Separation of OXY and FLUO was effected with gradient elution (for details, see Table 1). UV-absorbance and fluorescence signals were recorded simultaneously for detecting OXY (λUV = 327 nm) and FLUO (λEX = 490 nm and λEM = 515 nm), respectively. Standard injections indicated retention times of 14.3 min (OXY) and 34.0 min (FLUO). Limits of detection were 12 μg/l (OXY) and 40 ng/l (FLUO).