Recently, I have been cooperating with the VERA laboratory on dedecting minute amounts of Chlorine in steel [bibcite key=Winkler2015]. Usually, the detection of Cl is easily done by regular Neutron Activation Analysis (see e.g. [bibcite key=Steinhauser2006c,Steinhauser2006b]), in this case the very small amount of chlorine in combination with the interference from the matrix (Fe) made it necessary to find new ways of detection.
What we came up with is the idea [bibcite key=Winkler2015] of using the long-lived isotope 36Cl that can be created by neutron capture from the stable 35Cl and measure it after dissolution of the samples by AMS.
For all the dirty details, check out the article!