Fig. 2

a Standard additions data recorded for acetonitrile (AcN) or extract of C. ochrochlora (Matrix). MS/MS response at m/z 343.08 was tested in three-five replicates at every indicated concentration (error bars indicate SD for every measuring point). b Calibration curves made for extracts of C. ochlochlora (Y = 12,164 * X + 1.54e + 005 (with R2 = 0.9428)) and C. uncialis (Y = 12,761 * X + 1.21e + 006 (with R2 = 0.9197)) spiked with UA standards. Error bars indicate SD, calculated for every measuring point