When dichloromethane (CH2Cl2) is used in a liquid-liquid extraction from tissue homogenates, followed by evaporation and reconstitution (10-fold), HPLC-UV (238 nm) profiles show several peaks, one of which overlaps with my analyte. I believe it is not originated from tissues, but CH2Cl2 (probably stabilizers, impurities and/or degradation products).
I would appreciate if anybody give suggestions to solve this issue.
Thanks.

Repeat the extraction on water instead of tissue, observe results,
and/or
Use a different extracting solvent....

Thanks for a message.
Unfortunately, this happened even though water was used instead of tissue. Probably, it's time to switch the solvent, now.

I do not know of any stabilizers in CH2Cl2. If there are any questions, consider buying a higher quality solvent. However, I recommend to consider if this could be an extraction from a container, tubing, syringe etc. MeCl2 is known to extract plasticizers and stabilizers from plastic containers etc.

Thanks, Uwe.
I used glass apparatus throughout the procedure.
According to Fisher, CH2Cl2 contains amylene or cyclohexane as preservatives at < 100ppm. Because the samples were concentrated 10-fold, I've suspected these are from the preservatives.

If you have ever done GC/MS of methylene chloride you will fine that it certainly does have stabilizer, to retard HCl formation, as well as several related halogenated compounds at sufficient concentration to detect by LC. B&J brand uses cyclohexene or at least they did the last time I checked.

there is a simple procedure for removing stabilizer, but I can't remember it. It may be extract with sulfuric acid. You might simply distill to remove stabilizer as it has a higher boiling point. It concentrates when samples are concentrated by evaporation.

Did you also inject water directly, without the CH2Cl2 extraction?
The cleanup by shaking with con H2SO4, then H2O, then drying over Na2SO4 (slow to dry) should work (if you have amylene or cyclohexene, not cyclohexane), it does with chloroform.
(For those who want to do this cleanup with chloroform: years ago we had phosgene come at us after opening a bottle which stood for some weeks under an air atmosphere)