At first, 800 μl of a 125 μg/ml BSA solutionwas filtered on “as grown” BDD-PM. The membranewas then rinsedwith 2ml ofwater, before elution of BSA with 1.6 ml of acetonitrile/water mixture (70/30). Around 1.4 ml of solution was finally collected. Then, the protein was digested in peptidic fragments using an endopeptidase, namely trypsin. The sample preparation protocol dedicated to mass spectrometry has been detailed previously [48]. We focused the MS analysis on two BSA typical specific peptides, HLVDEPQNLIK (P1) and LVNELTEFAK (P2). One can note that an internal standard is required for absolute quantification of analyte during LC tandemMS characterization, especiallywhen complex biologic media are involved. Here, the aim of the current study is solely to estimate the recovery of the diamond membrane, namely the ratio between the extracted to the applied analyte amounts. The chromatograms are illustrated in Fig. 5. The recovery ratios obtained with a pristine BDD-PM are 1.1% for P1 and 0.7% for P2, all ratios are shown in Table 2. Since a porous fiber membrane exhibits a higher porosity compared to a particle-loadedmembrane, its loading is rather lowcompared with usual cartridges. The same experiment, with identical solution was carried out on a diamond membrane functionalized with a C4 aliphatic chain thanks to the grafting technique detailed previously. After mass spectrometry analysis, the calculated ratio is 17.6% for P1 and 20.3% for P2. All further chromatograms and mass spectra are reported in the Supporting information. When compared with the “as grown” membranes (hydrogen terminated), the C4 modified membrane improves the protein extraction by a factor of 20. One can note that this effect is related to the increase of the retention factor ks (Eq. (1)) and therefore should be associated with the increase of the breakthrough volume. This experiment points out that the increase of the hydrophobic character of the membrane leads to an increase of the adsorption of a protein [49]. Compared to the usual silica solid phase, ‘as grown’ diamond can be used without functionalization as efficient reverse phase for protein extraction. A spontaneous, fast and one-step functionalization route increases recovery efficiency by a factor of 20.