two labs a point or two apart on the

is a tailing factor of anything specific a problem

baseline drift on a gradient is normal. baseline drift on an isocratic hold is your column

a warm transit can put a visible degradant peak on a chromatogram. that is what 15 days at ambient does

how much sample does a lab actually need for identity as well as purity

a dimer usually shows up late and at roughly double the mass. the chromatogram alone will not tell you

why does integration change the number so much

thats a charge state

deamidation is about plus 0.98 Da. it is not a rounding error, it is a degradant

thats the solvent peak

oxidation is about plus 15.99 Da and is usually methionine or tryptophan