Maintenance of Graphite Furnace Atomization Atomic Absorption Spectroscopy Systems

KSS CLASS BY Dr. KVS MURTHY GARU

Maintenance of Graphite Furnace Atomization Atomic Absorption Spectroscopy Systems

Graphite Furnace assembly in sampling position

Graphite Furnace Atomization assembly is optionally available along with the flame version for analysis of trace metals on Atomic Absorption Spectroscopy systems. Graphite Furnace Atomic Absorption Spectroscopy highlights the features and benefits of this option. In order to get highest levels of reliability of results regular maintenance is an absolute must. An earlier article – Tips to ensure high uptime of your Atomic Absorption Spectrometer proposes some guidelines on maintenance of flame AAS systems.

Low-level trace metal determinations require use of graphite furnace atomization assembly. The present article makes some suggestions for maintenance of graphite furnace systems. The overall maintenance of graphite systems can be carried out routinely by you but for some tasks expert handling by service engineer of instrument supplier becomes necessary.

Routine Maintenance

Routine maintenance involves mostly visual observation which can be made easily before making use of the assembly. It can take at the most about 10 – 15 minutes but it is worth the time spent as you can rest assured on the reliability of reported results.

Graphite Tube

The graphite tube is the most critical component in the furnace assembly. Visually inspect daily for cracks, deformations, pitting or deposits around the injection hole. In case such damage is observed tube replacement is the best option.

Gas Supply

Ensure the supply of argon gas is adequate before utilizing the facility. The output supply pressure should be maintained between 50 – 60 psig.

Light Source

The hollow cathode lamp or electrodeless discharge lamp should have sufficient remaining life before it is put to use. After the lamp is switched on it should be given sufficient time to stabilize. Hollow cathode lamps can take half an hour to give a stable output and electrodeless discharge lamps can take longer stabilization time. Lamp energy status should be reviewed for stable output before the sample is introduced into the graphite tube.

Contact Rings

Like the graphite tubes the contact rings should also be inspected for damage due to pitting or cracks. It is time to replace the rings if any such damage is noticed.

Autosampler Tubing and Probe

The tubing should be inspected for any bends or kinks. The tube should be clean and if any blockages are observed or kinks develop the best solution is to replace the tubing. Similarly the probe should be cleaned or replaced if it gets blocked.

Expert Maintenance

Expert attention is required at least once or twice a year depending on usage and nature of samples analyzed. Such recommendations include:

• Cleaning of the mechanical assembly
• Cleaning of optical windows of any solid deposits
• Checking of sensitivity by means of calibration against traceable standards
• The cooling system should be inspected for blockages, if any, and the filters if found choked should be cleaned. If cleaning is not possible the filter should be replaced

Graphite furnace assembly is required for low level determinations in the ppb range of concentrations. At such levels reproducibility of results can be influenced by several factors depending on contamination from reagents, sampling and errors in analytical methods. However, preventive maintenance, as a bottom line, helps you ensure reliability of results over the useful lifespan of the facility.