Article by: Perry Romanowski
I must confess. One of my favorite things about being a chemist is getting to say long words and knowing what they mean. I loved learning the IUPAC system for naming chemicals.
That’s why I found ingredient lists on shampoos & conditioners baffling. I didn’t know what most of the chemicals were. They were similar to IUPAC terms, but not quite. It turns out that the cosmetic industry doesn’t use the IUPAC naming system. Instead, they follow their own system as laid out in the International Nomenclature of Cosmetic Ingredients (INCI) dictionary. This volume is produced by the main cosmetic industry trade group called the Personal Care Products Council (PCPC, formerly the CTFA but we’ll save that for another time).
List of Ingredients
The first thing to know about cosmetic ingredients is the ingredient list. In the United States, every personal care and cosmetic product is supposed to have their ingredients listed. In the business, we called it the LOI (list of ingredients). Any ingredient above 1% is required to be listed in order of concentration (by weight). At 1% or below, the ingredients can be listed in any order. Typically, preservatives and dyes are listed at the end. In a future post, we’ll show how this labeling requirement can help you formulate new products.
Any ingredient above 1% is required to be listed in order of concentration (by weight).
To be proper, companies are supposed to follow the naming conventions as laid out in the INCI.
Cosmetic Ingredient Naming Conventions
While many chemical names in the INCI seem arbitrary, there are some standard rules. The following will help you make heads or tails out of the ingredients on most LOIs. We can’t list all the conventions here, but we’ll point out the major ones and give examples.
When they first came up with the INCI (originally called the CTFA Cosmetic Ingredient Dictionary) in 1973, many cosmetic ingredients already had names. These common names were incorporated into the dictionary even though they didn’t follow any specific naming rules. Therefore, we use Glycerin instead of the more accurate Glycerol and Menthol instead of (1R, 2S, 5R)-2-isopropyl-5-methylcyclohexanol. Common names are also used for various natural ingredients like Lanolin and Beeswax.
Probably the most important thing to learn about naming cosmetic ingredients is to memorize this list of hydrocarbon stem names. It’s a bit different than the IUPAC.
So, if you have a 16-carbon alcohol, you call it Cetyl Alcohol instead of Hexadecanol. For an 18-carbon acid, you would use Stearic Acid instead of Ocatdecanoic acid.
You’ll run into names like Cocamidopropyl Betaine that don’t match any of the stem names. This is because the raw material uses coconut oil as a starting raw material. In these cases, you use an abbreviation of that starting material. Other ones you might see include Palm Kernel oil, Soybean oil and Sunflower oil. In a future post, we’ll show the fatty acid distribution of these materials.
The INCI tries to follow established conventions from other systems. For example, when you want to name an ether, you take the stem names from both fatty acids and add the term ether. Thus, a molecule made with a 14-carbon and 16-carbon chains connected by an oxygen would be called Cetyl Myristyl Ether. An ester of the same molecules would be Cetyl Myristate.
Hydrocarbons that contain nitrogen are amides and have the phrase included in their name. Therefore, Lauramide is used to describe a 12-Carbon molecule (Lauryl) that has a NH2 group on its end. If the Nitrogen has other hydrocarbons attached, those are also named. So, Lauramide DEA would be that same 12-Carbon molecule attached to a Nitrogen which also has Ethyl groups attached to it. When these Nitrogen containing compounds are turned into salts, the suffix “-monium” is added. So, a 16-Carbon attached to a Nitrogen with three methyl groups is Cetrimonium Chloride.
A variety of conventions are used to name polymers. For Nitrogen containing polymers, the term “Polyquaternium” is used. There is also a number associated with the ingredient but it doesn’t refer to anything chemically. It just happens to be the order in which the material was registered.
Other polymers use common abbreviations. PEG is Polyethylene Glycol. PPG is Polypropylene Glycol, etc. Then a number is included to refer to the moles of ethoxylation in the polymer.
For silicone containing materials, terms like Dimethicone, Cyclomethicone and amodimethicone are used. Whenever you see some form of these words in a chemical name, you know there is some silicone in it.
Ten years ago, you used to see the abbreviation FD&C in front of many chemical colorants. Today, however, the INCI has adopted a simplified method for naming colors. They just list the color followed by a number (e.g. Yellow 5). This doesn’t tell you anything about the chemical composition but you can get the structure by looking it up in the INCI. An alternative naming system is the EU one in which each colorant is assigned a 5-digit chemical index (CI) number. Yellow 5 in the EU is called CI 19140.
There are many other rules that you’ll have to learn over time. To give you a flavor here are a few more.
- Water is just called Water. (Not deionized or purified or anything else. Just water)
- Fragrance is called Fragrance no matter what compounds are used to make it. This is changing but for now, it’s correct.
- Botanicals use the Latin name of the plant or part plus the term Extract. So, if you use an ingredient taken from the leaf of a lemon, the ingredient is called Citrus Medica Limonum (Lemon) Leaf Extract.
The naming of raw materials in cosmetics share some characteristics with the IUPAC system you learned in Organic Chemistry. However, there are many differences and for some things it is impossible to determine the chemical structure from just the name. For more information, your best bet is to go to your company’s library (or your city’s) and take a look at the latest version of the INCI.
Do you have any ingredient naming questions? Leave a comment below and let us know.