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Atomic fluorescence spectrophotometers (AFS) are widely used for trace element analysis of mercury, arsenic, selenium, and other elements in environmental, food, pharmaceutical, and geological samples. Due to the complexity of the optical system, gas system, atomization system, and detection components, various operational failures may occur during long-term use. The following seven common problems are frequently encountered during instrument maintenance and troubleshooting.
One of the most common AFS failures is a weak or completely absent fluorescence signal. The main causes include insufficient lamp intensity, incorrect lamp position, aging hollow cathode lamps, or poor atomization efficiency.
Operators should first check whether the lamp is operating normally and whether the lamp current and alignment parameters meet requirements. If the lamp has been used for a long period, replacement may be necessary. In addition, problems with the atomizer, such as insufficient hydrogen supply or poor sample introduction, can also reduce fluorescence intensity.
Signal instability is often related to fluctuations in gas flow, irregular sample introduction, or contamination in the atomization system. Unstable carrier gas or shielding gas pressure may cause variations in atomization efficiency.
Regular inspection of gas regulators, pipelines, and flow controllers is essential. The injection system should also be cleaned periodically to remove salt deposits and sample residues that may affect atomization performance.
Excessive background noise can seriously affect detection limits and quantitative accuracy. Common causes include contaminated reagents, impure carrier gases, dirty optical components, and electromagnetic interference.
Using high-purity reagents, maintaining clean laboratory conditions, and replacing gas purification filters regularly can significantly reduce background interference. Optical windows and detector areas should also be checked for dust or contamination.
When repeated measurements show large differences, the problem may come from inconsistent sample preparation, unstable chemical reactions, or improper instrument parameters.
For hydride generation atomic fluorescence systems, the concentration and stability of reducing agents, such as sodium borohydride, directly influence signal repeatability. Fresh preparation of reagents and accurate control of reaction conditions are important for reliable results.
The gas system is a critical part of atomic fluorescence instruments. Leakage in tubing, connectors, or valves can cause unstable flames, reduced sensitivity, or instrument alarms.
Routine leak testing should be performed, especially after replacing gas lines or maintenance components. Maintaining correct gas pressure and flow rates ensures stable atomization and protects the instrument from abnormal operation.
Autosampler failures can interrupt continuous analysis. Common symptoms include inaccurate sample positioning, failure to aspirate samples, or inconsistent injection volumes.
Possible causes include blocked sampling needles, damaged tubing, air bubbles, or incorrect software settings. Cleaning the sampling system and checking mechanical movement can usually resolve these issues.
Modern atomic fluorescence spectrophotometers rely heavily on computer control systems. Communication failures between the instrument and software may occur due to damaged cables, incorrect drivers, or software configuration problems.
Restarting the system, checking communication ports, updating software, and verifying instrument settings are common solutions. Regular data backup and software maintenance also help prevent unexpected failures.
Atomic fluorescence spectrophotometers require careful operation and preventive maintenance to maintain high sensitivity and accuracy. Problems such as weak signals, unstable fluorescence, high background noise, poor repeatability, gas leakage, autosampler faults, and software errors are among the most common challenges faced by laboratories. By establishing regular inspection procedures and addressing problems at an early stage, users can improve instrument reliability, extend service life, and ensure high-quality analytical results.