Instruments cold-vapor atomic fluorescence

EPA method 16. Iuses oxidation followed by a purge-and-lrap method and cold-vapor atomic fluorescence. Mercury is preconcentrated in the gold coated sand trap by amalgamation. One commercial instrument uses an atomic fluorescence deiection system and claims a working range from <0.05 ppl to - 250 ppb. Iliis method is quite useful for a variety of sample types ranging from seawater to sewage. 

A block diagram of a cold-vapor atomic fluorescence instrument for mercury determination is given in Figure IA2-1. Here, the predigested and oxidized sample is mixed with SnCb or another suitable reductant to generate elemental mercury. A gas-liquid separator is then used to separate the... 

Detection limits are presented for 61 elements by ten analytical determinative methods FAAS flame atomic absorption spectrometry ETAAS electrothermal atomization atomic absorption spectrometry HGAAS hydride generation atomic absorption spectrometry including CVAAS cold vapor atomic absorption spectrometry for Hg ICPAES(PN) inductively coupled plasma atomic emission spectrometry utilizing a pneumatic nebulizer ICPAES(USN) inductively coupled plasma atomic emission spectrometry utilizing an ultrasonic nebulizer ICPMS inductively coupled plasma mass spectrometry Voltammetry TXRF total reflection X-ray fluorescence spectrometry INAA instrumental activation neutron analysis RNAA radiochemical separation neutron activation analysis also defined in list of acronyms. 

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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