East West Analysis Graphite TubeIt is a consumable for graphite furnace atomic absorption, and the cost of using graphite furnace atomic absorption includes: element lamp, argon gas, electricity, graphite tube, graphite cone (ring), among which graphite tube consumables account for about 70% of the cost of graphite furnace atomic absorption. Therefore, the lifespan of graphite tubes directly affects the efficiency of graphite furnaces. The mechanism of graphite furnace atomization is the process of high temperature (up to 3000 degrees Celsius) atomization generated by high current through heating. At such high temperatures, both chemical and physical properties undergo significant changes, such as increased chemical reactivity, susceptibility to chemical reactions that are not easily occurring at room temperature, physical conductivity, thermal expansion, etc., which in turn affect the service life of graphite tubes.
The lifespan of graphite tubes directly affects the efficiency of graphite furnaces. Therefore, in daily use, attention should be paid to its related maintenance methods. Below are some simple rules summarized for everyone:
1. Start the pre designed air burning program for atomic absorption and perform air burning to make the absorption value of the graphite tube approximate a very small absorption value or zero.
2. When the graphite cone has been used, the contact area between the graphite cone and the graphite tube should be cleaned with a cotton swab squeezed with alcohol before installing it into the graphite furnace to calibrate the injection hole.
3. When using a graphite furnace to measure elements, the absorption value is measured in the form of peak area rather than peak height, which results in smaller errors. However, when using peak height measurement, there are too many influencing factors, which can lead to larger errors.
4. Adjust the depth of the automatic sampler capillary tube inserted into the graphite tube for analysis. Based on the fact that the lower end of the vacant droplet has just made contact with the inner wall of the graphite tube, and at the same time, the upper end of the droplet has also detached from the injection capillary.
5. The protective gas used for graphite furnaces should be high-purity (≥ 99.99%) inert gas argon instead of nitrogen. Due to nitrogen reducing the absorption values of most metal elements and causing severe molecular emission and background absorption with CN molecules that are naturally toxic to carbon at high temperatures. At the same time, the lifespan of graphite tubes is shorter than when using argon as a protective gas.
6. When testing a new batch of graphite tubes, it is necessary to first conduct selection tests on the drying temperature and time, ashing temperature and time, and atomization temperature and time of the element to be tested, in order to obtain the temperature and time of the element to be tested. Due to the varying resistance of each batch of graphite tubes.