In an inhalation study exposing mice, rats, and hamsters to ultrafine TiO2, the
particle burden in the lung was 1.6 mg TiO2/g of tissue immediately post exposure [27]. Thus, the currently demonstrated enzyme digestion and FFF detectionmethodology is applicable to nanoparticle toxicology studies that use superphysiological doses. However, improvement in the method sensitivity will be needed for use in toxicology studies that use environmentally relevant particle exposures.
The tissue processing protocol involves particle recovery by centrifugation and the
centrifugation process intrinsically allows a sample to be concentrated. Processing
larger initial tissue samples and recovering the particles in a small final volume is a straightforward way to achieve detection of low particle concentrations in tissue.