2478 dual absorbance detector

The purified organic extract (3 mg) was hydrolyzed in 1 mL 6 M HCl at 110 °C overnight in a sealed tube. The fatty acid residue was obtained by extracting the hydrolysate with 1 mL diethyl ether. Extraction was performed three times and the organic phase was rinsed twice with distilled water (2 mL). For ESI-MS analysis, the fatty acid residue was dissolved in methanol and mixed with 0.1 % formic acid, of which 20 μL was used in the LC/MSD-TOF system. The methanol-soluble residue was dried after repeated evaporation and re-dissolved in 20 mM HCl to a final concentration of 0.1 mM. The amino acids were then analyzed by HPLC, using the Waters AccQTag pre-column derivatization method (Cohen and Michaud 1993) . Reaction of amino acids with 6aminoquinolyl-N-hydroxysuccinimidyl carbamate yields derivatives that are detected at 254 nm. The analysis was performed on a Nova-Pak C18 column (3.9×150 mm) at a flow rate of 1 mL/min at 37 °C, attached to a Delta 600 chromatographic system with a 2478 Dual Absorbance detector and a 717plus Autosampler (Waters, Bedford, MA).

The crude lipopeptides (4 mg) was hydrolyzed in 1 ml 6 M HCl at 110 °C overnight in a sealed tube. The amino acids were then analyzed by HPLC, using the Waters AccQTag precolumn derivatization method [28] . Reaction of amino acids with 6-aminoquinolyl-Nhydroxysuccinimidyl carbamate reagent (AQC) yields derivatives that are detected at 254 nm.
The analysis was performed on a Nova-Pak C18 column (3.9×150 mm) at a flow rate of 1 ml/min at 37 °C, attached to a Delta 600 chromatographic system with a 2478 Dual Absorbance detector and a 717 plus Auto sampler (Waters, Bedford, MA).