As far as I've experienced HPLC the following problems can occur to cause an unsteady baseline:

There is another thread dealing with that issue including also an article link dealing with this problem:

https://www.researchgate.net/post/Why_am_I_getting_Baseline_noise_in_HPLC

I hope this helps you somehow,

Best regards Ferenc

As far as I've experienced HPLC the following problems can occur to cause an unsteady baseline:

There is another thread dealing with that issue including also an article link dealing with this problem:

https://www.researchgate.net/post/Why_am_I_getting_Baseline_noise_in_HPLC

I hope this helps you somehow,

Best regards Ferenc

I agree with Ferenc's comments, major contributor would be the purity of your solvents and it would pay to re-assess you sample extraction/preparation protocol.It normally introduces impurities you pick out on your spectra.

"Achieving a flat baseline which does not exhibit spikes, ghost peaks, drift or wander in an unpredictable manner should be a primary goal when performing HPLC analysis or developing methods. Methods which result in flat baselines and have well defined, sharp peaks allow for accurate sample area integration. Integration algorithms perform poorly in quantifying peaks on sloped, drifting or noisy baselines. Excessive baseline noise contributes to many problems, including poor quantitation, high %RSD errors, peak identification errors, retention time variation and many other critical problems. Properly developed HPLC methods are reproducible methods which apply and utilize good chromatography fundamentals." WSL

For more detailed information on understanding the causes of and troubleshooting this problem, I would suggest reviewing this linked article, "Common Causes of Baseline Noise in HPLC, UHPLC"; https://hplctips.blogspot.com/2014/09/common-causes-of-baseline-noise.html

You can:

1. Use clean HPLC solvents only!

2. Premix your mobile phase manually.

3. Ultrafilter (0.1 or 0.22 um) your mobile phase before use.

4. Following the above any peaks you see are due to 'refractive index differences' or 'UV differences'. Therefore, do not operate near the UV cutoff of a solvent!

Thanks everyone for your guidance. The issue has been resolved to greater extent.

What did you do?

Proper filtration and sonication of mobile phase to reduce any possibility of mobile phase contamination. Meanwhile regular or irregular noise may result from air trapped in the system. The system was washed and the technician checked the instrument manually. The status of the detector was showing some error