a durable on - column tunneled frit was developed for use in nanoflow uplc systems . the frit was tunneled during sol - gel reaction . the tunneled - frit fabrication process is easy and reproducible in terms of back pressure and durability . this design creates low backpressure with high liquid flow , which is suitable for the nanoflowuplc application . a short packing tunneled - frit column was demonstrated to sustain 10 , 000 psi continuous liquid flow for over one week without any particle leakage or pressure instability . the tunneled - frit was also successfully applied to the fabrication of nanouplc trapping and analytical column system . it was demonstrated to have high separation efficiency and sensitivity for the analysis of tryptic peptides as well as improved detection sensitivity for phosphopeptide analysis .