Yucel Kadioglu

A study of spontaneous combustion characteristics of a turkish lignite: particle size, moisture of coal, humidity of air

This study evaluated the spontaneous combustion characteristics of Askale lignite from Turkey. The effect of the gas flow rate, the moisture of the piles of coal, the humidity of the air and particle size on the spontaneous combustion characteristics of coal samples were examined using Crossing Point Methods adapted to our laboratories conditions. The amounts of three predominant oxygen functional groups (carboxyl, hydroxyl and carbonyl) in untreated and moist coal samples were also determined with wet chemical methods. The amounts of oxygen functional groups in moist coal samples do not differ significantly from that of untreated coal. The liability of spontaneous combustion of this lignite was increased with decreasing particle size, increasing moisture content of the coal and decreasing humidity of the air.

The effect of moisture content and air-drying on spontaneous combustion characteristics of two Turkish lignitesa

The results of an experimental study aimed at evaluating the spontaneous combustion characteristics of two Turkish lignites moistured and air-dried at varying times are discussed. The spontaneous combustion characteristics of the coals were determined using Crossing Point Methods adapted to our laboratories conditions. The content of three predominant oxygen functional groups (carboxyl, hydroxyl, and carbonyl) of untreated, moisten and air-dried coal samples were also determined with wet chemical methods. The content of oxygen functional groups in moisten coal samples do not differ significantly that of untreated coal samples, for realized in vacuum desicator to moistured of coal samples. The liability of spontaneous combustion of the two coals was reduced when moisture content increased with increase in contacted time to water vapour. The moisten coal samples was dried in laboratory during 24 and 48 h time period. The concentration of oxygen contain functional groups of drying coal samples increased with increase of contact time with air and decrease of particle size. The liability of spontaneous combustion of the air-dried coal samples increased with increase of contacted time with air and with decrease of moisture content.

Pharmacokinetics of florfenicol after intravenous and intramuscular administration in New Zealand White rabbits

The pharmacokinetic disposition and bioavailability of florfenicol (FF) were determined after single intravenous (i.v.) and intramuscular (i.m.) administrations of 25mg/kg b.w. to ten healthy New Zealand White rabbits. Plasma FF concentrations were determined by high-performance liquid chromatography (HPLC). The plasma pharmacokinetic values for FF were best described by a one-compartment open model. The elimination half-life (t(1/2beta)) was different (p<0.05) however, the area under curve (AUC) was similar (p>0.05) after i.v. and i.m. administrations. FF was rapidly eliminated (t(1/2beta) 1.49+/-0.23 h), slowly absorbed and high (F, 88.75+/-0.22%) after i.m. injection. In addition, FF was widely distributed to the body tissues (V(ss) 0.98+/-0.05 L/kg) after i.v. injection. In this study the time that plasma concentration exceeded the concentration of 2 microg/mL was approximately 6h. For bacteria with MIC of 2 microg/mL, frequent administration at this dose would be needed to maintain the concentration above the MIC. However, it is possible that rabbit pathogens may have MIC values less than 2 microg/mL which would allow for less frequent administration. Further studies are necessary to identify the range of MIC values for rabbit pathogens and to identify the most appropriate PK-PD parameter needed to predict an effective dose.

Simultaneous determination of gemcitabine and its metabolite in human plasma by high-performance liquid chromatography

Gemcitabine (dFdC) is a pyrimidine antimetabolite with broad spectrum activity against tumors. In this paper, a normal-phase high-performance liquid chromatographic method was developed for the determination of the parent drug (dFdC) and its metabolite (dFdU) in human plasma. The described sample preparation procedure for determination of dFdC and dFdU is rapid, sensitive, reproducible and simple. The linear regression equations obtained by least square regression method, were area under the curve=0.0371 concentration (ng ml(-1))+192.53 and 1.05.10(-4) concentration (ng ml(-1))-1.2693 for dFdC and dFdU, respectively. The assay for dFdC and dFdU described in the present report has been applied to plasma samples from a bladder cancer patient.

Chlorination kinetics of pyrite mineral in two Turkish lignites

Abstract The kinetics of the chlorination of pyrite in two Turkish lignites in water and water-carbon tetrachloride media at ambient pressure (⋍ 610 mm Hg) are investigated. The effects of speed of stirring (5–20 s −1 ), particle size (74–88, 150–180 and 250–425 μm), temperature (13–70°C) and reaction time (0–18 000 s) were studied. The experimental data were analyzed on the basis of the unreacted shrinking core model. The fine pyrite particles are assumed to be embedded inside the coal particles. The rate-controlling step was found to be diffusion of chlorine through the ash (the coal matrix). The activation energies were calculated as 25.1 kJ mol −1 for Dadagi coal in water medium and 25.0 kJ mol −1 for Mengen coal in water-carbon tetrachloride medium.

Determination of Insulin in Humans with Insulin-Dependent Diabetes Mellitus Patients by HPLC with Diode Array Detection

A simple and reliable high-performance liquid chromatographic method with diode array detection has been developed and validated for the determination of insulin in human plasma. A good chromatographic separation was achieved on a C18 column with a mobile phase consisting of acetonitrile and 0.2M sodium sulfate (pH 2.4), 25:75 (v/v). Its flow rate was 1.2 mL/min. Calibration curve was linear within the concentration range of 0.15-25 µg/mL. Intra-day and inter-day relative standard deviations for insulin in human plasma were less than 6.3 and 8.5%, respectively. The limits of detection and quantification of insulin were 0.10 and 0.15 µg/mL, respectively. Also, this assay was applied to determine the pharmacokinetic parameters of insulin in eight insulin-dependent diabetes mellitus patients after subcutaneous injection of 25 IU of Actrapid HM.

Development and validation of UFLC-MS/MS method for determination of bosentan in rat plasma.

A rapid, simple and sensitive UFLC-MS/MS method was developed and validated for the determination of bosentan in rat plasma using etodolac as an internal standard (IS) after liquid-liquid extraction with diethyl ether-chloroform (4:1, v/v). Bosentan and IS were detected using electrospray ionization in positive ion multiple reaction monitoring mode by monitoring the transitions m/z 551.90→201.90 and 288.20→172.00, respectively. Chromatographic separation was performed on the inertsil ODS-4 column with a gradient mobile phase, which consisted of 0.1% acetic acid with 5mM ammonium acetate in water for solvent A and 5mM ammonium acetate in acetonitrile-methanol (50:50, v/v) for solvent B at a flow rate of 0.3mL/min. The method was sensitive with 0.5ng/mL as the lower limit of quantitation (LLOQ) and the standard calibration curve for bosentan was linear (r>0.997) over the studied concentration range (0.5-2000ng/mL). The proposed method was fully validated by determining specificity, linearity, LLOQ, precision and accuracy, recovery, matrix effect and stability. The validated method was successfully applied to plasma samples obtained from rats.

QUANTITATION OF 17 β-ESTRADIOL IN RABBIT PLASMA BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH FLUORESCENCE DETECTION

A new method was developed for the determination of 17 β-estradiol in rabbit plasma by reversed-phase high performance liquid chromatography (RP-HPLC) with fluorescence (FL) detection. The method employed one-step extraction of 17 β-estradiol from plasma matrix with a mixture of water and ethylacetate (1.9:5, v/v) using estriol as an internal standard. The mobile phase consisted of a mixture of metanol and water (70:30, v/v) flowing at a flow rate of 1.0 mL min−1. Calibration curve was linear between concentration range of 125–6000 ng mL−1. Average recovery of 17 β-estradiol and the internal standard from the biological matrix was more than 94.9 and 92.5%, respectively. The intra-day and inter-day precision and accuracy were between 3.74–8.12 and 3.72–8.80%, respectively. Also, the method was successfully applied to determine of 17 β-estradiol in New Zealand white rabbits.

Continuous Wavelet Transforms for Simultaneous Spectral Determination of Trimethoprim and Sulphamethoxazole in Tablets

A new signal processing approach was developed to improve the simultaneous spectrophotometric determination of trimethoprim (TMP) and sulphamethoxazole (SMX) in their binary mixtures without using any chemical pre-treatment. This approach was essentially based on the continuous wavelet transform (CWT) of the absorption spectra of the target compounds and their samples. A set of continuous wavelet transforms was applied. Biorthogonal with 2.4 order (BIOR2.4), Coiflets with 2 order (COIF2), Daubechies with 3 order (DB3) and Haar (HAAR) were found to be suitable for the quantitative resolution of the twocomponent mixture containing TMP and SMX compounds. The confirmation of the determination results obtained by applying the BIOR2.4, COIF2, DB3 and HAAR wavelet families was achieved by first derivative spectrophotometry (DS1) analysis of the same mixtures. The validation of the above-mentioned signal processing methods was tested by analyzing various binary mixtures of the related compounds, and by using the standard addition technique. The simultaneous determination of TMP and SMX in commercial tablets was assessed by using the proposed signal processing tools.

Pharmacokinetics of florfenicol in the plasma of Japanese quail

Abstract AIM: To determine the pharmacokinetics and bioavailability of florfenicol in the plasma of healthy Japanese quail (Coturnix japonica). METHODS: Sixty-five quail were given an I/V and I/M dose of florfenicol at 30 mg/kg bodyweight (BW). A two-period sequential design was used, with a wash-out period of 2 weeks between the different routes of administration. Concentrations of florfenicol in plasma were determined using high-performance liquid chromatography (HPLC). RESULTS: A naíve pooled data analysis approach for the plasma concentration-time profile of florfenicol was found to fit a non-compartmental open model. After I/V administration, the mean residence time (MRT), mean volume of distribution at steady state (Vss), and total body clearance of florfenicol were 12.0 (SD 0.37) h, 8.7 (SD 0.22) L/kg, and 1.3 (SD 0.08) L/h/kg, respectively. After I/M injection, the MRT, mean absorption time (MAT), and bioavailability were 12.3 (SD 0.37) h, 0.2 (SD 0.02) h, and 79.1 (SD 1.79)%, respectively. CONCLUSIONS: The time for the concentration of florfenicol to fall below the probable effective concentration of 1 µg/ml of approximately 10 h is sufficient for the minimum inhibitory concentration needed for many bacterial isolates. Further pharm acodynamic studies in quail are needed to evaluate a suitable dosage regimen.