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Rationale: Due to the dynamic nature of phosphorylation states and the low stoichiometry of phosphopeptides, it is still a challenge to efficiently capture phosphopeptides from complex biological samples before mass spectrometry analysis. Among the enrichment strategies, metal oxide affinity chromatography (MOAC) is one of the most widely used and the one with the most potential. It is based on reversible Lewis acid–base interactions between the metal oxides and the negatively charged phosphate groups to achieve the specific selection of phosphopeptides. Methods: A novel MOAC affinity probe, denoted as G@PDA@ZrO2, was successfully synthesized by in situ grafting ZrO2 onto the surface of graphene (G) modified with polydopamine (PDA). The novel MOAC probe thus obtained was used for phosphopeptide enrichment. Results: This novel MOAC affinity probe when used to selectively enrich phosphopeptides from standard protein digest solutions exhibited a high selectivity (β‐casein:bovine serum albumin = 1:1000), a low detection limit (4 fmol), and a high loading capacity (400 mg/g). At the same time, the experimental results proved that G@PDA@ZrO2 had great recyclability (five cycles), stability, and reproducibility. Subsequently, G@PDA@ZrO2 was applied to enrich phosphopeptides from human saliva and human serum, in which 25 and 4 phosphopeptide peaks, respectively, were detected. Conclusions: This novel MOAC affinity probe (G@PDA@ZrO2) showed good performance in enriching phosphopeptides. Thus, G@PDA@ZrO2 has good potential in phosphopeptidomics analysis. [ABSTRACT FROM AUTHOR]

• MM-IMAC was synthesized with Ti4+ incorporated. • Phospholipids in krill were extracted by coordination with the phosphate group. • The extract was lipidomics analyzed by HILIC-MS under optimized conditions. • MM-Ti4+-IMAC-HILIC-MS was reliable and efficient for the lipidomics study of food matrix. Phospholipids enriched krill is a functional food beneficial in cardiovascular diseases. Herein, monodisperse microsphere-based immobilized metal affinity chromatographic material (MM-IMAC) was synthesized with Ti4+ incorporated to enrich phospholipids from krill by coordination with phosphate group. The extract was profiled by hydrophilic interaction chromatography-mass spectrometry (HILIC-MS) with 154 phospholipid molecular species detected. The parameters were loading solvent n -hexane/isopropanol (2:8, v/v), flow rate 0.8 mL·min−1, and eluting volume 1 mL. Besides, eicosapentaenoic and docosahexaenoic acids structured phospholipids were located, such as phosphatidylcholine (PC) 20:5/22:6, phosphatidylinositol (PI) 18:0/20:5, etc. Finally, this method was validated in linearity (R2 ≥ 0.9953), sensitivity (LOD ≤ 0.53 μg·mL−1 and LOQ ≤ 1.66 μg·mL−1), precision (RSD intraday ≤ 4.86% and RSD interday ≤ 6.25%), and recovery (58–83%). It indicated that the MM-Ti4+-IMAC-HILIC-MS was reliable and efficient in specific study of phospholipids in food matrix. [ABSTRACT FROM AUTHOR]