ZHICHENG BIO
01Buyer guides
Raw material buyer guides
For buyers and formulators: how to write a specification, how to read a certificate, and the things suppliers usually leave out. Specification, analysis and regulation only — no health claims.
Fisetin oral exposure: what unformulated 98% powder actually deliversThe human PK arithmetic on fisetin, done in full — and what it means for anyone specifying the raw material.
Why “98% by HPLC” does not describe dihydromyricetin qualityDHM has two chiral centres, and the standard assay cannot see either of them. What to specify instead.
How to buy bulk fisetin: five questions that separate one “98%” from anotherBotanical source, related flavonoids, urushiol, quercetin interference, and writing a spec where no monograph exists.
How to buy bulk dihydromyricetin: grades, source and the specification most buyers missThe grade ladder, vine tea sourcing, China's 2026 approval, solubility, and the specification line most buyers never write.
Sourcing amino acids from China: a due-diligence guide for buyersMonograph grade vs feed grade, reading a CoA properly, trader vs manufacturer, lead times and Incoterms.
Silymarin 80%: the number is meaningless until you know which method produced itWhy an 80% silymarin certificate and a 55% silymarin certificate can describe the same drum — and how to tell which one you are holding.
Quercetin 95%: 95% of what, exactly — the dihydrate or the molecule?Ten percentage points of quercetin hide inside a question nobody asks the supplier: which basis is the assay on?
Citrulline malate 2:1: what the ratio means, and what NMR found in the drumsTwo ambiguities and one published measurement, worked through in citrulline kilograms.
Glucosamine: two certificates reading 99.5% that differ by 40% in glucosamineThe USP monograph gives you every number needed to prove that the two salts are not interchangeable — and then reports the assay in the units that hide it.
L-ergothioneine: the authorised novel food is an enantiomer, and your assay probably cannot see itA regulatory name, a transporter, and an assay that is blind to the difference between them.
L-carnitine: the pharmacopoeial assay is a titration, and a titration cannot see chiralityA 99.5% assay figure on an L-carnitine certificate is a statement about carnitine, not about levocarnitine. Here is what the monograph does and does not lock down.
L-theanine: when someone put six commercial products on a chiral column, five contained D-theanineThe only guide in this set where the failure rate has actually been counted — and it was five out of six.
Epicatechin 90%: the catechin peak in your chromatogram may be a processing artefactA flavan-3-ol certificate is a report on two chiral centres that the method used to produce it cannot resolve.