8 Diagnostic Testing and Troubleshooting
244 July 29, 2013, 715003794 Rev. B
2. Compare the current system operation with the way the system
operated before the problem arose. To identify normal operating
conditions, maintain a daily log noting overall system performance.
Specifically, measure the performance of individual instruments using
samples whose identity you know, preferably the ones used for
instrument acceptance.
3. Tracking system parameters and performance during normal operation
is a necessary precondition of effective troubleshooting. You must know,
for example, when system-tuning parameter values approximate those
specified at the time a test sample was previously run or that the lens
settings needed to achieve optimum sensitivity are higher than those
specified before. A need to specify extreme values to attain good results
implies that some part of the system requires attention.
When your system is installed, and each time you develop a new method,
fill out a checklist to record system conditions during normal operation.
Methodically investigate and eliminate possible causes of a problem to
identify the atypical system parameter. To do so, identify, in the order
listed below, the symptom that varies from normal system operation:
• System pressure (high, low, erratic)
• Baseline (flow-path-related or detector-electronics-related)
• Changes in peak retention time (incorrect or changing over time)
• Loss of peak resolution
• Abnormal peak shape (smaller than expected, broad, tailing, and so
on)
• Incorrect qualitative/quantitative results
4. Run performance tests for each chromatographic instrument to quickly
determine whether a problem exists with a particular instrument.
5. Consult the troubleshooting information contained in tables in this
chapter. The tables identify possible causes of a symptom and suggest
corrective actions. They are organized according to the parameters in
step 3, so you can narrow the possible causes of a symptom and find
suggested corrective actions. If you trace a problem to a system
instrument other than the separations module (for example the
detector), consult the operator’s guide for that instrument.
To Next Page
Loading...
