(i) "AAS is sensitive......." And in fact AAS is good at "ppm" levels, that's "parts per million", i.e. mg*L^-1.
(ii) "AAS is atom specific......." Given appropriate sample preparation, AAS may be made PARTICULAR to a particular element.
(iii) "AAS is fairly routine......." There are vast data on sample preparation and measurement. Given a required analysis it is fairly easy to develop an experimental protocol - and these are developed in house by the operator (as of course they should be).
Note that as in all analysis, a calibration curve is usually the first assignment. That is we analyze the response of known concentrations of analyte, and a calibration curve is constructed, which is linear to a first approx. The unknown sample is then matched to the curve.
