The presented technique was fully validated regarding ICH guidelines and were statistically compared using one-way ANOVA at 95% confidence.
  • PublicationMetadata only
    Determination of dihydrocapsaicin adulteration in dietary supplements using LC-MS/MS
    (2020-01-01T00:00:00Z) DİNCEL, DEMET; Olgan, Hatice; Canbaloglu, Zeynep; Yalcin, Sule; Erkucuk, Aysen; TIRIS, GİZEM; GÖREN, AHMET CEYHAN; DİNCEL, DEMET; TIRIS, GİZEM; GÖREN, AHMET CEYHAN
    Adulterations of dietary supplements are serious threats to public health in all around of world. Nowadays, in order to obtain the intended effect from natural remedies, the adulteration of natural products via artificial or harmful chemicals are increasing. A rapid LC-MS/MS method for determination of capsaicin and dihydrocapsaicin in dietary supplements via Fortis C18 (150 x 3 mm; 3 mu m) column at 25 degrees C was developed and validated in a mixture of mobile phase A (1 % formic acid solution and 0.1 % ammonium formate in water) and B (1 % formic acid solution and 0.1 % ammonium formate in methanol) with gradient program at a flow rate of 0.35 mL/min. The recoveries of developed methods weytre obtained in the range of % 95.4-106.3 for capsaicin and % 96.3-108.9 for dihydrocapsaicin. This study shows that synthetic compound dihydrocapsaicin is widely use in dietary supplements products for adulteration to increase the effects of product without any declaration.
  • PublicationMetadata only
    (2021-06-25T00:00:00Z) Mehmandoust, Mohammed; Erk, Nevin; Tırıs, Gizem; TIRIS, GİZEM