Stable Isotope Labelling and Tracing of Engineered Nanomaterials

Abstract

Nanomaterials that are synthesised from an enriched stable isotope are chemically and physically indistinguishable from the equivalent natural materials. They are, however, distinguished by a distinct non-natural isotope signature, which enables highly sensitive and selective tracing and quantification of the labelled material. This offers the opportunity of detecting trace quantities of isotopically labelled nanomaterials, from experiments carried out at low and environmentally relevant exposure levels, in complex natural samples with high and variable background levels of elements and particles. This chapter informs on the diverse applications of stable isotope labelled nanomaterials in exposure studies as well as key advantages and characteristics of the tracing approach. It also outlines key considerations relevant for the application of the technique. This includes (i) the selection of appropriate enriched isotopes; (ii) preparation of stable isotope labelled nanomaterials; (iii) analytical instrumentation and protocols required for tracing isotopically labelled materials in natural samples; and (iv) appropriate data reduction methods.