Abstract Effective phosphoproteome of nanoscale sample analysis remains a daunting task, primarily due to significant sample loss associated with non-specific surface adsorption during enrichment of low stoichiometric phosphopeptide. We developed a novel tandem tip phosphoproteomics sample preparation method that is capable of sample cleanup and enrichment without additional sample transfer, and its integration with our recently developed SOP (Surfactant-assisted One-Pot sample preparation) and iBASIL (improved Boosting to Amplify Signal with Isobaric Labeling) approaches provides a streamlined workflow enabling sensitive, high-throughput nanoscale phosphoproteome measurements. This approach significantly reduces both sample loss and processing time, allowing the identification of &gt;3,000 (&gt;9,500) phosphopeptides from 1 (10) µg of cell lysate using the label-free method without a spectral library. It also enabled precise quantification of ∼600 phosphopeptides from 100 cells sorted by FACS (single-cell level input for the enriched phosphopeptides) and ∼700 phosphopeptides from human spleen tissue voxels with a spatial resolution of 200 µm (equivalent to ∼100 cells) in a high-throughput manner. The new workflow opens avenues for phosphoproteome profiling of mass-limited samples at the low nanogram level.

A streamlined tandem tip-based workflow for sensitive nanoscale phosphoproteomics