Targeted Metabolomic Profiling of Total Fatty Acids in Human Plasma by Liquid Chromatography-Tandem Mass Spectrometry.

Anas Al Aidaros,Majed Dasouki,Charu Sharma,Osama Y Al-Dirbashi,Georg F Hoffmann,Jürgen G Okun,Fatma Aljasmi,Claus-Dieter Langhans,Pranesh Chakraborty

doi:10.3390/metabo10100400

Abstract

This article reports a targeted metabolomic method for total plasma fatty acids (FAs) of clinical or nutritional relevance. Thirty-six saturated, unsaturated, or branched-chain FAs with a chain length of C8-C28 were quantified using reversed-phase liquid chromatography-tandem mass spectrometry. FAs in plasma (10 μL) were acid-hydrolyzed, extracted, and derivatized with DAABD-AE (4-[2-(N,N-Dimethylamino)ethylaminosulfonyl]-7-(2-aminoethylamino)-2,1,3-benzoxadiazole) at 60 °C for 1 h. Derivatization resulted in a staggering nine orders of magnitude higher sensitivity compared to underivatized analytes. FAs were measured by multiple-reaction monitoring using stable isotope internal standards. With physiological and pathological analyte levels in mind, linearity was established using spiked plasma. Intra-day (n = 15) and inter-day (n = 20) imprecisions expressed as variation coefficient were ≤10.2% with recovery ranging between 94.5–106.4%. Limits of detection and limit of quantitation ranged between 4.2–14.0 and 15.1–51.3 pmol per injection, respectively. Age-stratified reference intervals were established in four categories: <1 month, 1–12 month, 1–18 year, and >18 year. This method was assessed using samples from patients with disorders affecting FAs metabolism. For the first time, C28:0 and C28:0/C22:0 ratio were evaluated as novel disease biomarkers. This method can potentially be utilized in diagnosing patients with inborn errors of metabolism, chronic disease risk estimation, or nutritional applications.

Highlights

Fatty acids (FAs) are carboxyl group-containing compounds with a hydrocarbon chain of variable length and degree of unsaturation
Analysis of unaltered fatty acids (FAs) by liquid chromatography (LC)-MS/MS can be achieved in the negative ESI mode using anion transitions generated from the elimination of water or carbon dioxide
This study aims to develop a simple, sensitive, and selective LC-MS/MS method to routinely quantify a broad range of FAs in small plasma volume for clinical evaluations

Summary

Introduction

Fatty acids (FAs) are carboxyl group-containing compounds with a hydrocarbon chain of variable length and degree of unsaturation. In addition to their remarkable role as fuel molecules, FAs are indispensable constituents of simple and complex lipids, such as triglycerides, phospholipids, and glycolipids, and their biological activities encompass signaling pathways, gene expression, and regulation of membrane structure and functions These diverse functions substantiate the influence of proper FAs homeostasis on health, well-being, and risk of disease [1,2,3,4]. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) have been the primary analytical tools for FAs in all types of samples [13,14,15] Analysis using these methods requires significant sample preparation that involves derivatization to enhance volatility, thermal stability, and chromatographic separation. Applications of LC-MS/MS have expanded significantly in clinical laboratories in areas, such as therapeutic drug monitoring, drugs of abuse, clinical toxicology, and inborn errors of metabolism [18,19,20,21]

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