Analysis and Annotation of Phospholipids by Mass Spectrometry-Based Metabolomics.

Phospholipids are essential components of membrane lipid bilayers and serve as precursors of multiple signaling molecules, so alterations in their homeostasis are associated with the pathogenesis of numerous diseases. In this context, the application of mass spectrometry-based metabolomics has demonstrated great potential to comprehensively characterize the human phospholipidome. In this chapter, we describe an untargeted method for the determination of phospholipids and other related metabolites in a variety of biological matrices, including plasma/serum, erythrocytes, and tissues, based on the combination of high-throughput direct mass spectrometry fingerprinting and subsequent profiling by ultra-high-performance reversed-phase liquid chromatography coupled to mass spectrometry. Furthermore, we also review the characteristic fragmentation patterns of phospholipids with the aim of providing simple guidelines for their straightforward annotation.

Comprehensive and High-Throughput Method for Quantitative Fingerprinting of Phenolic Compounds.

Accurate, robust, and wide-coverage analytical tools are needed in polyphenol research to deal with the high physicochemical complexity of the secondary plant metabolome. In this chapter, a novel method based on reversed-phase ultrahigh-performance liquid chromatography coupled with a diode array detector and mass spectrometry is presented, which enables high-throughput, comprehensive, and quantitative fingerprinting of a broad spectrum of phenolic compounds and related metabolites in different food products. The simplicity, low-cost, and excellent analytical performance of this method would facilitate its implementation in food science for quality control and authenticity purposes.

High-Throughput Method for Wide-Coverage and Quantitative Phenolic Fingerprinting in Plant-Origin Foods and Urine Samples.

The use of mass spectrometry is currently widespread in polyphenol research because of its sensitivity and selectivity, but its usual high cost, reduced robustness, and nonavailability in many analytical laboratories considerably hinder its routine implementation. Herein, we describe the optimization and validation of a high-throughput, wide-coverage, and robust metabolomics method based on reversed-phase ultra-high-performance liquid chromatography with diode array detection for the identification and quantification of 69 phenolic compounds and related metabolites covering a broad chemical space of the characteristic secondary metabolome of plant foods. The method was satisfactorily validated following the Food and Drug Administration guidelines in terms of linearity (4-5 orders of magnitude), limits of quantification (0.007-3.6 mg L-1), matrix effect (60.5-124.4%), accuracy (63.4-126.7%), intraday precision (0.1-9.6%), interday precision (0.6-13.7%), specificity, and carryover. Then, it was successfully applied to characterize the phenolic fingerprints of diverse food products (i.e., olive oil, red wine, strawberry) and biological samples (i.e., urine), enabling not only the detection of many of the target compounds but also the semi-quantification of other phenolic metabolites tentatively identified based on their characteristic absorption spectra. Therefore, this method represents one step further toward time-efficient and low-cost polyphenol fingerprinting, with suitable applicability in the food industry to ensure food quality, safety, authenticity, and traceability.