Lcq adv max ion trap mass spectrometer

Protected amino acids, rink amide resin, and other reagents for peptide synthesis, i.e., benzotriazol-l-yl-oxytripyrrolidinophosphonium hexafluorophosphate and O-benzotriazole-N,N,N’,N’-tetramethyluronium hexafluoro-phosphate, were purchased from Novabiochem (Merck KGAA, Darmstadt, Germany). All other chemicals were reagent grade from Sigma-Aldrich (Merck KGAA, Darmstadt, Germany). Peptide purifications were performed on a Jasco (JASCO International Co. Ltd., Hachioji, Tokyo, Japan) HPLC instrument equipped with two PU-1580 pumps and a MD-1510 diode array detector (working range: 195–659 nm), using a Phenomenex Jupiter 4U Proteo semi-preparative column (250×10 mm). Mass spectra were recorded using a Thermo-Finnigan (San Jose, CA, USA) LCQ ADV MAX ion-trap mass spectrometer, with an ESI ion source. UV–Vis spectra were recorded on an Agilent 8453 diode array spectrophotometer, equipped with a thermostated, magnetically stirred optical cell.

The HPLC-ESI-MS/MS analyses for photoproducts identification were performed by using a surveyor HPLC system (Thermo Finnigan, San Jose, CA, USA), equipped with a 150 × 2.0 mm, 4 µm Jupiter 4U Proteo column (Phenomenex). The mobile phase consisted of ultrapure water (0.1% v/v formic acid) (A) and ACN (0.1% v/v formic acid) (B). The starting concentration of eluent B was 2%, increased to 100% by 40 min with a linear gradient. This concentration was maintained for 5 min to wash the column. The flow rate was 0.2 mL min⁻¹. The MS/MS system consisted of an LCQ ADV MAX ion-trap mass spectrometer with an ESI ion source operating in ion-positive mode with the following instrument conditions: source voltage 5.0 kV; capillary voltage 46 V; capillary temperature 210 °C; tube lens voltage 55 V. The Xcalibur 2.0.7 SP1 software (Thermo Finnigan, San Jose, CA, USA) was used for spectra processing.