Utilization of solid-phase extraction and reversed-phase and ion-pair chromatography in the analysis of seven agrochemicals in water

1990 ◽  
Vol 38 (1) ◽  
pp. 142-144 ◽  
Author(s):  
Edward R. Bogus ◽  
Thomas L. Watschke ◽  
Ralph O. Mumma
Keyword(s):  
Solid Phase Extraction ◽  
Solid Phase ◽  
Reversed Phase ◽  
Ion Pair ◽  
Phase Extraction ◽  
Ion Pair Chromatography

A Rapid and Sensitive Method for the Pharmacokinetic Study of Janumet (Sitagliptin and Metformin) Tablets by LC-MS/MS Coupled with Ion-Pair Solid Phase Extraction

2019 ◽  
Vol 15 (7) ◽  
pp. 776-784
Author(s):  
Xiaonian Han ◽  
Jing Wang ◽  
Jing Huang ◽  
Lirong Peng
Keyword(s):  
Solid Phase Extraction ◽  
Pharmacokinetic Study ◽  
Solid Phase ◽  
Multiple Reaction Monitoring ◽  
Ion Pair ◽  
Phase Extraction ◽  
Plasma Samples ◽  
Ionization Source ◽  
Tandem Mass Spectrometric

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.

scholarly journals Determination of Antiviral Drugs and Their Metabolites Using Micro-Solid Phase Extraction and UHPLC-MS/MS in Reversed-Phase and Hydrophilic Interaction Chromatography Modes

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2123
Author(s):  
Luboš Fical ◽  
Maria Khalikova ◽  
Hana Kočová Vlčková ◽  
Ivona Lhotská ◽  
Zuzana Hadysová ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Solid Phase Extraction ◽  
Solid Phase ◽  
Gradient Elution ◽  
Reversed Phase ◽  
Tandem Mass ◽  
Phase Extraction ◽  
Hydrophilic Interaction

Two new ultra-high performance liquid chromatography (UHPLC) methods for analyzing 21 selected antivirals and their metabolites were optimized, including sample preparation step, LC separation conditions, and tandem mass spectrometry detection. Micro-solid phase extraction in pipette tips was used to extract antivirals from the biological material of Hanks balanced salt medium of pH 7.4 and 6.5. These media were used in experiments to evaluate the membrane transport of antiviral drugs. Challenging diversity of physicochemical properties was overcome using combined sorbent composed of C18 and ion exchange moiety, which finally allowed to cover the whole range of tested antivirals. For separation, reversed-phase (RP) chromatography and hydrophilic interaction liquid chromatography (HILIC), were optimized using extensive screening of stationary and mobile phase combinations. Optimized RP-UHPLC separation was carried out using BEH Shield RP18 stationary phase and gradient elution with 25 mmol/L formic acid in acetonitrile and in water. HILIC separation was accomplished with a Cortecs HILIC column and gradient elution with 25 mmol/L ammonium formate pH 3 and acetonitrile. Tandem mass spectrometry (MS/MS) conditions were optimized in both chromatographic modes, but obtained results revealed only a little difference in parameters of capillary voltage and cone voltage. While RP-UHPLC-MS/MS exhibited superior separation selectivity, HILIC-UHPLC-MS/MS has shown substantially higher sensitivity of two orders of magnitude for many compounds. Method validation results indicated that HILIC mode was more suitable for multianalyte methods. Despite better separation selectivity achieved in RP-UHPLC-MS/MS, the matrix effects were noticed while using both chromatographic modes leading to signal enhancement in RP and signal suppression in HILIC.

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