scholarly journals DNA methylation determination by liquid chromatography-tandem mass spectrometry using novel biosynthetic [U-15N]deoxycytidine and [U-15N]methyldeoxycytidine internal standards

2008 ◽  
Vol 36 (18) ◽  
pp. e119-e119 ◽  
Author(s):  
E. P. Quinlivan ◽  
J. F. Gregory
Keyword(s):  
Mass Spectrometry ◽  
Dna Methylation ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Tandem Mass ◽  
Internal Standards ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass

scholarly journals Measurement of Urinary d- and l-2-Hydroxyglutarate Enantiomers by Stable-Isotope-Dilution Liquid Chromatography–Tandem Mass Spectrometry after Derivatization with Diacetyl-l-Tartaric Anhydride

2004 ◽  
Vol 50 (8) ◽  
pp. 1391-1395 ◽  
Author(s):  
Eduard A Struys ◽  
Erwin E W Jansen ◽  
Nanda M Verhoeven ◽  
Cornelis Jakobs
Keyword(s):  
Mass Spectrometry ◽  
Differential Diagnosis ◽  
Liquid Chromatography ◽  
Stable Isotope ◽  
Tandem Mass Spectrometry ◽  
Tandem Mass ◽  
Internal Standards ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass

Abstract Background: The differential diagnosis of d-2-hydroxyglutaric aciduria (d-2-HGA), l-2-hydroxyglutaric aciduria (l-2-HGA), and the combined d/l-2-hydroxyglutaric aciduria (d/l-2-HGA) can be accomplished only by the measurement of the corresponding 2-hydroxyglutarate (2-HG). Available methods for the determination of d- and l-2-HG in urine are either time-consuming and expensive or have not been extensively validated. We aimed to develop a method for their rapid and sensitive measurement. Methods: We used liquid chromatography–tandem mass spectrometry (LC-MS/MS) for the determination of d- and l-2-HG with stable-isotope-labeled internal standards. Urine samples of 20 μL were mixed with 250 μL of methanol containing the internal standards and subsequently dried under nitrogen. The analytes were derivatized by use of diacetyl-l-tartaric anhydride (DATAN) to obtain diastereomers, which were separated on an achiral C18 HPLC column and detected by MS/MS in multiple-reaction-monitoring mode. Results: The use of DATAN as chiral derivatization reagent provided very well separated peaks of the formed diastereomers of d- and l-2-HG, with a total runtime of 5 min. The inter- and intraassay CVs for d- and l-2-HG ranged from 3.4% to 6.2%. Mean recoveries of d- and l-2-HG, evaluated on two concentrations, were 94%. Detection limit of the presented method was 20 pmol for a sample volume of 20 μL. Method comparison of the LC-MS/MS method with a gas chromatography–mass spectrometry method, in which d- and l-2-HG were derivatized with R-(−)-butanol, showed good agreement between the two methods. Conclusions: Urinary d- and l-2-HG can be analyzed by MS/MS after derivatization with DATAN. The presented method may be suitable for the differential diagnosis of 2-HGA.

scholarly journals Quantitation and Validation of Fluoroquinolones in Eggs Using Liquid Chromatography/Tandem Mass Spectrometry

2007 ◽  
Vol 90 (2) ◽  
pp. 613-625 ◽  
Author(s):  
David A Durden ◽  
Tanya MacPherson
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Solid Phase ◽  
Tandem Mass ◽  
Internal Standards ◽  
Chromatography Tandem Mass Spectrometry ◽  
Fluoroquinolone Antibiotics ◽  
Liquid Chromatography Tandem Mass ◽  
Oasis Hlb

Abstract Fluoroquinolone antibiotics are labeled for very limited veterinary use for treatment of some animals and pets, but they are not authorized for food animals in Canada, including egg-producing birds. Because they are approved for other animals, however, fluoroquinolones may appear in eggs through off-labeling or accidental use. This method is capable of quantitating and confirming the presence of 4 fluoroquinolones, ciprofloxacin, danofloxacin, enrofloxacin, and sarafloxacin, over the concentration range 1 to 60 μg/kg (ppb) using 2 internal standards, norfloxacin or lomefloxacin. The compounds are extracted with acidic acetonitrile, isolated using Oasis HLB solid-phase extraction, and quantitated by liquid chromatography/tandem mass spectrometry at 2 transitions. The limits of detection (μg/kg) were evaluated from between-day experiments as: ciprofloxacin, 0.22; danofloxacin (m/z 314), 0.32; enrofloxacin, 0.22; and sarafloxacin, 0.31. The values for the decision limit, CC<sub/>, were 0.33, 0.36, 0.30, and 0.45 μg/kg, respectively.

scholarly journals High-Throughput Analysis of Sphingosine 1-Phosphate, Sphinganine 1-Phosphate, and Lysophosphatidic Acid in Plasma Samples by Liquid Chromatography–Tandem Mass Spectrometry

2009 ◽  
Vol 55 (6) ◽  
pp. 1218-1222 ◽  
Author(s):  
Max Scherer ◽  
Gerd Schmitz ◽  
Gerhard Liebisch
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Lysophosphatidic Acid ◽  
Tandem Mass ◽  
Internal Standards ◽  
Chromatography Tandem Mass Spectrometry ◽  
Butanol Extraction ◽  
Liquid Chromatography Tandem Mass ◽  
Sphingosine 1 Phosphate

Abstract Background: Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) are ubiquitous lipid messengers found in the blood and most cell types. Both lysophospholipids are ligands of G protein–coupled receptors and mediate important physiological processes. Moreover, lysophospholipids are potential biomarkers for various diseases, including atherosclerosis and cancer. Because existing methodologies are of limited value for systematic evaluations of S1P and LPA in clinical studies, we developed a fast and simple quantification method that uses liquid chromatography–tandem mass spectrometry (LC-MS/MS). Methods: Sphingoid base 1-phosphates and LPA species were quantified in negative-ion mode with fragments of m/z 79 and 153, respectively. The internal standards LPA 17:0 and [13C2D2]S1P were added before butanol extraction. Application of hydrophilic-interaction chromatography allowed coelution of analytes and internal standards with a short analysis time of 2.5 min. Results: Comparison of butanol extraction with a frequently used extraction method based on strong acidification of human plasma revealed artificial formation of LPA from lysophosphatidylcholine with the latter method. Validation according to US Food and Drug Administration guidelines showed an overall imprecision (CV) of <12% and a limit of detection <6 nmol/L for all lysophospholipid species. Concentrations of S1P and sphinganine 1-phosphate (SA1P) in EDTA-containing plasma were stable for 24 h at room temperature, whereas LPA concentrations increased substantially over this period. Conclusions: Our validated LC-MS/MS methodology for quantifying LPA, S1P, and SA1P features simple sample preparation and short analysis times, therefore providing a valuable tool for diagnostic evaluation of these lysophospholipids as biomarkers.

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