In situ localization of tris(2,3-dibromopropyl) isocyanurate in mouse organs by MALDI-IMS with auxiliary matrix strategy

Abstract

Tris(2,3-dibromopropyl) isocyanurate (TBC) is one of the novel brominated flame retardants that has been widely used in consumer goods. Humans may be exposed to TBC daily. Studies showed that TBC can induce significant toxicity. However, there is currently no report on its in situ localization in organs. In this study, we aimed to develop a reliable and reproductive method to determine the in situ localization of TBC in mouse organs by matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS). As commercially available matrices were not able to detect TBC in tissue section, we then developed a novel MALDI-IMS method based on 1,5-diaminonaphthalene hydrochloride and silver trifluoromethanesulfonate (NDA/AgOTf) as the matrix for the in situ localization of TBC. AgOTf used as the auxiliary matrix in the negative-ion mode showed an excellent MS signal of TBC. The detection limit of [2AgOTf + Br]- was at the μg/mL level. The developed MALDI-IMS method was successfully employed to obtain the TBC spatial distribution in the mouse organs collected from mice exposed to 160 mg/kg/day of TBC for 30 days. High-pressure liquid chromatography-tandem mass spectroscopy (HPLC-MS/MS) was also used to evaluate the accumulation of TBC in liver, kidney, heart, and brain. The combination of MALDI-IMS and HPLC-MS/MS showed that TBC can accumulate in mice organs and it is mainly distributed in the renal parenchyma. In summary, an innovative method was developed for the analysis of TBC spatial distribution by MALDI-IMS using a novel NDA/AgOTf matrix, extending the application of MALDI-IMS in environmental pollutants.