Identification of C5-Acylcarnitines Using Flow Injection Analysis-Tandem Mass Spectrometry

User Benefits

- C5-acylcarnitines (isovalerylcarnitine and pivaloylcarnitine) can be distinguished without special reagents or instruments by a few modifications of the analytical method in conventional flow injection analysis-tandem mass spectrometry.

Introduction

In newborn screening, amino acids and acylcarnitines in a dried blood spot (DBS) are analyzed by flow injection analysis-tandem mass spectrometry (FIA-TMS) to find amino acid, organic acid, and fatty acid metabolic disorders. FIA-TMS provides excellent throughput but is normally unable to distinguish isomers because a column is not used. For example, isovalerylcarnitine (i-C5), which is a marker metabolite of isovaleric acidemia (IVA), is isobaric with pivaloylcarnitine (p-C5), 2- methylbutyrylcartinine, and n-valerylcartinine. p-C5 can be present in a DBS due to newborn or maternal use of pivalate- containing antibiotics, but i-C5 and p-C5 cannot be distinguished by FIA-TMS. There are many reports of false positives derived from p-C5. An analytical method to distinguish i-C5 and p-C5 is needed to reduce false positives of IVA. This Application News describes a technique (patent pending) to distinguish i-C5 and p-C5 using a reference ion.

November 2, 2021 GMT