Analysis of phospholipid molecular species by liquid chromatography--atmospheric pressure chemical ionisation mass spectrometry of diacylglycerol nicotinates

Analysis and Identification of Golden pompano (Trachinotus blochii) Head Phospholipid Molecular Species by Liquid Chromatography-Mass Spectrometry

In this study, we first isolate phospholipid (PL) from Golden pompano head (GPH), and elucidate its structure. Gas chromatography (GC) was used to assess the GPH-PL fatty acid composition, Fourier transform infrared spectroscopy (FTIR) and ultraviolet absorption spectrometry (UV) were used for the qualitative analysis of GPH-PL, and LC-MS analysis was used to determine the major PL species. The results show that the contents of the various molecular species of GPH-PL were generally in the order phosphatidylcholine (PC) > sphingomyelin (SM) > lysophosphatidylcholine (LPC) > phosphatidylethanolamine (PE). The main molecular PC species are 16:0/18:2, 13:0/23:2, 27:2/9:0, 16:0/18:1, 12:0/22:2, 18:0/18:1, 18:0/24:1, and 18:1/24:0. The major SM species are 16:1/16:0, 16:0/18:1, 16:0/18:2, 16:0/26:2, and 18:1/24:1. The major LPC species are 18:1 and 16:0. The major PE species are 18:0/18:1 and 16:0/22:6. The total eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) contents in the GPH-PLs were 18.39%, and the content of DHA in the PL fraction was 16.47%. These results suggest that PLs from GPH is rich in polyunsaturated fatty acids (PUFA), which have good activity in anti-inflammation, anti-tumor, anti-osteoporosis and other aspects, and have important development prospects in the future.

Selective HPLC method development for soy phosphatidylcholine Fatty acids and its mass spectrometry

A novel, efficient and simple approach for soy phosphatidylcholine analysis according to its fatty acid composition was studied with reverse-phase high-performance liquid chromatography. The reverse-phase high-performance liquid chromatography analysis was performed isocratically using UV detector and simple mobile phase solvents consisting of isopropyl alcohol, methanol, and deionized water in the proportion of 70:8:22 v/v. The uniqueness of the proposed method was the separation of individual fatty acids of soy phosphatidylcholine. The high-performance liquid chromatography method for soy phosphatidylcholine was validated for linearity with correlation coefficient of above 0.99 for all the peaks separated according to their fatty acid composition. The intra-day and the inter-day precision studies provided the relative standard deviation of less than 2%. The limit of detection and limit of quantitation values were also calculated for all the resolved peaks of soy phosphatidylcholine. Also system performance parameters such as number of theoretical plates, capacity factor, tailing factor, separation factor, and peak resolution were studied systematically and found well within the acceptable range. The proposed high-performance liquid chromatography method was successfully applied to soy phosphatidylcholine extracted and purified from deoiled soy lecithin without any interference of impurities or solvent peaks. Individually, the collected peaks of sample soy phosphatidylcholine were subjected for mass spectroscopy. The mass spectra showed all the peaks having different saturated or unsaturated fatty acid chains attached to glyerophosphocholine moiety of soy phosphatidylcholine. The method developed is economic and well suited for estimation of soy phosphatidylcholine with its fatty acid composition.

Determination of phosphatidylethanolamine molecular species in various food matrices by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS2)

A liquid chromatographic-electrospray ionization-tandem mass spectrometric (LC-ESI-MS(2)) method has been developed for determination of the molecular species of phosphatidylethanolamine (PE) in four food matrices (soy, egg yolk, ox liver, and krill oil). The extraction and purification method consisted of a pressurized liquid extraction procedure for total lipid (TL) extraction, purification of phospholipids (PLs) by adsorption on a silica gel column, and separation of PL classes by semi-preparative normal-phase HPLC. Separation and identification of PE molecular species were performed by reversed-phase HPLC coupled with electrospray ionization tandem mass spectrometry (ESI-MS(2)). Methanol containing 5 mmol L(-1) ammonium formate was used as the mobile phase. A variety of PE molecular species were detected in the four food matrices. (C16:0-C18:2)PE, (C18:2-C18:2)PE, and (C16:0-C18:1)PE were the major PE molecular species in soy. Egg yolk PE contained (C16:0-C18:1)PE, (C18:0-C18:1)PE, (C18:0-C18:2)PE, and (C16:0-C18:2)PE as the major molecular species. Ox liver PE was rich in the species (C18:0-C18:1)PE, (C18:0-C20:4)PE, and (C18:0-C18:2)PE. Finally, krill oil which was particularly rich in (C16:0(alkyl)-C22:6(acyl))plasmanylethanolamine (PakE), (C16:0-C22:6)PE, and (C16:0-C20:5)PE, seemed to be an interesting potential source for supplementation of food with eicosapentaenoic acid and docosahexaenoic acid.

Investigation of natural phosphatidylcholine sources: separation and identification by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS2) of molecular species

This study is a contribution to the exploration of natural phospholipid (PL) sources rich in long-chain polyunsaturated fatty acids (LC-PUFAs) with nutritional interest. Phosphatidylcholines (PCs) were purified from total lipid extracts of different food matrices, and their molecular species were separated and identified by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS(2)). Fragmentation of lithiated adducts allowed for the identification of fatty acids linked to the glycerol backbone. Soy PC was particularly rich in species containing essential fatty acids, such as (18:2-18:2)PC (34.0%), (16:0-18:2)PC (20.8%), and (18:1-18:2)PC (16.3%). PC from animal sources (ox liver and egg yolk) contained major molecular species, such as (16:0-18:2)PC, (16:0-18:1)PC, (18:0-18:2)PC, or (18:0-18:1)PC. Finally, marine source (krill oil), which was particularly rich in (16:0-20:5)PC and (16:0-22:6)PC, appeared to be an interesting potential source for food supplementation with LC-PUFA-PLs, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

A review of chromatographic methods for the assessment of phospholipids in biological samples

Phospholipids are important constituents of all living cell membranes. Lipidomics is a rapidly growing field that provides insight as to how specific phospholipids play roles in normal physiological and disease states. There are many analytical methods available for the qualitative and quantitative determination of phospholipids. This review provides a summary of the methods that were historically used such as thin layer chromatography, gas chromatography and high-performance liquid chromatography. In addition, an introduction to applications of interfacing these traditional chromatographic techniques with mass spectrometry is provided.

Nanoflow liquid chromatography-tandem mass spectrometry for the characterization of intact phosphatidylcholines from soybean, bovine brain, and liver

Nanoflow liquid chromatography-electrospray ionization tandem-mass spectrometry (nanoLC-ESI-MS-MS) was applied for the characterization of intact phosphatidylcholine (PC) lipid molecules using a homemade reversed phase capillary column with a pulled tip for direct ESI at positive ion mode. Prior to the analytical column, a short capillary trapping column was utilized for on-line pre-concentration via microcross connection. Separation of intact phosphatidylcholines in the nanoflow LC column was carried out using a binary gradient elution method at 300 nL/min. The structures of the eluted PC components were determined by analysis of the typical fragment ions of PC molecules obtained from collision-induced dissociation (CID) after each precursor scan in mass spectrometry. In the current study, nanoflow LC-ESI-MS-MS analysis of PC molecules demonstrated the ability to obtain clear structural information, such as alkyl chain lengths and the degree of unsaturation with a protonated molecule ([M + H]+) and its characteristic fragment ions ([M + H-RCH2COOH]+, [M + H-RCH=C=O]+, and [M + H-184]+). Results from the nanoflow LC-ESI-MS experiment showed the limit of detection at 3.5 fmol for the 14:0/14:0-PC standard. This technique then was applied to intact PC extracts from soybean, bovine brain, and liver without derivatization and resulted in the identification of 28, 25, and 39 phosphatidylcholines, respectively. The LC-MS-MS method has been shown to be useful for the analysis of low concentration PC molecules in biological samples.

The bottom-up solution to the triacylglycerol lipidome using atmospheric pressure chemical ionization mass spectrometry

Presented here is an approach to representing the data from atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) of triacylglycerols (TAG) using a set of one, two, or three Critical Ratios. These Critical Ratios may be used directly to provide structural information concerning the regioisomeric composition of the triacylglycerols (TAG), and about the degree of unsaturation in the TAG. An AAA-type, or Type I, TAG has only one Critical Ratio, the ratio of the protonated molecule, [M + H]+, to the DAG fragment ion, [AA]+. The Critical Ratio for a Type I TAG is [MH]+/Z[DAG]+, and the mass spectrum of a Type I TAG can be reproduced from only this one ratio. An ABA/AAB/BAA, or Type II, TAG has two Critical Ratios, the [MH]+/sigma[DAG]+ ratio and the [AA]+/[AB]+ ratio. The [AA]+/[AB]+ ratio for a single TAG or TAG mixture can be compared with the [AA]+/[AB]+ ratios of pure regioisomeric standards, and the percentage of each regioisomer can be estimated. The abundance of the protonated molecule and the abundances of the two [DAG]+ fragment ions can be calculated from the two Critical Ratios for a Type II TAG. To calculate the abundances, the Critical Ratios are processed through the Bottom-Up Solution to the TAG lipidome. First, Critical Limits are calculated from the Critical Ratios, and then the Critical Ratios are classified into Cases by comparison with the Critical Limits. Once the Case classification is known, the equation for the abundance of each ion in the mass spectrum is given by the Bottom-Up Solution. A Type III TAG has three different FA and three Critical Ratios. The [MH]+/Z[DAG]+ ratio is the first Critical Ratio, the [AC]+/([AB]+ + [BC]+) ratio is the second Critical Ratio, and the [BC]+/[AB]+ ratio is the third Critical Ratio. The second critical ratio for a Type III TAG can be compared with regioisomeric standards to provide an estimate of the percentage composition of the regioisomers. The three Critical Ratios for a Type III TAG can be processed through the Bottom-Up Solution to calculate the four ion abundances that make up the APCI-MS mass spectrum. The Critical Ratios constitute a reduced data set that provides more information in fewer values than the raw abundances.

Recent advances in the application of mass spectrometry in food-related analysis

A review is presented on recent applications of mass spectrometry (MS)-based techniques for the analysis of compounds of food concern. Substances discussed are naturally occurring compounds in food products such as lipids, oligosaccharides, proteins, vitamins, flavonoids and related substances, phenolic compounds and aroma compounds. Among xenobiotics, applications of MS techniques for the analysis of pesticides, drug residues, toxins, amines and migrants from packaging are overviewed. Advances in the analysis of trace metals of nutritional and toxicological interest by MS with inductively coupled plasma (ICP) source are presented. The main features of mass spectrometry combined with separation instruments are discussed in food-related analysis. Examples of mass spectrometry and tandem MS (MS-MS) are provided. The development and application of matrix-assisted laser desorption ionization (MALDI) and electrospray (ESI) to the analysis of peptides and proteins in food is discussed. This survey will attempt to cover the state-of-the-art up from 1999 to 2001.