How to resolve the noise in Chromatography spectrum in L51 ?

[s544186414]

For the title:

I encountered some problem in experiment of USP Tadalafil for Enantiomer and Diastereomer purity.
In below control and condition:
Mode : LC
Detector : 222nm
Column : 4.6-mm X 25-cm; 10-micrometer packing L51
Flow rate : 0.75 mL/min
Injection volume : 10 micro-liter

In the spectrum of Sensitivity solution, I found a tiny peak at retention time of 4 min. Because of the concentration of this solution was too thin to pass the requirement of sensitivity. The signal-to-noise ration must be not more than 20.

Do you have any suggest for me to refer?
Thanks.

Regards

[dap]

Hello.
Was the system flushed with isopropanol after reverses phase chromatography before normal phase one? Try to mix mobile phase in single bottle, degas it via ultrasound, disable other pump channels.