In this article
- 01 L-Citrulline 99% and Citrulline Malate 2:1: Same Base, Different Number
- 02 Reading the Two Spec Lines Side by Side
- 03 Assay Methods and What a COA Must Show
- 04 Grade, Form and Handling Differences
- 05 Documents and Supplier Checks Before a First Order
- 06 HS Classification for the Two Forms
- 07 Packing, Storage and Shelf Life
- 08 Frequently Asked Questions
Two products built from the same amino acid sit side by side on quotation sheets, and the numbers printed next to them are not the same kind of number. L-citrulline is normally offered as a free amino acid with a stated assay; citrulline malate is offered as a salt with a stated ratio. A buyer who compares 99% against 2:1 is weighing a purity figure against a stoichiometric one, and from that comparison draws the wrong conclusion about how much citrulline a kilogram actually contains.
The scope here is bulk supply for further manufacture, so the questions are about identity, assay basis, mass share and documents - not about what a finished label may say.
01 L-Citrulline 99% and Citrulline Malate 2:1: Same Base, Different Number
Both products start from the same amino acid. What differs is whether that amino acid is sold on its own or bound with malic acid, and that difference decides which figure belongs on the specification.
What does 99% refer to on a citrulline spec?
A percentage on a free amino acid is a content figure: it states how much of the declared substance the material contains, measured by a named method. Our L-citrulline powder page declares 99% with HPLC as the test, and that pairing is what makes the figure readable. A percentage without a method, without a stated basis and without naming what was measured is not yet a specification, however precise it looks.
What does the 2:1 in citrulline malate actually count?
It counts molecules rather than purity. Two parts citrulline to one part malic acid describes how the salt is built, and that description stays true whether the batch is well purified or poorly purified. A ratio says what the compound is made of; it says nothing about how much of that compound is in the bag, which is a separate line that also belongs on the specification.
02 Reading the Two Spec Lines Side by Side
Put both products on one sheet and the comparison only works if the same questions are asked of each.
Which lines belong in a like-for-like comparison?
Four lines do most of the work: the identity of the article, the figure being declared and what it measures, the method and basis behind that figure, and the citrulline content itself. The last line is what makes the two comparable, because it converts both products onto one basis and shows what a given weight of each delivers. We set out the same reading method for a different pair of forms in anhydrous versus hydrochloride betaine.
Why does the malate form weigh more per unit of citrulline?
Because part of its mass is malic acid. In the salt the two components travel together, so a given weight of citrulline malate carries less citrulline than the same weight of the free amino acid. That is arithmetic rather than quality. A formulation written in grams of free amino acid cannot simply be relabelled in grams of the salt, and a quotation that invites that substitution is inviting an error.
| Spec line | L-Citrulline 99% | Citrulline Malate 2:1 | What to ask |
|---|---|---|---|
| What the headline figure is | Content of the declared substance | Stoichiometric ratio of the two components | Which question does this figure answer? |
| What it does not measure | How the powder behaves in your blend | How much of the compound is in the bag | Ask for the other line as well |
| Method behind it | Named analytical method with a stated basis | Identity of the salt, then its own assay | What method, on what basis? |
| Mass of citrulline per unit | The full weight is the amino acid | Part of the weight is malic acid | Convert both to citrulline content before comparing |
03 Assay Methods and What a COA Must Show
A certificate is evidence only when it says what was measured and how; the figure by itself is not evidence of anything.
Which test method should be named on the COA?
The method the specification was written against, together with the marker it quantifies and the basis it is calculated on. HPLC appears on our own page for the free amino acid. A salt needs a method that separates the compound from its two components before quantifying, and the certificate should say which method was used rather than leaving the reader to assume it.
What do you do when two labs disagree?
Compare the methods first. Two laboratories running different techniques will produce different figures for the same powder, and neither is necessarily wrong. If the methods match and the figures still diverge, the sample becomes the next question: ask for the sampling plan behind it and for a retention sample that can be re-tested by a third laboratory.
04 Grade, Form and Handling Differences
Fit is decided by behaviour in your process, not by which name reads better on the quotation.
Which form suits a powder blend, and which suits a capsule?
A blend cares about particle size, flow and how the material mixes with the other components; a capsule line cares about bulk behaviour and fill consistency. Ask both suppliers for the same physical lines and compare those rather than the headline figure, because a specification written only in terms of content tells you nothing about how the powder will run. A related amino-acid ingredient is specified the same way on our L-carnosine page.
What changes in flow, solubility and hygroscopicity?
A free amino acid and a salt do not behave identically in any of the three, and the direction of the difference should be read from the specification rather than assumed from the form. Where a supplier claims an advantage in flow or solubility, ask which measurement supports it and whether that measurement is run on every batch or once at development.
05 Documents and Supplier Checks Before a First Order
Most of the doubt in a first order can be closed with paperwork, provided it is requested by name.
Which documents settle most first orders?
The specification sheet, the batch certificate of analysis, the material safety data sheet and a process flow chart. The flow chart is the one buyers skip and later need, because it shows where the material is synthesised or purified, where it is dried, and therefore which site the certificate actually refers to.
How do you separate a producer from a trader?
06 HS Classification for the Two Forms
The two forms are different articles, and that difference carries into the declaration.
Why can the two forms land in different headings?
Because one is a single chemically defined compound and the other is a compound formed from two components, and a blend of either with other ingredients is a third article again. The questions that settle it - what the goods are, what form they are in, and what they are put up for - are the ones set out in how HS classification is argued, applied here to an amino acid rather than to a carnitine salt.
When is a binding ruling worth the wait?
When the goods are new to your file, when two brokers have read them differently, or when the volume makes a correction expensive. A ruling binds the goods as described, so the description you submit is the whole exercise. Otherwise, declare precisely and keep specification, certificate and invoice describing the same article.
07 Packing, Storage and Shelf Life
A certificate describes the material at release; packing and storage decide whether it still matches on arrival.
What packing suits a bulk amino acid?
The format our pages state is a fibre drum with a food-grade inner liner, which protects a hygroscopic powder and can be closed again after sampling. Ask for the liner material, the closure, and whether the drum suits one opening or repeated sampling during production.
What changes with heat and humidity?
Moisture pickup is the main risk with a crystalline powder, and it shows as caking and lost flow rather than as a failed assay. Ask for a storage condition in writing, desiccant in the outer pack where the route is humid, and a transit plan that does not leave the drum in an unventilated container.
08 Frequently Asked Questions
Is citrulline malate the same product as L-citrulline?
No. L-citrulline is the free amino acid; citrulline malate is a compound in which the amino acid is bound with malic acid at a stated ratio. They are different articles with different specifications, and a given weight of each carries a different amount of citrulline.
Does the 99% figure mean the same as the 2:1 figure?
No. The percentage is a content figure measured by a named method; the ratio describes how the salt is built. Comparing them directly is comparing two different kinds of statement.
Which of the two should I buy?
The one your specification names. Read the label declaration you have to meet, then ask each supplier for the identity, the declared figure with its method and basis, and the citrulline content, and compare those on one sheet.
Can I substitute one form for the other in a formulation?
Not on a gram-for-gram basis. The salt carries malic acid as part of its mass, so the citrulline delivered by a given weight differs. Convert both onto the same basis before you rewrite the formula.
Can a supplier give me an HS code in writing?
A supplier can tell you how it declares the goods, but classification is decided by the importing country's customs authority. Where the answer carries commercial weight, request a binding ruling for the goods exactly as you will import them.
Request Specifications & Samples
Tell us which form you are buying - the free amino acid or the malate - with the specification you need to meet and the destination market, and we will confirm what we can supply and send the specification sheet, the batch certificate and a sample for your own trial. The discussion on this page covers the difference between the forms; availability of a specific salt should be confirmed in writing rather than assumed from this article. Commercial terms depend on specification, packing and lead time, and small initial quantities for testing are supported.
liu@wellgreenxa.com ｜ wa.me/8619890982054 - we usually reply within 24 hours.
Sources
- Our product page for L-citrulline powder - declared grade, specification, test method, appearance and certificate list, read 2026-10-28.
- No external market or regulatory data is used.
This note describes how specification and classification questions are argued. It is general information, not legal or regulatory advice, and it does not determine how any shipment is classified. Confirm requirements with the authority of the destination market.
