1. Selective and accurate C5 acylcarnitine quantitation by UHPLC-MS/MS: Distinguishing true isovaleric acidemia from pivalate derived interference.
- Author
-
Minkler PE, Stoll MSK, Ingalls ST, and Hoppel CL
- Subjects
- Carnitine urine, Humans, Isovaleryl-CoA Dehydrogenase urine, Limit of Detection, Reproducibility of Results, Amino Acid Metabolism, Inborn Errors urine, Carnitine analogs & derivatives, Chromatography, High Pressure Liquid methods, Isovaleryl-CoA Dehydrogenase deficiency, Tandem Mass Spectrometry methods
- Abstract
Tandem MS acylcarnitine "profiles" are extremely valuable. Although used appropriately in newborn screening programs to identify patients with possible diseases, their inadequate quantitative accuracy and lack of selectivity is problematic for confirmatory testing. In this report, we show the application of our validated, selective, accurate, precise, and robust UHPLC-MS/MS method for quantitation of acylcarnitines, specifically to C5 acylcarnitines: pivaloyl-, 2-methylbutyryl-, isovaleryl-, and valerylcarnitine. Standardized calibrants were used to generate 13-point, 200-fold concentration range calibration curves. Samples were isolated by solid-phase extraction and derivatized with pentafluorophenacyl trifluoromethanesulfonate. Acylcarnitine pentafluorophenacyl esters were eluted in 14min chromatograms. Data demonstrating quantitative stability and method robustness over a five year time period are shown and these results validate the method's accuracy and robustness. Urine from patients with isovaleric acidemia (with the disease marker isovalerylcarnitine) and with pivaloylcarnitine present are shown. These results demonstrate the method's ability to distinguish true isovaleric acidemia from pivalate derived interference. Our method for acylcarnitine quantitation is shown to be accurate, precise, and robust for selective quantitation of isovalerylcarnitine, and thus is recommended for confirmatory testing of suspected isovaleric acidemia patients., (Copyright © 2017 Elsevier B.V. All rights reserved.) more...
- Published
- 2017
- Full Text
- View/download PDF