Saxena et al. recently published a technique for
quantitative estimation of diesel and carbon black particles in lung cells basedon adapting the thermal-optical-transmittance analytical technique developed for
measuring organic and elemental carbon in air pollution samples [23]. This technique provides quantification of the low-volatility and non-volatile carbon by a precise instrumental analysis method, but again provides no information on the
primary particle size distribution or on the metal oxide components. In contrast,
SdFFF analysis of tissue provides quantitative information on the particle size
distribution after dispersal of the recovered particles by sonication in surfactant.
Our tissue processing method has the potential of offering high sensitivity since
the centrifugation steps allow concentrating the particles from large volume of
digested tissue into a small aliquot for analysis. Sequential collection of samples
during a SdFFF run is a well established technique [18]. The collected samples,
which represent concentrated and size-segregated fractions of the initial particles,
can be further analyzed, for example by transmission electron microscopy or elemental analysis. Compared to the other approaches cited above, the tissue digestion and SdFFF approach presented here provides the ability to analyze particle size distribution in large samples, such as a whole lung, and provides information on both carbonaceous and metal oxide particles. Carbonaceous combustion particles have lower density than the silicon dioxide used in this study, but analysis of carbon black by SdFFF has been demonstrated [24,25]. With additional method development this technique can become a useful tool for studying environmental particle burdens in lungs. Little is known about the background level of naturally formed nanoparticles, and this technique can also be applied to ecosystem studies of nanoparticles in sentinel and food chain organisms.