Quantification of biotin in plasma samples by column switching liquid chromatography – tandem mass spectrometry

Author(s):  
Allan Weimann ◽  
Peter Plomgaard ◽  
Linda M. Hilsted ◽  
Henrik E. Poulsen ◽  
Emil L. Larsen
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Hytham Ahmed ◽  
Abdel-Aziz Wahbi ◽  
Hatem Elmongy ◽  
Ahmad Amini ◽  
Hirsh Koyi ◽  
...  

In the present work, the determination of omeprazole (OME) enantiomers in oral fluid and plasma samples was carried out utilizing microextraction by packed sorbent (MEPS) and liquid chromatography-tandem mass spectrometry. A chiral column with cellulose-SB phase was used for the first time for enantiomeric separation of OME with an isocratic elution system using 0.2% ammonium hydroxide in hexane-ethanol mixture (70 : 30, v/v) as the mobile phase. OME enantiomers were determined utilizing a triple quadrupole tandem mass spectrometer in positive ion mode (ESI+) monitoring mass transitions: m/z 346.3 ⟶ 198.0 for OME and m/z 369.98 ⟶ 252.0 for internal standard. The limits of detection and quantification of the present method for both enantiomers were 0.1 and 0.4 ng/mL, respectively. The method validation provided good accuracy and precision. The matrix effect factor was less than 5%, and no interfering peaks were observed. The interday precision values ranged from 2.2 to 7.5 (%RSD), and the accuracy of determinations varied from −9.9% to 8.3%. In addition, the pharmacokinetics (PK) of omeprazole enantiomers in healthy subjects after a single oral dose was investigated. (S)-Enantiomers showed higher levels than (R)-enantiomers throughout 24 h. It was found that the mean maximum concentrations of (R)- and (S)-omeprazole in plasma samples were about two times higher than in oral fluid.


2017 ◽  
Vol 12 ◽  
pp. 117739011772677 ◽  
Author(s):  
ASK Sankar ◽  
Shanmugasundaram Palani ◽  
Ravichandiran Velayudham

This research article presents the Quality by Design (QbD)–finalised conditions for a method that uses liquid chromatography-tandem mass spectrometry for the determination of concentration of enzalutamide (ENZ), an atypical anticancer drug, in a drug formulation and in spiked plasma samples. Critical process attributes (CPA) considered to be the influential parameters in separation, identification, and quantification processes by ultrahigh-performance liquid chromatography-electrospray ionisation-tandem mass spectrometry (UHPLC-ESI-MS/MS) were organic content, buffer strength, pH modifier, flow rate, spray voltage, sheath gas, and auxiliary gas that alter critical analytical attributes, such as retention time (R1) and area (R2). These factors were evaluated first in a factorial design (Taguchi orthogonal array design) and then extensively in a central composite design (CCD) to zero-in on the mobile phase for the quantification of ENZ standard drug and along with its internal standard (ENZIS) in spiked plasma samples and in formulation. Pareto chart from initial factorial design (Taguchi orthogonal array design) model suggested which of the CPA factors should be given the weightage, that is, to be exhaustively analysed in the CCD and response surface analysis. The elaborated parameters proposed by World Health Organization were studied by method validation, ie, selectivity, linearity, accuracy, precision repeatability system-suitability tests, method robustness/ruggedness, sensitivity, and stability. The strategy followed gives an insight on the development of a robust QbD-compliant quantitative UHPLC-ESI-MS/MS method for ENZ drug containing plasma samples (spiked).


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