Coupling fluid mercury

The determination of trace metal impurities in pharmaceuticals requires a more sensitive methodology. Flame atomic absorption and emission spectroscopy have been the major tools used for this purpose. Metal contaminants such as Pb, Sb, Bi, Ag, Ba, Ni, and Sr have been identified and quantitated by these methods (59,66-68). Specific analysis is necessary for the detection of the presence of palladium in semisynthetic penicillins, where it is used as a catalyst (57), and for silicon in streptomycin (69). Furnace atomic absorption may find a significant role in the determination of known impurities, due to higher sensitivity (Table 2). Atomic absorption is used to detect quantities of known toxic substances in the blood, such as lead (70-72). If the exact impurities are not known, qualitative as well as quantitative analysis is required, and a general multielemental method such as ICP spectrometry with a rapid-scanning monochromator may be utilized. Inductively coupled plasma atomic emission spectroscopy may also be used in the analysis of biological fluids in order to detect contamination by environmental metals such as mercury (73), and to test serum and tissues for the presence of aluminum, lead, cadmium, nickel, and other trace metals (74-77). 

Earlier methods used to determine mercury in biological tissue and fluids were mainly colorimetric, using dithizone as the com-plexing agent. However, during the past two to three decades, AAS methods - predominantly the cold vapor principle with atomic absorption or atomic fluorescence detection - have become widely used due to their simplicity, sensitivity, and relatively low price. Neutron activation analysis (NAA), either in the instrumental or radiochemical mode, is still frequently used where nuclear reactors are available. Inductively coupled plasma mass spectrometry (ICP-MS) has become a valuable tool in mercury speciation. Gas and liquid chromatography, coupled with various detectors have also gained much importance for separa-tion/detection of mercury compounds (Table 17.1). 

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