does purity by hplc at one wavelength miss things

my 20mg vial weighed more than 30mg of powder, is the certificate lying

the font on this one changes halfway down, am i being paranoid

if the certificate date precedes the lot date, ask. sometimes it is sloppiness and sometimes it is not

coming back after 7 months, has the pinned reading guide changed

ask for water content

is sterility tested as part of a normal purity certificate

does anyone keep a folder of certificates to compare over time

purity is not assay

whats the minimum a certificate has to have before you take it seriously

thats a tell

the paperwork can be perfect and the vial can still be light. weigh it

ask for water content

looks re-dated

the three way match is vial, certificate, invoice. if all three agree you have something