During conversations with chromatographers I am frequently asked, “How easy is it to transfer a method between different liquid chromatography instruments?” My usual answer is, “It depends.” Before I explain why I say, “It depends,” let’s go over a brief definition of the term “method transfer” so we’re on the same page.
In scientific literature, the term “method transfer” is often used when a method is transferred between columns, often accelerated from a standard HPLC column with > 3 µm particles in a 4.6 mm inner diameter column format to a UHPLC column with sub 2 µm particle sizes. While this is the generally accepted definition of “method transfer” this is not what I intend for this blog post or pharmaceutical laboratories to consider method transfer to be.
In pharmaceutical laboratories, however, formal method transfer is needed when one particular method, likely already validated, is transferred from one lab to another (e.g. to a quality control lab or any contract lab.) In this scenario, the column characteristics need to remain identical during the method transfer while the HPLC instrument might change during this process depending on the equipment of the receiving laboratory.
Now that we’ve clarified, what are the main parameters influencing the difficulty of method transfer when non-identical HPLC instruments are involved? These are mainly gradient delay volume, pre-column volume, post-column volume, eluent pre-heating and column thermost.... In order to better visualize these influences, I have estimated the importance of these parameters in the radar plots below where the further the data point is from the center of the graph the more important the parameter is under those conditions.
From these radar plots, it is clear that the transfer of an HPLC method is easier than the transfer of a UHPLC method because the relative effect of these selected parameters is less prominent than what is required in UHPLC method transfer. While these plots show that transferring HPLC methods are easier than transferring UHPLC methods in theory, I believe many of us already have noticed this in practice. From experience, we know that it is not that easy to just run a UHPLC method on a standard HPLC instrument (if the max pressure permits) without considerable adjustments. Some of the reasons why this is more difficult are mostly due to different gradient delay volumes and pre- and post-column dispersion volumes. However, transferring a standard HPLC method between HPLC instruments can be quite straight forward if you have the right tools available.
Custom injection program to solve any issues resulting from uneven pre-column volume. This can be the case if the original system has significantly higher pre-column dispersion volume and the sample is dissolved on strong organic solvents (stronger than the starting eluent conditions)
Multiple column thermostatting modes as well as column pre-heating options to mimic the conditions of your originator systems
Various detector flow cells to match post-column volume
As such method transfers are frequently conducted in regulated environments it is important to consider the adherence to regulatory guidelines. In this respect, the Vanquish Core HPLC system is qualified for both high and low gradient delay volume flow paths. Changes of any gradient delay volume, as well as thermostatting mode or eluent pre-heating, are simply conducted in the instrument method file and visible to any auditor in the audit trail. Such an approach is clearly permitted by regulatory guidelines (The United States Pharmacopeial Convention, United States Pharmacopeia 41) and does not alter any gradient table.
All the features packed into the Vanquish Core makes method transfer of HPLC methods pretty #simpletothecore.