How can a noisy baseline be resolved on a Lachat Flow Injection Analyzer?

Document ID

Document ID TE7977

Version

Version 4.0

Status

Status Published

Published Date

Published Date 05/21/2019
Question
How can a noisy baseline be resolved on a Lachat Flow Injection Analyzer?
Summary
Lachat noisy baseline
Answer
There are a number of things to consider if a noisy baseline is observed:

- Is the level of noise significant? When previewing the baseline, the noise can look worse than it really is if a peak has not been generated and the scale is still small. This is especially true when the baseline is very close to zero.
- Are the pump tubes or the pump tube cartridges worn? Pump tubes need to be changed regularly, while pump tube cartridges typically last a number of years. Also try reseating the pump tube cartridges in case one or more pump tubes did not seat well.
- Are there any clogs or crimps on the manifold? Check the flow of each reagent line. The lines can be placed in water for this. Lift each line out of the water one at a time and watch the flow of air to verify the flow is predominately forward.
- Check the waste line. Does it go into a container? If so, is the container on the floor, or below the level of the instrument? When a waste container is on the lab bench, you can see back pressure and surging as the flow goes through the waste line. Is the waste line submerged in the wastewater? This can also cause back pressure and can cause the baseline to drift. If the line goes into a sink, make sure the line is free flowing and not clogged up with old waste.
- Check the flow cell. Is there a bubble, fiber, or other foreign matter visible in the flow cell window? Tapping the flow cell can dislodge a bubble. Flushing with a syringe may help remove a fiber or other matter. Make sure the flow cell is clicked into place all the way down and not sticking up more than it's supposed to.


Also see
Are there any suggestions or tips on troubleshooting flow problems on the Lachat QC8500 FIA instruments?

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