Best-Matched Internal Standard Normalization in Liquid Chromatography–Mass Spectrometry Metabolomics Applied to Environmental Samples

2018 ◽  
Vol 90 (2) ◽  
pp. 1363-1369 ◽  
Author(s):  
Angela K. Boysen ◽  
Katherine R. Heal ◽  
Laura T. Carlson ◽  
Anitra E. Ingalls
Author(s):  
Narottam Pal ◽  
Avanapu Srinivasa Rao ◽  
Pigilli Ravikumar

<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>


2004 ◽  
Vol 50 (2) ◽  
pp. 365-372 ◽  
Author(s):  
Sally P Stabler ◽  
Robert H Allen

Abstract Background: We have developed an assay that uses stable-isotope-dilution liquid chromatography–mass spectrometry to assess S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) in body fluids to investigate the relationship of these metabolites to hyperhomocysteinemia. Methods: Commercially obtained SAM (D3 methyl) and 13C5-SAH uniformly labeled in the adenosyl moiety, which was synthesized using S-adenosylhomocysteine hydrolase, were added to samples followed by perchloric acid protein precipitation, C18 chromatography, and analysis by liquid chromatography–mass spectrometry with quantification by comparison of the areas of internal standard and endogenous peaks. Results: Estimates of intraassay imprecision (CV) were 5% and 17% for SAM and SAH, respectively (n = 10). SAM decreased and SAH increased in serum and plasma samples at both 4 °C and room temperature over 80 h. SAM and SAH were unstable in samples stored longer than 2 years at −20 °C. In 48 volunteers, the estimated reference intervals [from mean (2 SD) of log-transformed data] for serum SAM and SAH were 71–168 and 8–26 nmol/L, respectively. Fractional excretion of SAM was higher than that of SAH, and the urinary SAM:SAH ratio was much higher than the serum or erythrocyte SAM:SAH ratios. Conclusions: Stable-isotope-dilution liquid chromatography–mass spectrometry can be used to quantify SAM and SAH in biological fluids and tissues. Sample handling and storage must be stringently controlled for any epidemiologic or clinical use of such assays.


Author(s):  
NARMADA PALNATI ◽  
NALINI KOTAPATI ◽  
GOPAL VAIDYANATHAN

Objective: The objective of the study was to develop and validate a simple, accurate, and sensitive liquid chromatography–mass spectrometry (LC–MS)/MS method for the determination of lapatinib a dual tyrosine kinase inhibitor in rat plasma using gefitinib as internal standard. Methods: An Inertsil ODS column (50 mm×4.6 mm×5 μm) was used for separation with isocratic elution of 10 mM ammonium formate-acetonitrile (5:95 v/v). Analyte and internal standard were extracted from 50 μl of plasma using tertiary butyl methyl ether followed by subsequent reconstitution in a mixture of water-acetonitrile. Results: The extraction recoveries were 95% and 98% for lapatinib and gefitinib, respectively. The lower limit of quantification was 5 ng/ml with a precision of 6.2% and accuracy of 108%. The response was found to be linear over the range of 5–1000 ng/ml with a correlation coefficient of 0.999. The intraday and interday precision expressed as relative standard deviation was <15%. Conclusion: This validated method was applied to the pharmacokinetic study in Wistar rats. The proposed bioanalytical LC–MS/MS method for lapatinib is a simple, sensitive, and accurate to quantify the concentrations in rat plasma.


2019 ◽  
Vol 26 (2) ◽  
pp. 117-130 ◽  
Author(s):  
Tejas Wattamwar ◽  
Ashish Mungantiwar ◽  
Supriya Halde ◽  
Nancy Pandita

A rapid and sensitive liquid chromatography–mass spectrometry method was developed, optimized, and validated for simultaneous quantification of empagliflozin and metformin in human plasma using empagliflozin D4and metformin D6 as an internal standard. Analytes and internal standard were extracted from plasma by optimized solid-phase extraction technique using Strata X polymeric reverse phase (30 mg-1cc) solid-phase extraction cartridges. The prepared samples were chromatographed on Orosil C18 column (150 × 4.6 mm, 3 µ). Separation was done by pumping isocratic mobile phase consisting of methanol and 10 mM ammonium trifluoroacetate (90:10, v/v) in positive ion mode at a flow rate of 0.8 mL/min. The API 3200 liquid chromatography–mass spectrometry system having turbo ion spray as an ion source coupled with Shimadzu Prominence ultrafast liquid chromatography system was operated under the selected reaction monitoring mode. Turbo ion spray ionization was used for mass transition of m/z 468.070/355.100 and m/z 130.072/71.200 for empagliflozin and metformin, respectively. A method was successfully validated for concentration range of 10.09–5013.46 ng/mL for both the analytes and according to the United States Food and Drugs Administration guidelines. The linearity was found to be in the range of 10.09–403.46 ng/mL for empagliflozin and 25.44–5013.46 ng/mL for metformin. The limit of quantification was found to be 10.09 ng/mL for empagliflozin and 25.44 ng/mL for metformin. Intra- and inter-day/between batch precision determination for empagliflozin and metformin, expressed as coefficient of variation were within the acceptance limits and ranged below 13.16%. A short run time of 3.3 min allows analysis of more than 400 plasma samples per day. The developed method was successfully applied to fasting pharmacokinetic study in healthy human volunteers. Results of incurred sample re-analysis were within the acceptance range of ±20% of original value, for 97.2% of samples reanalyzed for empagliflozin and 100% of samples reanalyzed for metformin.


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