Over the course of my studies, my lab coat has absorbed a non-negligible amount of different chemicals, some of them nasty organic polymers, some are more insoluble inorganic compounds like $\ce{Cr2O3}$.
Even after washing the lab coat some stains remain. Is there a way to get rid of those, or should I rather buy a new lab coat?
A lab coat will eventually get dirty, that's why it is a good idea to wear it. I had a lot of students complaining about the condition of their coat and they asked me if they could just wash it in the washing machine. My answer was always no.
As far as I remember - I am a theoretician now - a labcoat costs much less than a pair of trousers and a T-shirt. It should be renewed annually and disposed of according to the norms how you would dispose of an unknown chemical. You never know where the chemicals incorporated in your coat will end up, so dispose of them as safely as you can.
In some countries, it is required by the employer to provide equipment like that and taking care of either cleaning or disposing of it eventually. (In Germany that should be the case.) Wear it as a disposable layer of protection and please - for the safety of the environment and yourself - do never ever put it in a normal washing machine again.
As an additional note, if you wash it in the same washer like your normal clothes, how can you assure that it will not end up in your everyday clothes? I can imagine, that having chromium whatever in my underwear would not make me feel alright.
Lab coats, like other forms of PPE, are supposed to provide a final barrier of protection, for when all other risk mitigation strategies have failed. They are not just an expensive form of a fancy cooking apron. If you are getting spills on your lab coat, you should take this as an opportunity to re-examine your laboratory techniques to try to establish why this is happening.
Contamination (including wiping hands) on lab coats should be treated at the time of incident, and contaminated lab coats should not be removed from the laboratory, unless in a contaminated laundry or waste container. Most workplaces will have a well-defined plan for laundering lab coats, and strict guidelines for how often this should be done. You can search for just how common this is.
Good lab coats can be expensive, but think of them a little like fire extinguishers. Most days in the lab, you shouldn't even need one. However, you want to make sure that when you DO need them, they will work properly and do the job they are designed for. Regular laundering of a non-contaminated lab coat will keep it in top condition, but once contaminated with hazardous chemicals that cannot be safely neutralized, they should then be replaced.
So, the answer to your question is: no, you should not attempt to launder your lab coat. Buy a new one.
And a final 2 cents worth: Dirty lab coats are not a badge of honour; they are a sign of a sloppy chemist.
You should never wash your own lab coat. That defeats the whole purpose of lab coats: separating yourself from the potentially hazardous chemicals you work with.
But your employer may have a program for laundering lab coats. My university has a program for safely and properly laundering lab coats. This way you can keep it reasonably clean until replacement.
Use or discard. There is no "clean." DuPont Teflon Advanced or an old can of perfluoroctanesulfonate Scotchguard for the new lab coat? Classic Scotchguard,
An eaten lab coat decorated with holes, stains, and blackened smears of stopcock grease along the sides is a badge of honor. You keep a pressed new one aside for when hominims in suits visit (JAFOs). Formal occasions demand the Black Lab Coat. They cannot be purchased. As with lightsabers, you must make your own. Given the potential toxicity of aniline black, one recommends starting with a new 100% cotton lab coat washed (remove sizing) and double rinsed. Then, Procion MX and/or Cibacon F reactive blacks (and lots of non-iodized salt).
http://www.worlddyevariety.com/disperse-dyes/disperse-blue-354.html
If you are a polyester sort of fellow, Foron Brilliant Blue disperse dyes.
