Graphite furnace technique autosampler

Tungsten-coil atomizers have to some extent been used in connection with atomic techniques in general and ETA-AAS in particular, and their popularity continues to rise. Their high simplicity and low cost make them attractive alternatives to graphite furnaces for many applications. However, they are much more interference-prone than their graphite counterparts. The interferences experienced by W-coil atomizers have been overcome in various ways, however. Thus, Barbosa et al. [25] avoid the interference from a salt matrix and implement a preconcentration step by electrochemically reducing Pb onto the coil surface. They use a flow injection system to deliver the sample through an anode inserted in the tip of the autosampler and the W-coil itself as cathode. The use of a W-coil as a platform inside a Massmann-type furnace provides no appreciable improvement over wall atomization [26]. 

Graphite furnace AAS generally offers highly sensitive detection for small sample amounts, however the sequential nature of the drying, ashing, and atomisation steps make it difficult to interface it to a continuous separation technique like HPLC. As a simple solution, the autosampler of a commercial GF-AAS instrament may be modified in such a way that the effluent is passed through a PTFE flowthrough cell from which the autosampler periodically injects a small aliquot (10—50 pL) into the furnace. Of course, this does not provide a continuous on-... 

A PE Model 5100 spectrophotometer, Zeeman HGA-600 graphite furnace atomizer and AS-60 HGA autosampler were used in the experimental validation of the AAS-HGA analytical technique. The spectrophotometer was equipped with a PE Series 7700 professional computer and Model PR-310 printer. A PE System 2 cadmium electrodeless discharge lamp, operated at the manufacturer s recommended current setting for modulated operation (170 mA), was used as the source lamp. Instrument parameters are listed in Attachment 2. 

Glassware is such a universal material used for sample preparation that it is very difficult to completely avoid it. However, serious consideration should be given to looking for alternative materials in as many of the ICP-MS sample preparation steps as possible. Today, the most common materials used to manufacture beakers, volumetric containers, and autosampler tubes for ultratrace elanent techniques such as graphite furnace atomic absorption (GFAA) and ICP-MS are mainly plastic based. Over the past 10-15 years, the demand for these kinds of materials has increased significantly becanse of the contamination issues associated with glassware. 

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