A rapid HPLC method for determination of zolpidem and its degradation product in tablets using a monolithic column.
A simple, accurate reverse phase high-performance liquid chromatographic method, utilizing a monolithic silica column, for determination of zolpidem hemitartrate and its degradation product in tablet dosage form was developed. Analysis was achieved on the monolithic, C18 (100 mm, 3.9 mm) column, in isocratic mode with acetonitrile-NaH2PO4 (pH 7.0; 0.01 M; 35:65, v/v) as mobile phase and a flow rate of 2.5 mL/min at room temperature with UV detection at 245 nm. Diazepam was applied as an internal standard. The retention time of zolpidem and its degradation product was 2.14 and 1.89, respectively. Calibration curve was linear in the range of 0.12-5 µg/mL and the recovery values were found to be 97-101%. The limit of quantitation was determined 0.12 μg/mL. The relative standard deviation values of intraday and interday studies were calculated as 0.13-1.1% and 0.54-1.3%, respectively.
Determination of zolpidem in serum microsamples by high-performance liquid chromatography and its application to pharmacokinetics in rats.
A single-solvent extraction step high-performance liquid chromatographic method is described for quantitating zolpidem in rat serum microsamples (50 microl). The separation used a 2.1 mm I.D. reversed-phase OD-5-100 C18 column, 5 microm particle size with an isocratic mobile phase consisting of methanol-acetonitrile-26 mM sodium acetate buffer (adjusted to pH 2.0 with 40% phosphoric acid) containing 0.26 mM tetrabutylammonium phosphate (13:10:77, v/v/v). The detection limit was 3 ng/ml for zolpidem using an ultraviolet detector operated at 240 nm. The recovery was greater than 87% with analysis performed in 12 min. The method is simple, rapid, and applicable to pharmacokinetic studies of zolpidem after administering two intravenous bolus doses (1 and 4 mg/kg) in rats.
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LIST OF ILLUSTRATIONS ix ACKNOWLEDGMENTS xi INTRODUCTION: Goethe Coins a Phrase 1 PART ONE: CIRCULATION Chapter 1: Gilgamesh's Quest 39 Chapter 2: The Pope's Blowgun 78 Chapter 3: From the Old World to the Whole World 110 PART TWO: TRANSLATION Chapter 4: Love in the Necropolis 147 Chapter 5: The Afterlife of Mechthild von Magdeburg 170 Chapter 6: Kafka Comes Home 187 PART THREE: PRODUCTION Chapter 7: English in the World 209 Chapter 8: Rigoberta Menchu in Print 231 Chapter 9: The Poisoned Book 260 CONCLUSION: World Enough and Time 281 BIBLIOGRAPHY 305 INDEX 319