9B-2 Spectrophotometers
Instruments for atomic absorption work are offered by numerous manufacturers; both single- and double-beam designs are available. The range of sophistication and cost (upward from a few thousand dollars) is substantial. In general, the instrument must be capable of providing a sufficiently narrow bandwidth to isolate the line chosen for the measurement from other lines that may interfere with or diminish the sensitivity of the
analysis. A glass filter suffices for some of the alkali metals, which have only a few widely spaced resonance lines in the visible region. An instrument equipped with readily interchangeable interference filters is available commercially. A separate filter and light source is used for each element. Satisfactory results for the analysis of 22 metals are claimed. Most instruments, however, incorporate good-quality ultraviolet/visible monochromators, many of which are capable of achieving a bandwidth
on the order of 1 A.