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Using Cogent™ Retention Maps

On this website are unique, “Retention Maps” for neutral, acid and basic organic target compounds at three different pH’s (2.18, 6.80 & 8.00).

What is a Retention Map and how does it help chromatographers in practical method development?

A retention Map is a graph of the retention time of compounds separated on an HPLC column plotting changes in % B (organic in ARP or ANP as most polar solvent if ONP) against retention time. The flow rate and column size will be specified on each Retention Map, but interpolation of different column sizes or flow rates are simple. For example, if a 75 x 4.6 column is shown in the map, multiply the time scale by a factor of 2 for 150 x 4.6. Similarly if a flow of 3 ml/min is shown on the map, divide time scale by 3 for 1 ml/min. Combine flow and size as appropriate for your needs. To simplify interpretation, we have plotted the raw data as simple Retention Maps and not as log plots.

To use a Retention Map, classify your compound as an acid, base or neutral and compare to respective Retention Map for the same class of compounds.

Now compare the log P (Octanol:Water Partition Coefficient) of your sample (these are available on a limited basis or can be calculated for you from a known structure from the free web site http://www.syrres.com/esc/est_kowdemo.htm) to the target compounds shown.

There is a very considerable probability that your appropriate solvent composition and anticipated retention profile of time compared to % B can be easily extrapolated from the Retention Map irrespective if is an ARP/ANP or ONP. This will give you a lot of information that is very helpful in cutting down time to develop methods. Some of the information that it provides is where two compounds will co-elute or separate on the same compound. This can be very helpful in determining if you will need a gradient for separation of your compounds. For assistance with understanding Using Retention Maps, inquire for more information or contact our technical department for assistance. 1-732-578-1777 ext. 5#.

If you are using basic compounds be aware that it may be simple ANP or ARP plot, like pyridine depending on pH / acetonitrile %, or give an U or V plot like the antidepressants ( which are combinations of ARP below critical % acetonitrile and ANP above critical % acetonitrile).

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