By rashmi nair on Thursday, June 17, 2004 - 03:41 am:
It was observed during HPLC analysis of some products that the retention time varies as a function of concentration.For a perticular conentration the retention time remains the same but when the concentration changes the retention the changes by a significant factor.
Are there any literature available that speak about this observation
By Anonymous on Thursday, June 17, 2004 - 10:11 am:
perhaps change in peak shape will give you a slight difference in peak-max
By Anonymous on Thursday, June 17, 2004 - 02:29 pm:
A few questions.
How much change in the retention time?
How close to the target concentration do you have to be to get a consistent retention time?
Does the retention time change for both increases and decreases in concentration?
By rashmi on Friday, June 18, 2004 - 03:20 am:
RT(min) Conc.(µg/mL)
11.3 7.5
11.5 75
11.9 1500
Retention time always decreases with decrease in concentration.Also the peak shows tailing.An overlay of different concentration is acurate ,ie the higher concentration peak start and peak end always covers the lower concentration
By rashmi on Friday, June 18, 2004 - 04:45 am:
RT(min) /Conc.(µg/mL)
11.3 / 7.5
11.5 / 75
11.9 / 1500
By Anonymous on Friday, June 18, 2004 - 06:51 am:
I think that the first responder probably had it right in that the changes in concentration are causing changes in peak shape. Especially if the peak onset is starting at about the same time.
By henrik on Friday, June 18, 2004 - 07:53 am:
If it should be caused by the peak shape, you could try to speed op the sample frequens. Normaly 20 datapoint over the peak
By Anonymous on Sunday, June 20, 2004 - 06:48 pm:
You need to give much more explanation to get to the details of the changes that you are observing. Is the sample ionic? Do you use a buffer? Which buffer? What concentration? What is the pH? What is the pK of your analyte? What is the sample dissolved in? If it is a potentially ionic sample, what is the counterion? ...ETC...