Classification of graphite powder and precautions for use
Graphite powder is the core of graphite furnace, and graphite powder plays a vital role in making a certain analysis reach the overall stability. In order to ensure that the analysis conditions remain stable across different atomization cycles or between different graphite powders, all graphite components—contact columns, graphite powders, and platforms—must be strictly controlled by the instrument manufacturer and graphite manufacturer. Graphite powder is mainly divided into the following categories:
Transverse heating of graphite powder, long-life tubes, etc. Now, let’s talk about the above-mentioned common characteristics of graphite powder in detail to discuss the selection of graphite powder for different applications in the analysis process:
High-density graphite powder: suitable for the determination of low atomization temperature and easy to form volatile oxides: Li, Na, K, Rb, Cs, Ag, Au, Be, Mg, Zn, Cd, Hg, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Se, Te and other elements. Application advantages: strong reducing atmosphere, not easy to generate volatile oxides, so the sensitivity is better than coating. Especially for: Ai, Si, Ge, Sn.
Pyrolytic coating tube: mainly for the determination of elements that easily form carbides: Ca, Cr, Cu, Ba, Sr, Ti, V, Ni, Pt, Rh, Pd, Pt, Ir, etc. Especially Ni, Cu, Ca , Ti, Sr and other elements are 10-30 times more sensitive than ordinary high-density graphite powder.
Platform graphite powder: It mainly relies on the radiant heating of graphite powder to optimize the atomization isothermal zone, which greatly improves the sensitivity and stability of the analysis.
Others include lateral heating graphite powder and long-life graphite powder. Among them, the long-life graphite powder can be much higher than ordinary graphite powder under higher temperature conditions (2800℃).
Use graphite powder to pay attention to these:
1. Choose the supporting horizontal heating platform according to the instrument model, and choose different tube types according to the test needs.
2. Before installation, confirm that the graphite powder is in good condition, such as whether the graphite cone is intact, the cleanliness of the graphite cone and the temperature sensor, etc., to ensure accurate measurement data and avoid affecting the service life of atomic absorption graphite.
3. When installing the horizontal heating platform, do not directly touch the atomic absorption graphite powder with your hands.
4. Before using the horizontal heating platform, carry out a pre-operation of the empty burning to make the empty burning value meet the requirements to ensure accurate measurement data.
5. Use appropriate gas and flow rate. Excessive reduction of operating costs will reduce the service life of the product and increase the possibility of product contamination.
6. Avoid overheating of pipe fittings, overheating will seriously reduce the service life of graphite powder
7. When the graphite powder is approaching its service life, please pay attention to timely replacement, otherwise it will increase the possibility of graphite cone damage and affect its service life and performance.