A request for phycocyanin powder usually comes back with one of three labels: a percentage, an E-designation, or a figure ending in K. Buyers compare them as three points on one scale. They are not, and treating them as comparable is the most expensive mistake in this category.
This article sets out what each label anchors on, why an assay cannot be read against a colour strength, and what to request before two lots are compared. Read phycocyanin powder specifications in that order and the grade question usually answers itself.
01 What the Specification Line Actually Says
A phycocyanin powder specification is one short string that carries more weight than its length suggests.
What does the grade field on an offer actually state?
On most sheets it states one value beside specification, assay or grade, without saying what that value was measured against. Our pages list food grade, a percentage and an HPLC method, which together describe a content measurement. A competitor may put an E-designation in the same position. Both look like a grade; only one is one.
Why does the same product carry three different specification lines?
Because the three lines answer three questions, and each trade channel settled on the one its customers asked. A buyer formulating to a declared content wants the percentage. A buyer matching a colour target wants a strength designation. A buyer repeating a historic order wants whatever scalar the last supplier printed. None is wrong, and none is interchangeable.
02 Three Label Families Sell Into the Same Market
The families coexist because they serve different purchase routes, and most offers do not name which route they were written for. Our blue spirulina phycocyanin page is written on the content route; other offers are not.
Where did each label family come from?
Each grew out of a different way of specifying the same material. Content figures come from analytical chemistry and answer how much compound is present. Colour designations come from the colorant trade and answer how strongly it colours a preparation. K figures appear to come from commercial grading, and the published basis behind them is not something we can confirm.
Do buyers ever see all three on one quotation?
Rarely on one line, often across two offers. A buyer shortlisting three offers can receive a percentage from one, an E-designation from the second and a K figure from the third, then rank them by which number looks bigger. That ranking is meaningless: they are not measuring the same property, and two of them may not measure content at all.
| Label on the offer | What it appears to anchor on | Comparable with the other two? | What to request in writing |
|---|---|---|---|
| Assay percentage | Content of the named compound, by an analytical method | Only against the same property and method | Method with its reference, and the basis of calculation |
| E-designation | Colour strength derived from absorbance of a preparation | No, it measures a different property | Concentration, path length and the method used |
| K figure | A commercial scalar, basis not stated on the sheet | No, and not even between two suppliers | A statement of what the figure scales against |
| Unqualified product name | Nothing measurable on its own | No, it is not a specification | Which of the above, and on what basis |
| Two labels on one sheet | Two separate measurements, not two grades | Only line by line, each with its own method | A separate method and basis per line |
03 Why an Assay Percentage and an E-Value Are Different Measurements
The two most confused labels differ in what they measure, not in strictness.
What is the percentage measured against?
A content figure states how much of the named compound the method found, and the method decides the answer. A chromatographic separation resolves the pigment from related compounds; a spectrophotometric reading responds to absorbance other pigments also produce. Two offers can print a percentage while measuring differently, which is why the method belongs beside the number.
What does an E-designation describe instead?
In the colorant trade, an E-designation is read as a strength value derived from the absorbance of a preparation at a defined concentration and path length. It describes how strongly the material colours, not how much pigment the powder holds. Material can be strong in colour and modest in content, or the reverse, because the two move independently.
04 What a 10K Label Communicates to a Formulator
A K figure is the least self-explanatory of the three, which is why it causes the most trouble.
What does the K figure scale against?
The label does not say. In practice it ranks material within one supplier's range, and what it scales against - colour units, a dilution series, or an internal reference - has to be established in writing. Two suppliers can both list a K figure and mean different things, and nothing on either sheet reveals it.
What changes in a formulation when the basis is unstated?
Everything downstream of the dosage decision. A formulator who reads a K figure as a content percentage calculates an inclusion rate against the wrong property, and the error does not appear at mixing but at the colour check, or later in shelf life. An unstated basis is a formulation risk, not a documentation nuisance.
05 Reading a Phycocyanin COA Line by Line
A certificate releases a lot against a specification. It confirms conformity at a point in time, and it can only be compared with another certificate written on the same basis.
Which lines let two lots be compared at all?
The material description, the measured property, the method with its reference, and the basis the figure is calculated on. Our guide to reading a certificate line by line follows the same sequence for another material, and the logic transfers unchanged.
Which values fall outside the certificate's scope?
Anything about performance in your process, or about a property the certificate did not measure. A content certificate says nothing about colour strength; a colour certificate says nothing about content. When both are needed, both have to be asked for, each naming its method. Assuming the unmeasured property follows is the most common source of grade mismatch.
06 Colour Fade Is the Failure Buyers Notice First
Whatever the label says, the property that decides acceptance in most applications is whether the blue holds, and that is assessable without a laboratory.
Why does the pigment lose intensity before anything else shows?
Because colour is the most sensitive visible property of the material. Degradation of the chromophore reduces absorbance directly, so the shade weakens while the powder still looks like a uniform blue solid. Nothing on the certificate predicts this and nothing on the label warns about it. The same reading of colour as an early indicator applies here, on a pigment whose value is its colour.
Which handling steps accelerate it?
Light, heat, oxygen and moisture, and they compound. Opening a container repeatedly is the step most often overlooked, because each opening exchanges the headspace and exposes the surface. A lot acceptable at intake can lose intensity during handling, which is why storage belongs in the specification.
07 Light, Heat and the Packing Response
Packing is the part of the specification that keeps protecting the property the label describes after the container closes.
Which packing format limits exposure?
An opaque barrier rather than a clear one, a sealed liner rather than an open drum, and minimal headspace for the fill weight. The container also has to survive the journey with its liner intact, since a barrier that fails in transit protects nothing. For a pigment that is the difference between the material at release and at use.
What changes between a sample and a drum?
Exposure accumulates with handling. A small sealed sample is opened once and reflects the lot closely; a drum is opened, sampled, resealed and stored, and each step adds exposure. That is why a sample can look correct while the drum does not. The handling notes for spirulina powder follow the same pattern.
08 Where Grade Substitution Breaks an Application
Substitution problems start with a label that looked interchangeable and end with a batch that does not match.
Which applications can absorb a label difference?
Where the final colour is corrected downstream, or the pigment is a minor component, a basis difference may never show. Where the pigment is the visible value - a blue beverage, a confection, a coating - it shows immediately, because the same inclusion rate produces a different shade. Decide which category applies before comparing.
What fails first when the wrong label is used?
Colour in the finished preparation, usually at the first production run rather than in a stability study. The batch comes out lighter or duller than the approved reference, and the cause traces back to a specification line that never described the same thing. Verifying the supplier is the step that settles it, because the answer is a written basis, not a certificate alone.
09 A Pre-PO Checklist for Phycocyanin
Five questions settle the grade question for phycocyanin powder, and all can be answered before a purchase order exists.
Which five questions settle the grade question?
- What property does this figure measure, and on what basis is it calculated?
- Which method produced it, named with its reference?
- Does the certificate state the same basis as the quotation?
- If colour strength matters, is a strength figure provided separately, with its own method?
- Which export documents accompany the shipment, including the classification the destination requires?
What should a first sample confirm?
Confirm the shade against the certificate in daylight, confirm the powder disperses as the process expects, and keep the certificate for the sample's lot. Where a colour target governs acceptance, test it in your own preparation rather than on the powder alone. Our bulk powder sourcing notes cover how that request is framed.
10 Frequently Asked Questions
Is 10% the same as E18?
No. One is a content figure from an analytical method; the other a strength designation from the colorant trade. They measure different properties, and nothing links them without the basis behind each.
Can a 10K phycocyanin powder replace a percentage grade?
Only if the supplier states in writing what the K figure scales against and how it relates to the content you require. Without that statement the labels cannot be matched, and a trial is the only honest test.
Why do suppliers list only one label?
Because each writes for the customer it usually serves. That is a habit, not a limit, and a supplier able to produce both figures with their methods is telling you something about its analytical capacity.
What if my specification requires a colour strength?
Ask for the strength figure with the method, concentration and path length used. Without those three it cannot be set against any reference you hold, including your own previous lot.
Which documents settle the question?
The specification sheet, the lot certificate, and a written statement of the basis behind whichever label appears on the offer. Where classification matters, request the accompanying code with the shipping documents rather than relying on a listing.
11 Request Specifications & Samples
If you are qualifying this material against a label you already hold, send that label and the property it is meant to control. We will state the basis our figure is calculated on, name the method, and say plainly where the two do not match, rather than a number that appears to.
Email liu@wellgreenxa.com or message us on WhatsApp with your target specification for phycocyanin powder. We reply within 24 hours. If a colour target governs your acceptance, say so in the first message - that detail decides which basis we discuss.
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