Autoflex 3 smartbeam maldi tof ms system

Trifluoroacetic acid, acetonitrile, and ethanol were purchased from Sigma-Aldrich (St. Louis, MO). An Autoflex III SmartBeam MALDI-TOF MS system, MTP Slide Adapter II, ImagePrep, conductive slides, sinapinic acid, and α-cyano-4-hydroxy cinnamic acid were purchased from Bruker Daltonics (Bremen, Germany). Optimum cutting temperature (OCT) compound was obtained from Leia (Leica Microsystems Nussloch GmbH, Germany). A peptide calibration standard was also obtained from Bruker Daltonics, which included angiotensin II, angiotensin I, substance P, bombesin, adrenocorticotrophic hormone clip 1–17, adrenocorticotrophic hormone clip 18–39, somatostatin 28, and rennin substrate. A Labconco Centrivap cold trap and concentrator was obtained from LabconcoCorp. (Kansas City, MO, USA). A Leica CM 1950 cryostat was purchased from Leica (Leica Biosystems Nussloch GmbH, Germany).

Samples of biosurfactant extracts (2 µL) were mixed 1: 1 with a α-cyano-4-hydroxycinnamic acid (CHCA) matrix at 3 μg/μL in ethanol: acetone (v/v). In order to study the effect of trifluoroacetic acid (TFA), in selected samples, 0.1% TFA was added to the CHCA matrix at a 1: 1 ratio (v/v). Biosurfactant extracts were then mixed with the matrix solution using a 1: 1 ratio (v/v). Once the samples had been prepared, they were spotted on a MTP AnchorChip™ MALDI target (Bruker Daltonik, Bremen, Germany) and allowed to air-dry. A calibration standard (Bruker Daltonik, Bremen, Germany) was used to perform external mass calibration. Mass spectra were obtained using an Autoflex III smartbeam MALDI-TOF-MS system (Bruker Daltonik, Bremen, Germany) as described in a previous study (Rincón-Fontán et al., 2017 (link)).