Holmium modified TiO2 nanocomposites as a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry matrix for the detection of bisphenol S and indigo

Holmium (Ho) modified TiO2 (Ho–TiO2) nanocomposites have been prepared by a sol–gel process, and were used as an effective adsorbent and matrix for the enrichment and analysis of bisphenol S and Indigo by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The low detection limits of bisphenol S (BPS) and Indigo (ID) are 0.1 pg·mL−1 and 5 pg·mL−1, respectively. Extremely BPS detection could be achieved in tea samples with good recovery (81.5–93.0%).