Look up Dragendorff′s reagent - it’s been used with PEGs.

Hello Juan Manuel Casas-solvas,

another possibility I see is with TLC plates with fluorescent indicator. Your substance spots should then be visible as dark spots on the plate when you illuminate the plates with UV light. Typically

the UV indicator glows at 254nm.

Many greetings

Joachim Horst

Thank you for you answer, Joachim. We always use fluorescent (254 nm) TLC plates, but most of regular organic compounds do not absorb above 200 nm, so no dark spots can be seen on the plate. So is the case of PEGs.