What’s hidden behind your cosmetics labels? Chromatography!

Not all that glitters is gold, but this post certainly is. Have you ever wondered about the foundation of your foundation? The ingredients on the label of your organic hand cream? Well, I’m here to tell you that, surprise, chromatography has most likely had a hand in making your make-up. If you are curious about the role of flash and prep chromatography in the cosmetics industry, read on to get some insights.

I was chatting with my daughter the other day and we reminisced about her teenage years. She told me that she found it very difficult to explain to her friends what her father, a chromatography specialist, does for a living. Then one day she had a few girlfriends over and when they asked me about my job, I told them that I work on the machines that help make ingredients for their lip gloss and face cream. She said that I got a few bonus points for this and she continued to use this explanation for years.

Chromatography is so widespread, it can really be found in any field for any application. But in case you are wondering if we really use the technique in cosmetics, the answer is a clear bold YES.

In fact, since cosmetics is in the business of putting products on your skin and chromatography is in the business of achieving the purest products, these two couple better than a smoky eye and a nude lip.

But I suppose you will like more than a skin-deep explanation about how to use flash chromatography and preparative HPLC to produce sunscreen and eye shadow. So here it goes!

During cosmetics production, chromatography systems are typically used in the initial part of the process, during ingredient discovery and purification. Active constituents used in cosmetics can either be synthesized in a laboratory or extracted from crude natural products. Natural product extracts often consist of hundreds of compounds and you often need to isolate a single compound of interest from the mixture.

Most commonly, we perform the initial isolation by flash chromatography to pre-fractionate and reduce the number of components in the mixture. Then we follow up with a final purification by prep HPLC.

Flash chromatography is suitable for the purification of high quantities of both synthetic and natural products. It is an ideal technique for rapid fractionation of crude extracts or coarsely purified fractions. When we use flash chromatography, our main goal is to reveal the most active fractions in the mixture, so that we can correlate their bioactivities to the molecules that they are made of.

For isolation of active ingredients, the sample can be introduced either by liquid or solid loading to a cartridge. Typically, we use normal phase or reversed phase silica with a particle size range of 15 to 50 µm as a stationary phase. Often, we need to collect several fractions for further characterization, bioactivity testing and further purification by HPLC.

Speaking of preparative HPLC, this method is usually used in the final step of bioactive material purification. For the technique, we most often inject the sample via liquid loading on a steel column with silica as the stationary phase.

Preparative HPLC is a fast, flexible and robust method of separating compounds from complex mixtures at high purity.

The technique has a better resolution than flash chromatography because of the smaller particle size of the silica, among other reasons. The smaller silica size of the stationary phase, around 5 to 15 µm, results in a bigger surface with which the solute and sample can interact. This improved interaction between mobile and stationary phase increases the resolution. I’ve already written about resolution in chromatography in a previous blog post in case you want to get a better grip on this.

Another point I want to bring up is the type of stationary phase and mobile phase, or solvent that you choose when making cosmetic products. As expected, the material you select for isolation of natural products by chromatography depends on the type of compounds present in the extract and the extraction process used prior to the purification. For example, the extract of a plant obtained with aqueous ethanol will be substantially different than compounds extracted with hexane.

Certainly, polarity of the compound mixture is a major factor in selecting the type of mobile or stationary phase in your purification.

If you are curious to find out more about cosmetics production, check out our series of COSMETICS LAB magazines, “Cosmetics made with care” and “The science behind the ingredients”. And more issues are still to come!

Meanwhile, I hope this post has made you blush with so much pleasure, no application of actual blush is necessary for your complexion. Sorry, I couldn’t resist popping this one in there.

As for my daughter, she is now older and times have changed. She told me that me she now prefers to explain my job to people by telling them I work on machines that help produce cannabis actives. I conceded that since cannabinoids can also be used in cosmetic products, this could indeed be a win-win scenario. Either way, my job is pretty amazing.

Till next time,

The Signature of Bart Denoulet at Bart's Blog