ASTM Drift and Noise Test Failed


I have been performing ASTM Drift and Noise Test on 1260 Infinity II DAD WR (G7115A) since yesterday, the results are the same - Noise failes at 254 nm (or so 0.03mah).

Module is new (less than 1 year).

In the last time I have performed  Qualification, I also had the problem, I changed the lamp and test passed, but with many afforts (maybe once per 10 times). On this time, there were drift issues too.

In addition, I do tests without flow cell.

Could you please advise what should I do.

  • Your last test results are not awfully bad. How does the intensity test look? Maybe the system just needs to be flushed/equilibrated a little longer?

    Did you pay attention to this section in the manual?

    ASTM drift tests require a temperature change below 2 °C/hour (3.6 °F/hour)
    over one hour period. Our published drift specification is based on these
    conditions. Larger ambient temperature changes will result in larger drift.
    Better drift performance depends on better control of the temperature
    fluctuations. To realize the highest performance, minimize the frequency and
    the amplitude of the temperature changes to below 1 °C/hour (1.8 °F/hour).
    Turbulences around one minute or less can be ignored.
    Performance tests should be done with a completely warmed up optical unit (>
    two hours). ASTM measurements require that the detector should be turned
    on at least 24 h before start of testing.

  • Thank you for your quick response.

    Why lack of flushing can cause a problem when there is no flow cell in the compartment?

    The last test is performed after 4 hours from starting. Then I done test after about 10 hours, but the problem was still alive.

  • The test can be done with or without flow cell. Like I said, the last test didn't look awfully bad to me (remember, a failed test in LabAdvisor doesn't necessarily indicate a real problem or even hardware failure).

    Check your environmental conditions, maybe there's a massive draft from the A/C, direct sunlight etc. An intensity test would be useful to get an idea about the detector performance in general. Make sure you use the correct lamp from Agilent and its screws are tight (but not "gorilla-ed" in).

    If the module is less than one year old, you still have warranty, so call your local Agilent office, if you need additional help.

  • Before your recommendations, I have turned on the module and warmed up lamps. Then I did test again for control and results are excellent without any involvement (0.01 mah). Maybe there were environmental issues as you said.

    I have one more question, I have heard about cleaning optical parts with alcohol (IPA) while having failure in tests. What parts should I clean and is it effective thing to do.

    Thank you in advance for your immediate and reasonable assistance.

  • Cleaning parts of the optic is a delicate issue. Most of them are non-accessible anyway. What can be cleaned are parts like the achromat lens. This can be done with a (good quality) cotton cloth or cotton swabs. However, this might only help removing dust, dirt or fingerprints. More likely optical parts degrade over time and become foggy/milky/cloudy. Here cleaning does not help at all. The degraded part needs to be replaced.

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