dye tracing
...that modern dye tracing techniques are capable of detecting concentrations of dye as low as one part per trillion?
...that modern <b id="mwCw4"><a href="./Dye_tracing" id="mwCw8" rel="mw:WikiLink" title="Dye tracing">dye tracing</a></b> techniques are capable of detecting concentrations of <a href="./Dye" id="mwCxA" rel="mw:WikiLink" title="Dye">dye</a> as low as one <a href="./Parts-per_notation" id="mwCxE" rel="mw:WikiLink" title="Parts-per notation">part per trillion</a>?