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1

Asymptotic behavior of nonoscillatory solutions of higher-order integro-dynamic equations

Bohner M., Grace S., Sultana N.

Opuscula Mathematica

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2014

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Vol. 34, no. 1

5--14

EN

In this paper, we establish some new criteria on the asymptotic behavior of nonoscillatory solutions of higher-order integro-dynamic equations on time scales.

2

Simultaneous determination of fusidic acid and steroids from bulk drugs and human plasma by reversed phase HPLC

Nawaz M., Arayne M. S., Sultana N., Haider A., Hisaindee S.

Acta Chromatographica

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2014

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Vol. 26, no. 1

57--66

EN

A simple, rapid, and sensitive high-performance liquid chromatography method was developed and validated for the simultaneous determination and quantification of fusidic acid and steroids (prednisone, betamethasone valerate, hydrocortisone acetate, and dexamethasone sodium) from bulk drugs and human plasma. A RP-HPLC, operated at ambient temperature, was equipped with a UV detector for monitoring the effluents at 235 nm. The mobile phase consisted of methanol, acetonitrile, and 0.05 M phosphoric acid (10:60:30, v/v/v), and separation was achieved on a Medeterrane, C18 (5 μm, 12.5 × 0.46 mm) column at a flow rate of 1.7 mL min -1. Calibration curves were linear over concentration range 0.625–10 μg mL -1 with correlation coefficient (r2) greater than 0.9999. The coefficient of variation (CV) and relative error (RE) for intra- and interassay were <2% and <1%, respectively. Interference of other already administered common medicaments, such as aspirin, paracetamol, caffeine, nicotine, and other plasma components, were not found.

3

Simultaneous determination of cefpirome, cefaclor, ceftazidime, and cephradine in pharmaceutical formulations by reversed phase HPLC

Nawaz M., Arayne M. S., Sultana N.

Acta Chromatographica

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2011

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Vol. 23, no. 2

205--213

EN

A rapid and sensitive high-performance liquid chromatographic method has been developed and validated for the simultaneous determination and quantification of cephalosporins (cefpirome, cefaclor, ceftazidime, and cephradine) in pharmaceutical formulations. Separation was achieved in the presence of caffeine as internal standard on a Mediterranea C18 (5 μm, 25 × 0.46 mm) column. The mobile phase was composed of methanol and water (30:70), which was pumped at a flow rate of 1 mL min-1. Effluents were monitored at 265 nm. The assay was linear in the concentration range of 0.5–50 μg mL -1, with the correlation coefficient (r2) greater than 0.9998. The intra-day and inter-day coefficients of variation (CV %) were less than 4% at different concentrations.

4

Quantitative determination of fluoroquinolinic antibiotics: pefloxacin, norfloxacin, ciprofloxacin and ofloxacin in pharmaceutical preparations and human serum by high-performance liquid chromatography using multi-wavelength calibration technique

Siddiqui F. A., Arayne M. S., Sultana N., Qureshi F., Mirza A. Z., Shehnaz H.

Chemia Analityczna

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2009

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Vol. 54, No. 6

1465-1485

EN

The objective of this research was to develop and validate an analytical method for quantitative determination of fluoroquinolones using multivariate calibration technique in order to reduce chance errors. Simple and rapid chromatographic method for quantitative determination of four quinolone antibiotics, separately in pharmaceutical formulations and human serum, was developed and validated. The studied fluoroquinolones were pefloxacin, norfloxacin, ciprofloxacin and ofloxacin. These quinolones were analysed using a Nucleosil C18 (10 μrn, 25 cm x 0.46 cm) column, a water-acetonitrile (50:50, v/v) mobile phase of pH 2.9 adjusted with phosphoric acid, and propylparaben as an internal standard. The flow rate was 1.0 mL min1. The analyses were performed at the room temperature (24 š 2°C) using a UV detector at the wavelengths 260,265,270,275 and 280 nm. All fluoroquinolones were separated within 10 min. The calibration curves were linear (≥ 0.9999) over the concentration range 20-10000 ng mL-1. Relative standard deviation (RSD) was 1.56%, minimum recovery was 98.65 % and maximum recovery equaled to 100.81%.

PL

Celem pracy jest opracowanie i walidacja metod ilościowego oznaczania fluorochinolonów przy wykorzystaniu wieloczynnikowej techniki kalibracji, pozwalającej na zminimalizowanie błędu oznaczenia. Opracowano i zwalidowano proste i szybkie metody chromatograficzne ilościowego oznaczania czterech antybiotyków chinolonowych, również w formu-lacjach farmaceutycznych i w ludzkim osoczu. Badane fluorochinolony to pefloksacyna, norfloksacyna. ciprofloksacyna i ofloksacyna. Antybiotyki analizowano stosując kolumnę Nucleosil C18(10μm, 25 x 0,46 cm), jako fazę ruchomą, użyto mieszaninę woda-acetonitryl (50:50, v/v) o pH 2,9 (ustalanym za pomocą kwasu fosforowego) oraz propyloparaben jako wzorzec wewnętrzny. Przepływ wynosił l ,0 mL min-1. Analizy prowadzono w temperaturze pokojowej (24 š 2°C) stosując detektor UV przy długościach fal 260, 265, 270, 275 i 280 nm. Rozdzielenie wszystkich fluorochinolonów uzyskano w ciągu 10 min. Krzywe kalibracyjne były liniowe (r > 0,9999) w zakresie 20 -l 0000 ng mL18. Względne odchylenie standardowe (RSD) było < 1,56%, minimalny odzysk wynosił 98,65% a maksymalny 100,81%.

5

An RP-HPLC method for simultaneous analysis of, and interaction studies on, enalapril maleate and H 2 -receptor antagonists

Sultana N., Arayne M. S., Naveed S., Shamshad H

Acta Chromatographica

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2009

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Vol. 21, no. 4

547--558

EN

A simple, sensitive, and rapid RP-HPLC method for analysis of enalapril in the presence of H 2 -receptor antagonists has been developed and validated. Enalapril maleate was separated from H 2 -receptor antagonists by use of a 250 mm × 4.6 mm, 5-µm particle, C 18 column with 86:14 ( υ / υ ) methanol-water, pH adjusted to 3.5, as mobile phase, at a flow rate of 1.5 mL min -1. UV detection was performed at 227 nm. The retention times of enalapril maleate, ranitidine, cimetidine, and famotidine were 3, 5, 7, and 7.5 min, respectively. The detection limit for enalapril was 10 ng mL -1 and the calibration plot was linear in the range 2.5–50 µg mL -1. In-vitro interaction of enalapril with the commonly administered H 2 -receptor antagonists cimetidine, ranitidine, and famotidine in simulated gastric juice at different pH and 37°C was also studied by use of this method. These studies clearly indicated that most of these H 2 -receptor antagonists bind to enalapril causing drastic changes in the availability of the drug. The HPLC method is accurate, selective, sensitive, and reproducible.