graphite petrolum coke
Nine points of use of longitudinal heating standard graphite petrolum coke
The life span of graphite petrolum coke directly affects the efficiency of graphite furnace. Therefore, in the daily use of the vertical heating standard graphite petrolum coke, pay attention to its related maintenance methods. Here are some simple rules for everyone:
1. The circulating water must have a pressure between 0.6-1.5Mpa.
2. When the graphite cone has been used, the contact point between the graphite cone and the graphite petrolum coke should be cleaned with a cotton swab squeezed into alcohol before loading into the longitudinal heating standard graphite petrolum coke, and then the graphite petrolum coke should be loaded into the graphite furnace , Calibrate the injection hole.
3. Start the pre-designed air-burning program of the atomic absorption graphite petrolum coke, and perform the air-burning of the graphite petrolum coke so that the absorption value of the graphite petrolum coke is close to a small absorption value or zero.
4. Adjust the depth of the autosampler capillary inserted into the longitudinal heating standard graphite petrolum coke. The lower end of the vacant droplet just touched the inner wall of the graphite petrolum coke, while the upper end of the droplet was also separated from the injection capillary.
5. The protective gas used for graphite furnaces should be high-purity (≥99.99%) inert gas argon instead of nitrogen. Because nitrogen reduces the absorption value of most metal elements, and the carbon of the standard graphite petrolum coke is heated longitudinally at high temperatures, the CN molecules are naturally toxic, resulting in severe molecular emission and background absorption. At the same time, the life of graphite petrolum coke is shorter than when argon is used as a shielding gas.
6. When changing a new batch of graphite petrolum coke to determine, you must first select the drying temperature and time, ashing temperature and time, and atomization temperature and time of the element to be tested to obtain the best temperature and time for the element to be tested. . Because the resistance of each batch of graphite petrolum coke will be different.
7. Please keep in mind the analyst: The sample solution to be tested must not contain strong oxidizing media such as perchloric acid and sulfuric acid, otherwise the graphite petrolum coke will be damaged quickly and severely. Especially with the operation of decomposing the sample and then rushing with perchloric acid, the perchloric acid must be cleaned up, otherwise it will appear that the starting standard curve is very good, and the absorption value will be very different when the sample solution is measured. The data cannot be used, and the data becomes bad when the standard solution is measured again.
8. When the graphite furnace is used to determine the element, the absorption value is measured in the form of peak area instead of the peak height, which brings a small error, and when the peak height is used for measurement, there are too many influencing factors, which will bring a larger error .
9. During the measurement, during the drying, ashing, and residue removal stages, the inner and outer gas circuits of the graphite petrolum coke must be protected by argon; the inner gas circuit is shut off during the atomization stage, and the heating time is generally 2-3 seconds; In the determination, the high-temperature atomization element adopts high-power heating, and the low-temperature atomization element adopts 1 second or 0.X second heating.