简介:Although methods have been reported for the analysis of solids by atomic absorption
spectrophotometry, the technique generally is limited to metals in solution or solubilized through
some form of sample processing. Ref简介:Although methods have been reported for the analysis of solids by atomic absorption
spectrophotometry, the technique generally is limited to metals in solution or solubilized through
some form of sample processing. Refer to Chapter Three for a description of appropriate digestion
methods.
2.2 Preliminary treatment of wastes, both solid and aqueous, is always necessary because
of the complexity and variability of sample matrix. Solids, slurries, and suspended material must be
subjected to a solubilization process before analysis. This process may vary because of the metals
to be determined and the nature of the sample being analyzed. Solubilization and digestion
procedures are presented in Chapter Three.
2.3 When using the furnace technique in conjunction with an atomic absorption
spectrophotometer, a representative aliquot of a sample is placed in the graphite tube in the
furnace, evaporated to dryness, charred, and atomized. As a greater percentage of available
analyte atoms is vaporized and dissociated for absorption in the tube rather than the flame, the use
of smaller sample volumes or detection of lower concentrations of elements is possible. The
principle is essentially the same as with direct aspiration atomic absorption, except that a furnace,
rather than a flame, is used to atomize the sample. Radiation from a given excited element is
passed through the vapor containing ground-state atoms of that element. The intensity of the
transmitted radiation decreases in proportion to the amount of the ground-state element in the
vapor. The metal atoms to be measured are placed in the beam of radiation by increasing the
temperature of the furnace, thereby causing the injected specimen to be volatilized. A
monochromator isolates the characteristic radiation from the hollow cathode lamp or electrodeless
discharge lamp, and a photosensitive device measures the attenuated transmitted radiation.详细>