Ltq xl instrument

To determine precisely the different iturin A homologs produced by B. amyloliquefaciens, the extracted iturin A samples were analyzed by LC–MS using Shimadzu HPLC system LC-10AVP equipped with a photo diode array (PDA) detector and a reversed-phase C-18 column, Luna^® (250 mm × 4.6 mm internal diameter, 5 μ particle size, Phenomenex, USA). The samples (50 μl) were injected and two different solvent systems were used for effective separation and detection of iturin A homologs. The mobile phase consisting of water (eluent A) and acetonitrile (eluent B) supplemented with 0.035% (v/v) formic acid was used at a gradient flow rate of 10 ml min⁻¹. The gradient conditions were as follows: firstly, starting at 90% eluent A and 10% eluent B, eluent A was linearly decreased to 55% with the increase of eluent B to 45% within the first 2.5 min; then, eluent A was linearly decreased to 0% with the increase of eluent B to 100% in the next 2.5 min and then maintained for 3 min; finally, eluent A was linearly increased to 90% with the decrease of eluent B to 10% in the next 1 min and then maintained for 1 min. The eluants were read at 220 nm using PDA detector (UVD340U, Dionex, USA). The LC-MS analyses were performed using an LTQ-XL instrument (Thermo Scientific, Germany) equipped with Xcalibur software.