TABLE OF CONTENTS Different techniques have evolved for trace metal analysis of polymers. Generally speaking, the techniques come under two broad headings:
Destructive techniques: these are techniques in which the sample is decomposed by a reagent and then the concentration of the element in the aqueous extract determined by a physical technique such as atomic absorption spectrometry (AAS; Section 1.1.1), graphite furnace atomic absorption spectrometry (GFAAS; Section 1.1.2), cold vapour atomic absorption spectrometry (CVAAS; Section 1.1.4), Zeeman atomic absorption spectrometry (ZAAS; Section 1.1.5), inductively coupled plasma atomic emission spectrometry (ICP-AES; Sections 1.1.6 and 1.1.8), visible spectrometry (Section 1.1.13), and polarographic or anodic scanning voltammetric techniques (Section 1.114).
Non-destructive techniques: these include techniques such as X-ray fluorescence (XRF; Section 1.2.1) and neutron activation analysis (NAA; Section 1.2.2.), in which the sample is not destroyed during analysis.
Since shortly after its inception in 1955, AAS has been the standard tool employed by analysts for the determination of trace levels of metals. In this technique a fine spray of the analyte is passed into a suitable flame, frequently oxygen acetylene or nitrous oxide acetylene, which converts the elements to an atomic vapour. Through this vapour is passed radiation at the right wavelength to excite the ground state atoms to the first excited electronic level. The amount of radiation absorbed can then be measured and directly related to the atom concentration: a hollow cathode lamp is used to emit light with the characteristic narrow line spectrum of...
