Eugene is correct. High purity is rare in street amphetamines and MDMA.
The types and quanitities of impurities vary widely depending on the source
of the base chemicals and synthesis process. The output on a chromatograph
is usually quite noisy. The primary culprits are 1) Poor temperature
regulation during synthesis, and 2) low quality base materials. I have
heard stories of people using things like formaldehyde that has been
previously used to preserve biological specimens, and fingernail polish
remover as a source of acetone. Neither of these sources is pure base
chemical, nor are the base chemicals they contain particularly pure to begin
with anyway.
Many of the impurities found in the MDMA/amphetamine class of drugs are
neuroactive/neurotoxic in some manner and almost invariably can result in
cumulative neurological damage. In the long run, use of "street"
amphetamines results in non-trivial damage to the central nervous system and
liver.
>> I think I also heard MDMA was neurotoxic, especially to substantia
>> nigra?
>A very old rumor which has been disproven. Check the MAPS web site.
The only biological damage I am aware of for pure MDMA is to the liver
(which is common for many types of drugs).
-James Rogers
jamesr@best.com