Comment by gavinray

Methamphetamine synthesized from pseudoephedrine gives enantiomerically pure Dextro-methamphetamine.

Phenylacetone synthesis yields racemic methamphetamine.

You can actually use a laptop screen, and polarized sunglass lenses to check the optical rotation at home, cheap polarimeter.

As far as purifying enantiomer with amphetamine and methamphetamine goes:

It can be done relatively easily with just D-tartaric Acid.

Look up "Procedures for the Resolution of Racemic Amphetamines"

https://erowid.org/archive/rhodium/chemistry/amphetamine.res...

I do not believe this practice is in use in illicit drug manufacture. There's no economic incentive and it requires some braincells.

From "Selective Crystallization of Methamphetamine with d-Tartaric Acid:"

  Phenylisopropylmethylamine was resolved by treatment with 0.4-6 moles of dextro tartaric acid in water or aqueous ethanol containing 0.4-6 moles hydrogen chloride.

  A mixture of phenylisopropylmethylamine 150, d-tartaric acid 82.5, and H2O 330 g was treated with HCl to pH 4 to deposit 120 g L-phenylisopropylmethylamine-d-tartrate salt, which gave 88 g L-phenylisopropylmethylamine. The D-enantiomer (58 g as the HCl salt) was isolated from the filtrate.