HPLC-MS-MS-DAD Analysis of Purpurogallin Derivatives

HPLC-MS-MS-DAD analysis was run on an Agilent Q-TOF 6545 using an Agilent Poroshell 120 Phenylhexyl column (2.1mm diameter × 150 mm length, with 1.9 μm particle size) in eluent A consisting of 100% water with 20 mM formic acid and eluent B 100% acetonitrile with 20 mM formic acid, in a gradient running from 10% eluent B to 100% B in 10 min, held at 100% B at 2 min, back to 10% B over 0.1. min, and held at 10% B for 1.9 min. The column temperature was 40°C, and the eluent flow rate was 350 μl/min. The MS range measured was from 100 to 1700 Dalton, with a scan rate of 10 spectra/s, using positive and negative ionization separately. Fragmentation (for MS-MS) was done at 10, 20 and 40 eV [44 (link)]. The UV spectrum was compared to the published spectrum [14 (link)] and to a standard of purpurogallin (purpurogallin standard purchased from Sigma-Aldrich, as nr. P7380 MSDS), the latter having a slightly different UV spectrum (and retention time) than purpurogallin carboxylic acid. The UV spectra of purpurogallin carboxylic acid and purpurogallin carboxylic acid glycopyranoside were identical (Fig. S3).