Quantitative titanium imaging in fish tissues exposed to titanium dioxide nanoparticles by laser ablation-inductively coupled plasma-mass spectrometry.

Imaging studies by laser ablation-inductively coupled plasma mass spectrometry have been successfully developed to obtain qualitative and quantitative information on the presence/distribution of titanium (ionic titanium and/or titanium dioxide nanoparticles) in sea bream tissues (kidney, liver, and muscle) after exposure assays with 45-nm citrate-coated titanium dioxide nanoparticles. Laboratory-produced gelatine standards containing ionic titanium were used as a calibration strategy for obtaining laser ablation-based images using quantitative (titanium concentrations) data. The best calibration strategy consisted of using gelatine-based titanium standards (from 0.1 to 2.0 µg g-1) by placing 5.0-µL drops of the liquid gelatine standards onto microscope glass sample holders. After air drying at room temperature good homogeneity of the placed drops was obtained, which led to good repeatability of measurements (calibration slope of 4.21 × 104 ± 0.39 × 104, n = 3) and good linearity (coefficient of determination higher than 0.990). Under the optimised conditions, a limit of detection of 0.087 µg g-1 titanium was assessed. This strategy allowed to locate prominent areas of titanium in the tissues as well as to quantify the bioaccumulated titanium and a better understanding of titanium dioxide nanoparticle spatial distribution in sea bream tissues.