Waters ACQUITY Premier Columns: A New Solution for Sample Loss of Metal-Sensitive Analytes

Why do we lose compounds while trying to measure them? Are they disappearing? Are they breaking down? Why and how?

It all starts with adsorption and for certain metal-sensitive analytes, it renders chromatographic analysis using stainless steel columns a significant chore.

Thankfully, Waters engineers have created an elegant solution to this widely experienced, yet lesser known, problem and it comes in the form of new ACQUITY Premier Columns with MaxPeak High Performance Surface (HPS) technology.

More on these new columns in a moment.

Adsorption is a fundamental behavior at the analyte/surface interface. Compounds will adsorb to many different types of surfaces. Some stick strongly. Some free themselves up quickly and are in free exchange with the solution phase. Some stay on the surface for longer stretches of time and might even undergo a reaction that induces a structural change! The driving force of the adsorption and its strength depends on many factors: the analyte itself, the environment, and of course the surface. By changing them, we can modulate adsorption strength to our liking. Actually, chromatography is a great example of when an analyst actively manipulates the strength of adsorption to separate mixtures of compounds. (Think gradient elution.)

However, there’s a long-standing battle in chromatography to get analytes to behave. In one all-too-common case, acidic analytes can be lost in an analysis as a result of electrostatic interactions. Acidic analytes bearing negative charge are attracted to electron-deficient, positively charged metal surfaces. They can bind to such a surface quite strongly, sometimes more strongly than the desired chromatographic interactions, such as the hydrophobic interaction employed in a reversed-phase separation. This adsorption is why acidic analytes frequently ‘disappear’ in a column during chromatographic analysis.

Sometimes, this can be a mere inconvenience. Other times, it can be a serious problem.

Researchers have tried various approaches to deal with this. For example, they have changed the pH and ionic strength of mobile phases, tried to block undesired interactions by adding competing anions, and tested out non-metallic column hardware. These clever applications of chemistry knowledge may occasionally work, but none of them is a universal solution. Changing the pH alters the chemical environment and will thus influence chromatography – which means you might end up needing to redevelop a method. Adding salts or competing anions will also alter the chromatography and limit the use of sensitive MS detection. Lastly, commonly available non-metallic hardware does not have the mechanical strength nor precise manufacturing, that is required for high-efficiency separations using sub-2 µm particles.

That’s why it’s exciting to introduce new Waters ACQUITY Premier Columns featuring MaxPeak HPS. Waters has a strong understanding of material science and continues to apply its expertise to bring innovations in chromatography.

Like with past developments of pH-stable BEH hybrid particles and novel bonded phases, Waters is again breaking the mold with MaxPeak HPS. The novel hybrid organic/inorganic surface of MaxPeak HPS effectively deactivates the metal surfaces in a column from reacting and interacting with metal-sensitive analytes. The new ACQUITY Premier Columns are packed with industry-leading Waters stationary phases in the MaxPeak HPS hardware, so you can continue using your LC methods with the added benefit of not losing analytes. At the end, these new columns will offer you highly reproducible separations without a need for lengthy and often detrimental extra passivation steps before injecting the samples.

Can it be this good? Citing Fermat, ‘I have discovered truly marvelous proofs^* of this, which this margin is too narrow to contain.’ I must defer it to my other colleagues to show you many exciting results. Stay tuned!

* ‘a truly marvelous proof’ in the original letter. Of course, Fermat must have discovered one proof for his famous theorem. We have many.

Erin Chambers is the Vice President, Chemistry, at Waters Corporation

Additional resources:

Blog: Addressing the Mystery of Sample Loss

Blog: In Need of Some Reversed Phase Polar Acid Relief

Blog: Late Nights in the Laboratory

Blog: Where Did My Sample Go?

Learn more about ACQUITY Premier Columns