scholarly journals Calcineurin Activity Assay Measurement by Liquid Chromatography–Tandem Mass Spectrometry in the Multiple Reaction Monitoring Mode

2014 ◽  
Vol 60 (2) ◽  
pp. 353-360 ◽  
Author(s):  
Lynn Carr ◽  
Anne-Laure Gagez ◽  
Marie Essig ◽  
François-Ludovic Sauvage ◽  
Pierre Marquet ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Mononuclear Cells ◽  
Multiple Reaction Monitoring ◽  
Internal Standard ◽  
Reaction Monitoring ◽  
Activity Assay ◽  
Peripheral Blood Mononuclear ◽  
Blood Concentrations ◽  
Transplant Patients

Abstract BACKGROUND Blood concentrations of the calcineurin inhibitors (CNIs) cyclosporine and tacrolimus are currently measured to monitor immunosuppression in transplant patients. The measurement of calcineurin (CN) phosphatase activity has been proposed as a complementary pharmacodynamic approach. However, determining CN activity with current methods is not practical. We developed a new method amenable to routine use. METHODS Using liquid chromatography–multiple reaction monitoring mass spectrometry (LC-MRM-MS), we quantified CN activity by measuring the dephosphorylation of a synthetic phosphopeptide substrate. A stable isotope analog of the product peptide served as internal standard, and a novel inhibitor cocktail minimized dephosphorylation by other major serine/threonine phosphatases. The assay was used to determine CN activity in peripheral blood mononuclear cells (PBMCs) isolated from 20 CNI-treated kidney transplant patients and 9 healthy volunteers. RESULTS Linearity was observed from 0.16 to 2.5 μmol/L of product peptide, with accuracy in the 15% tolerance range. Intraassay and interassay recoveries were 100.6 (9.6) and 100 (7.5), respectively. Michaelis–Menten kinetics for purified CN were Km = 10.7 (1.6) μmol/L, Vmax = 2.8 (0.3) μmol/min · mg, and for Jurkat lysate, Km = 182.2 (118.0) μmol/L, Vmax = 0.013 (0.006) μmol/min · mg. PBMC CN activity was successfully measured in a single tube with an inhibitor cocktail. CONCLUSIONS Because LC-MRM-MS is commonly used in routine clinical dosage of drugs, this CN activity assay could be applied, with parallel blood drug concentration monitoring, to a large panel of patients to reevaluate the validity of PBMC CN activity monitoring.

scholarly journals Simultaneous Quantification of Apolipoprotein A-I and Apolipoprotein B by Liquid-Chromatography–Multiple- Reaction–Monitoring Mass Spectrometry

2010 ◽  
Vol 56 (12) ◽  
pp. 1804-1813 ◽  
Author(s):  
Sean A Agger ◽  
Luke C Marney ◽  
Andrew N Hoofnagle
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Human Plasma ◽  
Apolipoprotein B ◽  
Multiple Reaction Monitoring ◽  
Internal Standard ◽  
Reaction Monitoring ◽  
Normal Flow ◽  
Apolipoprotein A ◽  
Deming Regression

BACKGROUND If liquid-chromatography–multiple-reaction–monitoring mass spectrometry (LC-MRM/MS) could be used in the large-scale preclinical verification of putative biomarkers, it would obviate the need for the development of expensive immunoassays. In addition, the translation of novel biomarkers to clinical use would be accelerated if the assays used in preclinical studies were the same as those used in the clinical laboratory. To validate this approach, we developed a multiplexed assay for the quantification of 2 clinically well-known biomarkers in human plasma, apolipoprotein A-I and apolipoprotein B (apoA-I and apoB). METHODS We used PeptideAtlas to identify candidate peptides. Human samples were denatured with urea or trifluoroethanol, reduced and alkylated, and digested with trypsin. We compared reversed-phase chromatographic separation of peptides with normal flow and microflow, and we normalized endogenous peptide peak areas to internal standard peptides. We evaluated different methods of calibration and compared the final method with a nephelometric immunoassay. RESULTS We developed a final method using trifluoroethanol denaturation, 21-h digestion, normal flow chromatography-electrospray ionization, and calibration with a single normal human plasma sample. For samples injected in duplicate, the method had intraassay CVs <6% and interassay CVs <12% for both proteins, and compared well with immunoassay (n = 47; Deming regression, LC-MRM/MS = 1.17 × immunoassay − 36.6; Sx|y = 10.3 for apoA-I and LC-MRM/MS = 1.21 × immunoassay + 7.0; Sx|y = 7.9 for apoB). CONCLUSIONS Multiplexed quantification of proteins in human plasma/serum by LC-MRM/MS is possible and compares well with clinically useful immunoassays. The potential application of single-point calibration to large clinical studies could simplify efforts to reduce day-to-day digestion variability.

scholarly journals NEW METHOD DEVELOPMENT AND VALIDATION FOR THE DETERMINATION OF FEBUXOSTAT IN HUMAN PLASMA BY LIQUID CHROMATOGRAPHY–MASS SPECTROMETRY

2016 ◽  
Vol 8 (9) ◽  
pp. 61 ◽  
Author(s):  
Narottam Pal ◽  
Avanapu Srinivasa Rao ◽  
Pigilli Ravikumar
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Human Plasma ◽  
Method Development ◽  
Multiple Reaction Monitoring ◽  
Internal Standard ◽  
New Method ◽  
Liquid Chromatography Mass Spectrometry ◽  
Chromatography Mass Spectrometry

<p><strong>Objective</strong>:<strong> </strong>To develop a new method and validate the same for the determination of Febuxostat (FBS) in human plasma by liquid chromatography–mass spectrometry (LCMS).</p><p><strong>Methods</strong>:<strong> </strong>The present method utilized reversed-phase high-performance liquid chromatography with tandem mass spectroscopy. Febuxostat D9 (FBS D9) was used as internal standard (IS). The analyte and internal standard were separated from human plasma by using solid phase extraction method. Zorbax Eclipse XDB, C<sub>8</sub>, 100 mm x 4.6 mm, 3.5 µm column was used and HPLC grade acetonitrile, 5 millimolar (mM) ammonium format (80: 20, v/v) as mobile phase, detected by mass spectrometry operating in positive ion and multiple reaction monitoring modes.</p><p><strong>Results</strong>:<strong> </strong>The parent and production transitions for FBS and internal standard were at m/z 317.1→261.0 and 326.1→262.0 respectively. The method was validated for system suitability, specificity, carryover effect, linearity, precision, accuracy, matrix effect, sensitivity and stability. The linearity range was from 20.131 ng/ml to10015. 534 ng/ml with a correlation coefficient of 0.999. Precision results (%CV) across six quality control samples were within the limit. The percentage recovery of FBS and internal standard from matrix samples was found to be 76.57% and 75.03% respectively.</p><p><strong>Conclusion</strong>:<strong> </strong>Present study describes new LC-MS method for the quantification of FBS in a pharmaceutical formulation. According to validation results, it was found to be a simple, sensitive, accurate and precise method and also free from any kind of interference. Therefore the proposed analytical method can be used for routine analysis for the estimation of FBS in its formulation.</p>

scholarly journals A Hydrophilic Interaction Liquid Chromatography–Tandem Mass Spectrometry Quantitative Method for Determination of Baricitinib in Plasma, and Its Application in a Pharmacokinetic Study in Rats

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1600 ◽  
Author(s):  
Essam Ezzeldin ◽  
Muzaffar Iqbal ◽  
Yousif A. Asiri ◽  
Azza A Ali ◽  
Prawez Alam ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Multiple Reaction Monitoring ◽  
Internal Standard ◽  
Janus Kinase ◽  
Pharmacokinetic Studies ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass

Baricitinib, is a selective and reversible Janus kinase inhibitor, is commonly used to treat adult patients with moderately to severely active rheumatoid arthritis (RA). A fast, reproducible and sensitive method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the quantification of baricitinib in rat plasma has been developed. Irbersartan was used as the internal standard (IS). Baracitinib and IS were extracted from plasma by liquid–liquid extraction using a mixture of n-hexane and dichloromethane (1:1) as extracting agent. Chromatographic separation was performed using Acquity UPLC HILIC BEH 1.7 µm 2.1 × 50 mm column with the mobile phase consisting of 0.1% formic acid in acetonitrile and 20 mM ammonium acetate (pH 3) (97:3). The electrospray ionization in the positive-mode was used for sample ionization in the multiple reaction monitoring mode. Baricitinib and the IS were quantified using precursor-to-production transitions of m/z 372.15 > 251.24 and 429.69 > 207.35 for baricitinib and IS, respectively. The method was validated according to the recent FDA and EMA guidelines for bioanalytical method validation. The lower limit of quantification was 0.2 ng/mL, whereas the intra-day and inter-day accuracies of quality control (QCs) samples were ranged between 85.31% to 89.97% and 87.50% to 88.33%, respectively. Linearity, recovery, precision, and stability parameters were found to be within the acceptable range. The method was applied successfully applied in pilot pharmacokinetic studies.

scholarly journals Ultraperformance Liquid Chromatography–Tandem Mass Spectrometry Assay for Iohexol in Human Serum

2009 ◽  
Vol 55 (6) ◽  
pp. 1196-1202 ◽  
Author(s):  
Thomas M Annesley ◽  
Larry T Clayton
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Human Serum ◽  
Matrix Effects ◽  
Multiple Reaction Monitoring ◽  
Internal Standard ◽  
Structural Analog ◽  
Limit Of Quantification ◽  
Iodinated Contrast ◽  
Liquid Chromatography Tandem Mass

Abstract Background: Iohexol is an iodinated contrast dye that has been shown to be useful in the estimation of glomerular filtration rate (GFR) in patients with suspected renal insufficiency. We developed and validated an ultraperformance liquid chromatography (UPLC)–triple quadrupole mass spectrometry (MS/MS) assay for quantifying iohexol in human serum. Methods: Sample preparation involved dilution of 50 μL serum with 400 μL water, followed by protein precipitation with zinc sulfate and methanol containing the structural analog ioversol as the internal standard. After 1:20 dilution of the supernatant with water, 5 μL was injected into the UPLC-MS/MS system. Chromatography was performed using a Waters Oasis HLB 5-μm particle size, 2.1 × 20 mm column maintained at 50 °C. We used a 1-step acetonitrile/0.1% formic acid gradient to elute the compounds of interest at a common retention time of 0.96 min. The multiple reaction monitoring transitions used for integration and quantification were m/z 821.7→803.7 for iohexol and m/z 807.9→589.0 for ioversol in the electrospray positive ionization mode. Results: The assay was linear from 2.5 mg/L (lower limit of quantification) to 1500 mg/L iohexol, with a mean extraction efficiency of &gt;99%. Recovery of nominal target concentrations was 99%–102%. Interassay imprecision ranged from 7.9% at a concentration of 2.5 mg/L to 4.1% at 1000 mg/L. Ion suppression studies showed no matrix effects on the ionization of the 2 compounds. Conclusions: This rapid UPLC-MS/MS method can be successfully used for quantifying iohexol in human serum. .

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