Peptides made by standard synthesis usually come out as a salt, bound to a counterion such as trifluoroacetate (TFA) or acetate. The counterion adds weight to the powder, which is one reason net peptide content is lower than the total powder weight.
Counterion
The charged molecule bound to a peptide in its salt form, such as trifluoroacetate or acetate.
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Purity does the work these terms describe: batches held until their lab report is in, payments matched to orders, and wording checked before it sends.