So don't follow what I said in my first comment. Same idea though:

Convert 50mg to micrograms (Google). Dissolve the 50mg in enough vodka/distilled water so that your solution comes out to 5 micrograms per ml.

That will be a lot of microdosing solution. If you aren't using it all at once, you may want to use vodka and keep your "master batch" in a freezer for long term storage.

BTW, did you jump through some hoops to get this L? Or did some person sell you a bag of something saying that it was LSD? Real raw L is expensive (a few $k/g IIRC) and seems like an odd choice for microdosing. But I do recall a friend who had gels, as well as a diluted granulated L stuff. It was colored, and 1g=100ug of L or something like that.