Lipidomics allows researchers to probe changes in the lipidome as a result of disease, treatment, lifestyle, etc. Analysis of these lipids in a discovery mode is normally performed by a combination of liquid chromatography (LC) and accurate mass spectrometry (MS). Despite developments in analytical technology the detection and identification of lipids remains a significant challenge. Here we show the key benefits of a novel, benchtop MS and the features it provides to help overcome some of the drawbacks outlined for lipid analysis. Combining this novel MS data with third-party informatic solutions, demonstrates a powerful lipidomic workflow. The benefits of this approach are demonstrated using plasma samples from colon and rectum cancer and healthy control plasma.
Lipid extracts originating from the standard mixes was first assessed to establish instrument performance. Data were acquired using either data dependent (DDA) or data independent analysis (DIA). Resolution and mass accuracy were initially evaluated, providing 100,000 (FWHM) and 500ppb respectively for each lipid component. Based on previous literature, the most commonly identified lipids from human plasma (based on the NIST standard) highlighted the reduction in false positive identifications following database searching due to the high mass accuracy provided. A dynamic range of 5-orders was routinely demonstrated, whilst data acquisition rates of 100Hz were utilized for the MS methods, providing the ability to run with faster gradient profiles. Cancer-based study samples were prepared using the same protocol described for the lipid standards. Data processing via third-party informatics was used for peak picking, data normalization and lipid identification. Statistical analysis involving a range of MVA tools showed clear differentiation between the cancer types and healthy controls. Identification of the differential markers responsible for the group separation, was conducted using a lipid-specific database, highlighting phosphocholines, sphingomyelins and ceramides as the main lipid classes.