Orthogonal Hyphenation of Planar and Liquid Chromatography for Mass Spectrometry of Biomarkers out of the Bioassay Matrix (NP-HPTLC-UV/vis/FLD-Bioassay-RP/IEX-HPLC-UV/vis-ESI-MS).

Bioprofiling on the planar chromatogram with in situ biological/enzymatic assays is a powerful bioanalytical screening tool for the nontargeted detection of known and especially unknown/unidentified bioactive compounds directly in multicomponent mixtures (e.g., foods, spices, and botanicals). However, together with the bioactive zone, the adsorbed bioassay medium is eluted into the mass spectrometer (MS) and interfering with evaluation. Another sample track without bioassay has thus been handled in parallel. Hence, for a direct zone elution from the bioautogram, different setups were investigated to reduce the impact of the bioassay medium load. A biocompatible filter, orthogonal reversed-phase/cation-exchange columns (RP/IEX-HPLC), UV/vis detector, and a Rheodyne valve were installed between the zone eluting interface (after normal-phase high-performance thin-layer chromatography-multi-imaging-bioassay, NP-HPTLC-UV/vis/FLD-bioassay) and the MS. For the negative electrospray ionization mode (ESI), an RP-18e-HPLC column and valve switch were exploited. After gradient optimization, the RP-column retarded the eluted polar compounds and split-off the salts of the bioassay medium in the first minutes. This reduced the bioassay load and separated analyte signals thereof. However, most bioassay medium mass signals were predominantly detectable in ESI-MS. Here, the reduction of bioassay matrix signals was achieved by integrating a mixed-mode RP/IEX column. Finally, two different superhyphenations were successfully proven: NP-HPLC-UV/vis/FLD-bioassay-RP-HPLC-UV/vis-ESI-MS with a valve switch and NP-HPLC-UV/vis/FLD-bioassay-RP/IEX-HPLC-UV/vis-ESI-MS with or without it. Although the original bioprofiling (NP-HPTLC-UV/vis/FLD-bioassay) was prolonged from 3 to 13 min per sample, such superhyphenations covering chemistry/biology/mass spectrometry are considered as an efficient nontarget bioanalytical tool for fast evaluation of complex samples.