A flexible SALDI-MS substrate for no background interference detection

In this report, a flexible substrate was prepared for no background interference detection of small molecules with surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) via an electrospinning technique. The substrate is composed of polyamide (PA6)-carbon soot nanoparticles (CS NPs), in which CS NPs are evenly encapsulated in polyamide nanofibers. The encapsulation eliminates the interference of CS NPs during SALDI-MS detection. The prepared flexible substrate presents high sensitivity and good reproducibility and no interference in low mass range after hydrophobic treatment. With this substrate, small molecules can be successfully quantified with a limit of detection as low as 200 pmol. The detection results of the methadone in urine and the residual malachite green on fish skin demonstrate the promising applications of the substrate in analyzing real samples and directly sampling from irregular objects, which simplified sample pretreatment process.