Question

How could you verify peak identities in a water sample chromatogram?

What would happen if another (unknown) anion had the same (or very similar) retention time as chloride?

and how would you be able to tell them apart?

Answer 1

Ans:- In high performance liquid chromatography (HPLC) very high pressure is used to drive the liquid mobile phase through a column packed wit very small particles. The technique may be used to carry out adsoption or partition chromatography.but the most common form involves partition.

The mobile phase which is a liquid is forced through the column under very high pressure .High pressure a requred as the column contains very small particles (3-10micrometer in diameter). th e solvent would take too long to travel through it ,because of the small size of the particle, The componetns of the mixture are exposed to a very high surface area of mobile and stationary phase and good separation is therefore obtained with much shorter columns than with GLC. The most common detectors measure the absorption of UV radiation or visible light by each component as it emerges from the column.

RETENTION TIMES:-

Defferent components have different retention times. The retention times depend on the relative polarities of the stationary phase and the mobile phase .If the stationary phase is less polar than the mobile phase, the most polar component of the mixture is eluted first as it has greater tendency to dissolve i the mobile phase .

If the retention times of two substances measurd under the same conditions are identical is is likely that these substances are the same .The areas under peaks are proportional to the amount of substance present.