If you’re new to chromatography, the technical jargon and complex diagrams can be overwhelming. But what if we break it down to its most basic building blocks? Using first principles thinking, we can strip away the complexity and build a clear, logical understanding of chromatography from the ground up.
At its core, chromatography is a separation technique. It’s a method scientists use to separate the different components of a mixture—whether that’s ink, plant extracts, or even blood—so they can be analysed, identified, or purified.
Most substances in the real world are mixtures. To study or use the individual parts, we need a way to separate them. Chromatography is one of the most powerful and versatile tools for this purpose.
Let’s break chromatography down into its most fundamental concepts:
A mixture is simply two or more substances combined, but not chemically bonded. To analyse or use the individual components, we need to separate them.
Chromatography always involves two phases:
Each component in a mixture interacts differently with the stationary and mobile phases. This is called affinity:
All chromatography techniques use these same principles. Some common types include:
Each component’s unique chemical properties—like polarity, size, and solubility—cause it to spend more time in either the stationary or mobile phase. Over time, these differences cause the components to spread out and separate.
Imagine a crowd of people (the mixture) walking across a sticky floor (the stationary phase) while a strong wind (the mobile phase) blows. Some people get stuck more and move slowly, while others move quickly with the wind. Over time, the crowd spreads out based on how sticky their shoes are (their affinity).
Chromatography is all about exploiting differences in how substances interact with a stationary and a mobile phase to achieve separation. By understanding these basic interactions, you can grasp any type of chromatography, from the simplest paper method to advanced HPLC systems.