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Eight articles about the things that decide whether material is any good: what each line on a certificate measures, why the milligrams on a label are not milligrams of peptide, and where the cost of a long chain actually goes. Every example in them is a real lot from this catalog, linked to its own certificate, because an article about paperwork that cannot show you the paperwork is an advertisement.
Reading a chromatogram
One peak is the answer everyone wants. What the shoulders, the late cluster and the flat stretch before it are telling you.
Read itReading the paperwork
Why we pay for a second laboratory
The manufacturer tests its own material at release. That is normal, necessary, and the one party with an interest in the answer.
How to read a certificate of analysis
What each line on a COA is actually measuring, in the order it matters, and the four things a weak certificate leaves out.
What a blend is, and what its certificate should say
Several peptides co-lyophilized into one vial is one lot number and several different purity questions.
Net peptide content, and the 18% error nobody catches
Why the milligrams on the label are not the milligrams of peptide, and what that does to a concentration you already wrote down.
What a lot number is for
The FDA has documented batch numbers being rewritten a tier upstream. Here is what that means for the document in your hand.
Purity is not potency
HPLC, mass spectrometry and Karl Fischer each answer a different question. Three suppliers quoting "99%" may be quoting three different things.
How it is made
Thirty-nine residues and a fatty acid
Why the metabolic analogues are all roughly the same length, what the diacid on the lysine is doing there, and why they cost what they cost.
Why a forty-residue peptide costs what it does
Solid-phase synthesis is the same operation repeated once per amino acid. The arithmetic of that repetition is most of the price.
The two-residue peptides
At the other end of the shelf from the metabolic analogues sit chains of two, three and four amino acids. Almost everything about them is different.
Where the word peptide stops meaning anything
A working definition, the boundary with proteins, and the two things in this catalog that are not peptides at all.
Formats
Handling
Milligrams, micrograms and the units that are not weights
A factor of a thousand, a factor that is not a factor at all, and where the decimal point actually goes.
What minus twenty is actually for
Cold slows three different degradation routes at three different rates, and one of them is not slowed by cold at all.
Where the line is
15 pieces. Nothing here is medical advice and nothing here is a claim about what any of this material does in a person — it is all supplied for laboratory research use only.