# How do I calculate the number of theoretical plates in gas chromatography?

##### 1 Answer

#### Answer:

There are several formulas, but the most common one is based on the assumption that the peaks are Gaussian curves.

#### Explanation:

The number of theoretical plates

Gas chromatography columns normally have

The number of theoretical plates is related to the retention time,

If the peaks are reasonably symmetric, it can be assumed that they have a Gaussian shape. Then

where

You find the peak width at half height by drawing a line vertically from the peak maximum to the baseline, measuring half-way up the peak, drawing a horizontal line, and measuring the length of the horizontal line.

You measure the retention time (designated avove as

Both

**EXAMPLE**

A chromatogram from a certain column has a peak with a

**Solution**