A portable UV detector won't give you the information you need for various solvent samples. A portable Raman might. But you have to know how to use this instrument, its not a point and click.
You're not yest clear enough with us on what your plan is, what scale, what scope and what expertise you have.
For cGMP or ISO 9001:Six Sigma compliance, you need an expert and validated processes in place. On the other hand, if you're supplying reagents you've purchased in bulk for hobbyists, you can forego testing, just let your supplier know that you want a CofA, and you expect to hold them to it -- that's just being a businessperson, a handshake and a promise for and from everyone involved.
See, when my car needs repair, I take it to the dealer or someone certified in auto repair, not someone holding a book open on there lap going "OK, this bolt here ..." But, when I buy alcohol at the hardware store for cleaning a part, I take their word for it. Where are you on this continuum?