Chromatography Forum

I am having some trouble figuring out these. Any help would be appreciated

1) Under the preeceding conditions, hoiw could the plate height be reduced by one third? What would happen to the optimal velocity (Uopt) under these conditions? what would happen to the number of theoretical plates N for the same length of column

H=B/u +Cu


2) For the above how can you maintain the same # of theoretical plates while reducing plate height by 1/3

3) The preceding assumes that all band broadening occurs within the column. Name 2 sources of extracolumn band broadening that might also contribute to the overall width of HPLC peaks

Looks like someone is posting their homework on the forum.

If I answer these questions I demand 5% of your salary in your third year of employment.
On second thought, if you don't figure this out on your own that'll only be $500

Look bro,

If you think that these forums are full of "so called smart people" why you posted your questions here in the first place, ha?

Take it easy. Take it slow

I am having some trouble figuring out these. Any help would be appreciated

1) Under the preeceding conditions, hoiw could the plate height be reduced by one third? What would happen to the optimal velocity (Uopt) under these conditions? what would happen to the number of theoretical plates N for the same length of column

H=B/u +Cu


2) For the above how can you maintain the same # of theoretical plates while reducing plate height by 1/3

3) The preceding assumes that all band broadening occurs within the column. Name 2 sources of extracolumn band broadening that might also contribute to the overall width of HPLC peaks

We could but personally, for part one, I am not psychic and don't Know what the "preceding conditions" are so will leave that part well alone. the other parts can be found by a little light reading of something called "Texbooks" or a little googling

JGK I provided the equation H=B/u + Cu. This is the preceding/prior info. If someone really knew how to do this question they would have suggested I make use of it rather than wasting their time responding foolishly.

Secondly, question e and f requires some mathematical skills which some peopel that responded seem to lack

Ciprofloxacin,

I am sure that all the senior posters know the answer, but people here get irritated if someone just posts their homework to be answered without any effort from them to solve it (maybe because we didn't have internet and discussion forums when we had to do our homework). I suggest that Tom adds a sticky in the student projects that we can refer in the future (i.e. under which conditions we will reply on "homework" questions) that going back and forth with the student posters which can lead to start insulting each other.

I won't answer your questions directly but I'll give you some tips:

H=N/L
u=L/to
Think how particle size affects plate height and theoretical plates...

Dear Ciprofloxacin:
The original form of the equation for height-equiv. of theoretical plate is:
H = A + B.u + C/u (A,B,C are constants).
Perhaps the "condition" is that the A-term is negligible?
Alfred