Percentages on the bottle: how a buyer reads a Korean ampoule

Most brands print the name of an active and say nothing about how much of it is there. The buyer sees "with niacinamide" and cannot tell whether that is five per cent or half of one — and the gap between those two numbers is the gap between a working product and marketing.

The Korean brand aoi, made by Red Purple Blue, did the opposite: it prints the concentration of the key active on the bottle itself, in per cent and in ppm at once. That makes it a convenient case for unpacking what such figures actually mean.

Why concentrations are rarely printed

Stating a concentration is unattractive when it is low and risky when it is high: the manufacturer takes on a commitment that a laboratory can check. So most stop at the INCI list, where ingredients run in descending order but without numbers.

When a figure is named, it acquires a second function: it sets the frame of the conversation. With a brand that wrote "niacinamide 5%" you can discuss the formulation, equivalents and market adaptation directly. With a brand that wrote "with niacinamide" the conversation starts with finding out what is inside at all.

Per cent and ppm are the same thing written twice

One per cent equals ten thousand ppm. Niacinamide at 5% is 50,000 ppm; sodium hyaluronate at 0.5% is 5,008 ppm in that particular formula. The second notation earns its place where an active is small by weight but expensive: "0.0015%" is awkward, while "15,000 ppm" reads clearly.

aoi applies this consistently. Lumi Drop states niacinamide 5% and rice bran water 41%; Regen Drop states Sodium DNA 1.5% and ginseng root water 42%; Hydra Drop states sodium hyaluronate 0.5% and camellia sinensis water 45%. The first figure carries the action, the second shows what the base is built on.

An irritation index of 0.00 — what it is and is not

The irritation index comes from a closed patch test: the product is applied under occlusion, usually for twenty-four hours, and a physician then grades the reaction on a scale. Zero means no reaction was recorded in any participant. All three aoi ampoules state an index of 0.00 from testing by the Korea Institute of Dermatological Sciences, November 2025.

What it does not mean: it is not proof of efficacy and it is not a certificate. It is a tolerance test, not a results test. It does matter in markets sensitive to claims for compromised skin — pharmacy retail above all.

What to ask the supplier

First, whether the report exists on paper and which products it covers: the test is run per product, not per brand. Second, how many participants took part and under which method the grading was done. Third, whether the formulation in the report matches the current batch, because the formula may have been revised since.

And one question on concentrations specifically: is the figure the share of the active itself, or the share of the solution it is supplied in? That is the most common source of discrepancy between the packaging and the specification sheet.

Sources

Prepared from data provided by Red Purple Blue Co., Ltd (the aoi brand) and published with the company's written consent for presentation on the Teranova Group platform. Stated properties, formulations and concentrations are as given by the company.