2. Experimental
2.1. Instrumentation
All measurements were carried out with an AAS5 HydrEA atomic absorption spectrometer (Analytik Jena, Germany) equipped with a continuum source background correction system and an electrothermal atomizer with a transversely heated graphite tube. An HS 5 chemical vapor generation system (Analytik Jena) operated in the batch mode was coupled to the electrothermal atomizer via an MPE 5 furnace autosampler (Analytik Jena) for the introduction of the mercury vapor into the graphite tube. The vapor generated in the reactor was transported to the graphite tube through a polytetrafluorethylene (PTFE) transfer line (2.0 mm i.d. l = 0.5 m), connected to the autosampler, and a titanium capillary (1.0 mm i.d.) in the other extremity. The titanium capillary was introduced in the sampling hole of the graphite tube via the autosampler. In the case of mercury pre-concentration in the gold amalgamation system, the vapor generated in the reactor was transferred to the gold column of 7.4 cm long, i.d. 0.6 cm (Galab Technologies GmbH, Geesthacht, Germany) through a PTFE transfer line (2.0 mm i.d. l = 0.25 m), connected to the autosampler, and the titanium capillary in the other extremity through an identical PTFE transfer line, being the vapors additionally trapped in the graphite tube coated with gold as permanent modifier. A schematic diagram of the system is shown in Fig. 1.