Lcms 2020 esi ms

Mass spectra of crude synthetic peptides and purified fractions were first obtained in a LCMS-2020 ESI-MS (Shimadzu Corp., Kyoto, Japan), loading 10 µL of 0.1 µg/µL peptide under positive ion mode at 4.5 kV and 350 °C for 15 min. Spectra were recorded and the resulting data analyzed using the Lab Solutions 5.42 SP3 software (Shimadzu Corp.). ESI-MS was performed for monitoring the correct synthesis by identifying various positive m/z ions corresponding to the product (z = +1, +2, +3, etc.).
Purified/enriched samples were later analyzed by MALDI-TOF MS loading 1 µL of 1 µg/µL peptide and 1 µL of the matrix (10 mg/mL of α-cyano-4-hydroxycinnamic acid in 50% acetonitrile with 0.1% formic acid in water) onto a micro scout sample plate (Bruker Daltonics Inc., Billerica, MA, USA) and measuring in MALDI-TOF-MS Microflex equipment (Bruker Daltonics Inc.) using flexControl 3.0 software (Bruker Daltonik GmbH, Bremen, Germany). Spectra were obtained in positive ion mode by reflection detection as additions of 10 rounds of 30 laser impacts each, at various points of the sample. Individual peaks collected by HPLC with a %area higher than 10% were also analyzed by MALDI-TOF-MS in order to monitor the peptide and its byproducts.

LCMS-2020 ESI-MS (Shimadzu Corp., Kyoto, Japan) equipment was used. 1 µg/µL stock sample solutions were prepared. 10 µL of stock sample solution was loaded and run in positive ion mode at 4.5 kV and 350 °C for 20 min. Data acquisition and analysis were performed using the Lab Solutions v5.42 SP3 software (Shimadzu Corp., Kyoto, Japan).