A Comparison of Solid-Phase Extraction Techniques for Assay of Drugs in Aqueous and Human Plasma Samples

1984 ◽  
Vol 17 (16) ◽  
pp. 1811-1826 ◽  
Author(s):  
J. T. Stewart ◽  
T. S. Reeves ◽  
I. L. Honigberg
2019 ◽  
Vol 7 (11) ◽  
pp. 1757-1761 ◽  
Author(s):  
Dragica Zendelovska ◽  
Emilija Atanasovska ◽  
Kalina Gjorgjievska ◽  
Kristina Pavlovska ◽  
Krume Jakjovski ◽  
...  

BACKGROUND: A new simple, selective and accurate high-performance liquid chromatographic (HPLC) method utilising solid-phase extraction for the determination of pantoprazole in human plasma samples has been developed. AIM: The purpose of this paper was developing a new HPLC method suitable for the determination of pantoprazole in plasma samples, which enables simple and rapid isolation and concentration of the analysed drug.METHODS: The chromatographic separation was accomplished on a LiChroCart LiChrospher 60 RP select B column using a mobile phase composed of 0.2 % (V/V) water solution of triethylamine (pH 7) and acetonitrile (58:42, V/V) followed by UV detection was at 280 nm. The solid-phase extraction method using LiChrolut RP-18 (200 mg, 3 ml) was applied to the obtained good separation of investigated drug from endogenous plasma components. Best results were achieved when plasma samples were buffered with 0.1 mol/L KH2PO4 (pH 9) before extraction, eluted and reconstituted with acetonitrile and 0.001 mol/L NaOH after extraction, respectively. RESULTS: The standard calibration curves showed good linearity within the range of 25.0-4000.0 ng/mL with a correlation coefficient greater than 0.996. Retention times of pantoprazole and internal standard, lansoprazole was 4.1 and 6.0 min respectively. The limit of quantification was 25.0 ng/mL. For intra- and inter-day precision relative standard deviations ranged from 4.2 to 9.3%. The relative errors for stability investigations were ranged from 0.12 to -10.5%. CONCLUSION: This method has good precision and accuracy and was successfully applied to the pharmacokinetic and bioequivalence study of 40 mg pantoprazole in healthy volunteers.


2019 ◽  
Vol 15 (7) ◽  
pp. 776-784
Author(s):  
Xiaonian Han ◽  
Jing Wang ◽  
Jing Huang ◽  
Lirong Peng

Background: As first-line treatments for diabetes, sitagliptin and metformin have been widely prescribed as a combination to enhance the therapeutic effect. Objective: To establish a methodology to simultaneously monitor the two drugs in vivo by a reversedphase Liquid Chromatography-Tandem Mass Spectrometric (LC-MS/MS) method. Methods: The two drugs were extracted from 50 μl human plasma by ion-pair solid phase extraction. The separation of the plasma samples was implemented on an Agilent Zorbax SB-CN column (150×4.6 mm, 5.0 µm). The mobile phase was the mixture (80:20, v/v) of methanol and 5.0 mM ammonium formate in water (pH 4.5). An ion trap spectrometer equipped with an electrospray ionization source was utilized to detect the elution in positive mode. Quantification of the analytes was achieved by Multiple Reaction Monitoring (MRM) using the transitions of m/z 408.3→235.1 for sitagliptin and m/z 130.1→ 60.2 for metformin. Results: Sitagliptin and metformin demonstrated good linearity among the range of 1.00-1000 ng/mL and 5.00-4000 ng/mL. The intra-day and inter-day investigations displayed precisions of ≤ 3.6% and an accuracy range of -7.5% to 6.0% for the two drugs. The mean recovery of the two drugs was 96.0% and 98.5%. Under mandatory storage conditions, both the drugs gave an acceptable stability. The throughput of the assay was found to be more than 100 plasma samples per day ascribed to the run time of 3.0 min for each sample. Conclusion: The developed method was successfully applied to a pharmacokinetic study for a fixeddose tablet formulation containing 50 mg sitagliptin and 500 mg metformin in 12 healthy volunteers.


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