In　this　study,　an　in-tube　solid-phase　microextraction　column　packed　with　mesoporous　TiO2　nanoparticles,　coupled　with　MALDI-TOF-MS,　was　applied　to　the　selective　enrichment　and　detection　of　phosphopeptides　in　complex　biological　samples.　The　mesoporous　TiO2　nanoparticles　with　high　specific　surface　areas,　prepared　by　a　sol-gel　and　solvothermal　method,　were　injected　into　the　capillary　using　a　slurry　packing　method　with　in　situ　polymerized　monolithic　segments　as　frits.　Compared　with　the　traditional　solid-phase　extraction　method,　the　TiO2-packed　column　with　an　effective　length　of　1　cm　exhibited　excellent　selectivity　(alpha-casein/beta-casein/BSA　molar　ratio　of　1:1:100)　and　sensitivity　(10　fmol　of　a　beta-casein　enzymatic　hydrolysis　sample)　for　the　enrichment　of　phosphopeptides.　These　performance　characteristics　make　this　system　suitable　for　the　detection　of　phosphorylated　peptides　in　practical　biosamples,　such　as　nonfat　milk.