Nafiz Oncu Can

The determination of levofloxacin by flow injection analysis using UV detection, potentiometry, and conductometry in pharmaceutical preparations

A flow injection analysis (FIA) using UV detection, potentiometry and conductometry for levofloxacin (LVF) are described in this study. The best solvent system was found to consist of 0.2 M acetate buffer at pH 3 having 10% MeOH. A flow rate of 1 ml min(-1) was pumped and active material was detected at 288 nm. The detection limit (LOD) and limit of quantification (LOQ) for FIA were calculated to be 3 x 10(-7) M (S/N = 3) and 1 x 10(-7) M (S/N = 10), respectively. In the analysis of tablets, the RSD values were found to be 0.83, 0.98 and 0.99 for FIA, potentiometric and conductometric methods, respectively.

A novel RP-HPLC method for simultaneous determination of potassium sorbate and sodium benzoate in soft drinks using C18-bonded monolithic silica column

Potassium sorbate and sodium benzoate are food additives that are generally employed for prevention of food spoilage originating from bacteria, molds or yeasts. Although these compounds were generally recognized as safe due to their low risk of acute and chronic toxicity, they have limitations of usage to protect human health. Development and validation of a novel RP-HPLC method, in which a C18-bonded monolithic silica column was used as stationary phase to assay these compounds, is described for the first time. Aliquots of 10 μL of samples were injected into chromatograph and eluted using phosphate buffer (0.025 M, pH 2.0)-water-acetonitrile (50:45:5, v/v/v) solution, which was pumped at the rate of 3.0 mL/min. To sharpen the peaks, 10 mM octylamine was added to the mobile phase. Potassium sorbate and sodium benzoate were detected at about 12(th) and 14(th) min, respectively, and quantified at 230 nm using photodiode array detector. A total of 41 samples were prepared by simply filtering through 0.45 μm filters after sonication, and injected into the system without any pre-treatment steps. Applicability of the method was demonstrated by performing total procedure on samples of different brands and types, and their compliance to official regulations was assessed.

Synthesis of New Hydrazone Derivatives for MAO Enzymes Inhibitory Activity

In the present work, 14 new 1-substituted-2-phenylhydrazone derivatives were synthesized to evaluate their inhibitory activity against hMAO enzymes. The structures of the newly synthesized hydrazones 2a–2n were characterized by IR, 1H-NMR, 13C-NMR, HR-MS spectroscopic methods. The inhibitory activity of compounds 2a–2n against hMAO-A and hMAO-B enzymes was elucidated by using an in-vitro Amplex Red® reagent assay based on fluorometric methods. According to the activity studies, 2a and 2b were found to be the most active compounds against hMAO-A enzyme, with IC50 values of 0.342 µM and 0.028 µM, respectively. The most active compounds 2a–2b were evaluated by means of enzyme kinetics and docking studies. Moreover, these compounds were subjected to cytotoxicity and genotoxicity tests to establish their preliminary toxicological profiles and were found to be non-cytotoxic and non-genotoxic. Consequently, the findings of this study display the biological importance of compounds 2a, 2b as selective, irreversible and competitive inhibitors of hMAO-A. Docking studies revealed that there is a strong interaction between hMAO-A and the most active compound 2b.

HPLC determination of cefprozil in tablets using monolithic and C18 silica columns.

Cefprozil (CPZ) is a second-generation semi-synthetic cephalosporin antibiotic that commonly exists as the mixture of Z and E diastereoisomers, at the ratio of approximately 9:1. A novel reversed-phase HPLC method for the determination of CPZ in tablets was described. The separation of CPZ diastereoisomers and caffeine (internal standard) was carried out by applying the same analytical and instrumental conditions on two stationary phases, which have different surface chemistries. The columns used in the study were monolithic silica Merck Chromolith Performance RP-18e and conventional C18 silica Phenomenex Synergi Hydro RP columns. In total, 10 μL aliquots of samples were injected into the system and eluted using water-acetonitrile (90:10, v/v) solution, which was pumped through the column at a flow rate of 1.0 mL/min. The analyte peaks were detected at 200 nm using diode array detector with high specificity. CPZ diastereoisomers and caffeine were measured within 13 min using the C18 column, whereas <5 min was required for the monolithic one. Validation studies were performed according to official recommendations. Value of a monolithic column for the assay of diastereoisomers in pharmaceutical tablets was evaluated for the first time and found as a powerful alternative to highly efficient C18 columns.

Determination of Ticlopidine in Pharmaceutical Tablets by Flow Injection Analysis Using UV-Detection

Abstract A precise and accurate flow injection analysis method for the quantification of ticlopidine in pharmaceuticals is described. An aqueous carrier stream, which was entirely prepared with water was chosen for the flow injection analysis. The method development was achieved by using a reference standard solution of ticlopidine at 3.19 × 10−6 M concentration, which was prepared in water. The solution was injected into the instrumental system at a flow rate of 1.0 mL·min−1 and signals were detected by a UV detector at 214.2 nm. The calibration curves of TP were linear in the concentration range of 1.59 × 10−6 − 7.99 × 10−5 M. The intra- and inter-assay precision was less than 1.3% relative standard deviation. The method exhibited good linearity with the correlation coefficients close to unity. The limit of detection and limit of quantization concentrations were found to be 8.91 × 10−8 and 2.70 × 10−7 M, respectively. The effects of the tablet excipients were insignificant at the 95% probability level. The calculated tablet contents were around 99%, which is in agreement with the ranges stated by pharmacopoeias.

Determination of Azapropazone in its Pharmaceutical Form by HPLC and Flow Injection Analysis

Abstract Azapropazone is an analgesic and anti‐inflammatory agent that is used in the treatment of musculoskeletal and joint disorders, as well as in acute gout, because of its uricosuric properties. A simple and sensitive high performance liquid chromatographic method (HPLC), for the determination of azapropazone in its pharmaceutical form has been developed and validated. Azapropazone and indapamide (internal standard) were separated by a reversed phase column (Supelco Hypersil 5 µm, 150×4.6 mm ID, C18) with a mobile phase consisting of K2HPO4 (0.1 M) and methanol (55∶45, v/v) (at pH 7.0). The mobile phase was pumped at 1.2 mL min−1 flow rate then azapropazone was determined by ultraviolet detection at 251 nm. The method has an average analysis time of 5.81 min. for azapropazone. The flow injection analysis (FIA) was performed by using a carrier stream of ethanol∶water (10∶90, v/v) with a flow rate of 1.2 mL min−1. The LOD and LOQ concentrations of azapropazone for the two methods were 2.77×10−8 M and 8.41×10−8 M for HPLC, 3.65×10−7 M and 1.10×10−6 M for FIA, respectively. The results obtained from the analysis of capsule samples using both methods were compared by common statistical tests. There was no significant difference observed between the methods.

Validated Reversed Phase HPLC Method for the Analysis of the Food Additive, Sodium Benzoate, in Soft Drinks and Jams

Abstract A rapid, simple, and sensitive method is described for the determination of the food preservative sodium benzoate in soft drinks, various jams, and ketchup. The method utilizes high performance liquid chromatography followed by diode array detection. Chromatographic separation was achieved using a C18 reversed phase column and methanol: water (70∶30, v/v) adjusted to pH 3.45 with glacial acetic acid as mobile phase, 0.45 mL . min−1 flow rate, and UV detection at 245 nm. Amoxicillin was used as the internal standard. The retention time observed for sodium benzoate and amoxicillin were 5.01 and 12.07 min, respectively. The method is selective, reliable, and reproducible with a relative standard deviation of 0.66 and linear in the range of 50–450 ng/mL sodium benzoate concentration. The limit of detection and limit of quantification concentrations were 61 pg/mL and 203 pg/mL, respectively. The proposed method can be used for the routine analysis of sodium benzoate in soft drinks and jams.

Determination of amoxicillin by flow injection analysis using UV-detection, potentiometry, and conductometry in pharmaceutical preparations

Abstract A method for direct determination of amoxicillin in pharmaceuticals using flow injection analysis (FIA) with UV detection adjusted at 228 nm, along with potentiometer and condoptometric methods are described. The best carrier solvent system consisted of an aqueous solution of methanol (10% v/v) with pH 9 pumped at a flow rate of 1 mL · min−1. The limit of detection (LOD) and quantification (LOQ) for FIA was calculated to be 3.3×10−7 M (S/N=3) and 1.0×10−7 M (S/N=10), respectively. Two pharmaceutical formulations containing amoxicillin were studied. In the analysis of the tablets, the RSD values were found to be 1.36 and 1.21 and 1.18 (for AMOKLAVIN®), 1.10 1.16 and 1.14 (for REMOXIL®) for FIA, potentiometer, and conduct metric methods, respectively. The proposed methods were applied to the pharmaceutical tablets and good results were obtained. These proposed methods are simple, fast, accurate, precise, and cost effective for the routine determination of amoxicillin in pharmaceutical preparations.

Synthesis of Some Novel Thiadiazole Derivative Compounds and Screening Their Antidepressant-Like Activities

Novel thiadiazole derivatives were synthesized through the reaction of acetylated 2-aminothiadiazole and piperazine derivatives. The chemical structures of the compounds were clarified by Infrared Spectroscopy (IR), 1H Nuclear Magnetic Resonance Spectroscopy (1H-NMR), 13C Nuclear Magnetic Resonance Spectroscopy (13C-NMR) and Electronspray Ionisation Mass Spectroscopy (ESI-MS) spectroscopic methods. Antidepressant-like activities were evaluated by the tail-suspension (TST) and modified forced swimming (MFST) methods. Besides, possible influence of the test compounds on motor activities of the animals were examined by activity cage tests. In the TST, administration of the compounds 2c, 2d, 2e, 2f, 2g and 2h significantly decreased the immobility time of mice regarding the control values. Further, in the MFST, the same compounds reduced the total number of immobility behaviors while increasing swimming performance. However, no change was observed in the total number of climbing behaviors. These data suggested that compounds 2c, 2d, 2e, 2f, 2g and 2h possess notable antidepressant-like activities. Reference drug fluoxetine (10 mg/kg) was also exhibited its antidepressant activity, as expected. No significant difference was seen between the locomotor activity values of the test groups signifying that observed antidepressant-like activities are specific. Theoretical calculation of absorption, distribution, metabolism, excretion (ADME) properties for the obtained compounds were performed and obtained data supported the antidepressant-like potential of these novel thiadiazole derivatives.

ANALYSIS OF ACRYLAMIDE IN TRADITIONAL AND NONTRADITIONAL FOODS IN TURKEY USING HPLC–DAD WITH SPE CLEANUP

Acrylamide is a heat-generated food toxicant, which exists in various foodstuffs such as potato chips, biscuits, and coffee. It has been demonstrated that acrylamide possesses some neurotoxic and carcinogenic effects and is classified in Group 2A as a probable carcinogen to humans by International Agency for Research on Cancer. The aim of this study was to develop a rapid, robust, and sensitive high performance liquid chromatography (HPLC) method and indicate acrylamide levels of some traditional and nontraditional foods consumed in Turkey. Acrylamide content of samples was determined using HPLC coupled to photodiode array detection. Acrylamide and methacrylamide (internal standard) were separated using an ODS-3 reversed phase column in isocratic elution mode. The mobile phase (acetonitrile: water, 2:98, v/v) was pumped at 0.5 mL/min flow rate and the analytes were detected at 200 nm wavelength within 15 min. Samples were prepared by utilizing Oasis HLB (Waters) solid phase extraction cartridges for clean-up and analyzed with no further preconcentration steps. As a result, it was observed that the amount of acrylamide in traditional Turkish foods was found to be relatively low in many of the samples, especially in desserts although they are exposed to heat in their preparation.