Question

A chromatogram of a peak provided a retention time at 5,4 minutes and 0.41 base width of the peak. The number of plates or the peak obtained is:

• A. 210.7
• B. 173.5
• C. 78.4
• D. 2775.5

Answer 1

The Correct Option is B

To determine the number of theoretical plates (\(N\)) in chromatography, we use the formula:

\(N = \left(\frac{t_R}{W}\right)^2 \times 16\) 

Where:

• \(t_R\) is the retention time.
• \(W\) is the base width of the peak.

Given:

• Retention time (\(t_R\)) = 5.4 minutes
• Base width of the peak (\(W\)) = 0.41 minutes

Substituting the given values into the formula:

\(N = \left(\frac{5.4}{0.41}\right)^2 \times 16\)

Calculating the ratio:

\(\frac{5.4}{0.41} = 13.17\)

Plug this back into the formula:

\(N = (13.17)^2 \times 16\)

First, calculate the square:

\(13.17^2 = 173.5289\)

Finally, calculate the number of plates:

\(N \approx 173.5\)

Therefore, the number of plates is approximately 173.5, which is option (b).