14. Base your answers to the next two questions on the following chromatograms o

Question

14. Base your answers to the next two questions on the following chromatograms of compounds A and B, which were obtained at the same flow rate with two different columns of equal length: Colume 2 10 12 Tme A. Which column has a larger plate height? A) column 1 B) column 2 C) the plate height is the same for both columns D) plate heights cannot be compared based on the information given B. Which compound has a greater partition coefficient? A) compound A B) compound B C) the partition coefficient is the same for both compounds D) partition coefficients cannot be compared based on the information given

Explanation / Answer

Q 1] Which column has larger plate height?

Answer: Option “D”

Justification: For determination of plate height we need to calculate the theoretical plate (N) and it is calculated as follows

Theoretical plate (N) = 5.54 [Tg/Wh]

Where ,            N = Number of theoretical Plate, Tg= Retention Time and Wh= Peak width of half height (in unit of time)

Columns with high plate numbers are considered to be more efficient, therefore have higher column efficiency, than columns with a lower plate count.

A column with a high number of theoretical plates will have a narrower peak at a given retention time than a column with a lower N number.

Here we observe a very broad peak only.

No any other information like RT, and height etc so plate height cannot be compare based on informative value.

2 ] Another parameters are used to measure a column’s efficiency

The two parameters are related by the following equation:

N= L/H

Where N = Number of theoretical Plate

L= L is the length of the column packing (usually in cm this is a constant for a given column)

H = Plate height

So Length of column packing and Number of theoretical Plate we don’t know

Here this information is not mention hence option D is correct

Q 2] Which compound have greater partition coefficient?

Answer

Justification: To determination of partition coefficient we must need concentration of solute in the stationary phase (Cs) and concentration of the solute in the mobile phase (Cm)

K = Cs / Cm

Here this information is not mention hence option D is correct

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.