This may not be helpful, but I use phosphomolybdic acid stains to detect fats and long-chain isoprenoid alcohols. If you are strictly detecting something like a phenolic, which has more specific staining, you could do a first-pass with an Fe3+ stain or other somewhat selective stain, and then do a second pass for contamination with phosphomolybdic acid, which will show spots for your phenolic AND the contaminant. Once you get out of benzene rings though, this becomes harder. Maybe someone else has a good idea for those compounds?

@Francis: Thanks for your answer. I read somewhere that you could use p-anisaldehyde stain, though I haven't tried it. I will try out your idea and get back to you. Cheers!

if you spray with 15% H2SO4 with heating it shows pale brown spots

There are no sprays / dips 'specific' for plasticisers.

We find a lot of the phthalates in question come from low grade plastic containers used to store samples. This is readily avoided by using higher quality food grade plastic. Another common source in our labs is from petroleum ether and ethyl acetate. As such these solvents are always distilled prior to use. After taking these precautions we do not have issues with phthalates.

Thanks for your answers.

I would like to suggest an UV absorption detection of the phthalate on TLC. It can be done with F254 Si under short wavelength lamp in a dark box.

It gives faint brown spots after spraying with H2SO4. followed by heating on TLC this in case of dioctyl phathalte ester ( tried before)

by the way there is natural phthalte ester reported from Asefotedia family Apiaceae

Please check on this link; Full text of "IDENTIFICATION OF PLASTICIZERS IN PLASTICS BY THIN-LAYER CHROMATOGRAPHY" http://archive.org/stream/nasa_techdoc_19720006940/19720006940_djvu.txt

I agree  with Russell . This is usually an uncommon problem , which may be from the usuage of low quality   plastic containers and from solvents.The solvents  can be  puried by  distillation before using them.