Graphitofenröhren

Graphitofenröhren are hollow cylinders made of high-purity graphite that serve as heating and reaction chambers in graphite furnace atomic absorption spectroscopy (GFAAS). They provide a chemically inert and thermally stable environment for the drying, ashing, and atomization of very small sample volumes, enabling trace-level elemental analysis.

Design and variants play a central role in performance. Typical graphite tubes are designed to withstand rapid temperature changes up to several thousand degrees Celsius while operating under inert or reducing atmospheres, usually with argon as the purge gas. They may be used as plain tubes or include an internal sample platform, which supports microdroplets of the liquid sample. Some configurations incorporate liners or coatings to reduce adsorption of matrix components and to improve repeatability. The tubes can vary in length, inner diameter, and wall thickness, and they are often paired with supporting components such as end plugs or shields.

Use in GFAAS involves placing the graphite tube inside the graphite furnace of the spectrometer. A controlled current heats the tube according to a programmed temperature profile that typically includes drying, ashing (decomposition of the matrix), and atomization of the analyte. The graphite tube’s properties promote rapid heating and efficient atomization of the analyte while minimizing chemical interferences. After measurements, residues may be removed through chemical cleaning or replacement of the tube.

Maintenance and lifespan depend on the sample matrix and operating conditions. Graphite tubes can incur wear from repeated high-temperature cycling and aggressive matrices, leading to contamination or physical degradation. They are typically replaced after a defined number of analyses or when signal quality declines. Applications span environmental, clinical, pharmaceutical, and food analysis for elements such as lead, cadmium, and arsenic at trace levels. Safety concerns center on high-temperature operation and handling of graphite components to prevent dust exposure.