How Mass Spectrometry Works

Ever wondered how scientists can identify mystery substances in crime labs or pharmaceutical companies? Mass spectrometry breaks this process down into four straightforward steps that work together like a molecular assembly line.

Ionisation is the first crucial step where neutral molecules get turned into charged particles. For lighter substances, electron impact smashes high-energy electrons into the sample, knocking off electrons to create positive ions $X → X⁺ + e⁻$. Think of it like a molecular game of snooker! For heavier molecules, electrospray ionisation works more gently by adding a proton from a solvent $X + H⁺ → XH⁺$, creating ions without breaking them apart.

Acceleration comes next, where all the positive ions get pushed through an electric field. Here's the clever bit - they all gain the same kinetic energy, which means lighter ions zoom off faster than heavier ones. It's like giving runners of different weights the same push - the lighter ones will sprint ahead!

The final steps involve ion drift through a flight tube and detection at the end. When ions smash into the detector plate, they create an electrical current that's proportional to how many ions are present. This data gets processed by a computer to produce a mass spectrum - essentially a graph showing you exactly what's in your sample.

Key Point: The whole process relies on the simple principle that lighter ions move faster than heavier ones when given the same energy boost.