A new doctoral thesis at Karlstad University provides increased understanding of how medicines can be analysed more reliably and safely. The research focuses on fundamental investigations of liquid chromatography, one of the most important analytical techniques used in the pharmaceutical industry. This type of fundamental understanding is essential, as many current challenges cannot be solved by empirical method optimisation alone.

Liquid chromatography is used to separate and measure the different components of a medicine. In addition to the active substance, medicines often contain excipients that stabilise the product and determine its final form. To establish the correct dosage and detect harmful substances, the active ingredient must first be separated from these other components.

“Charged molecules are generally more difficult to analyse than uncharged molecules in liquid chromatography. While many traditional drugs carry a single charge, newer therapeutics such as oligonucleotides and peptides often carry multiple charges, making their analysis significantly more challenging,” says Abdul Haseeb, Doctor of Analytical Chemistry and author of the thesis Fundamental Investigations of Retention and Adsorption in LC with Emphasis on Charged Solutes.

Challenging molecules

During liquid chromatographic analysis, charged drug molecules exhibit more complex interactions with the stationary phases than uncharged compounds. This can lead to problems such as peak tailing, low retention, and limited separation. In practice, this may mean that degradation products or impurities are not separated from the active ingredients, which in turn can affect the safety and effectiveness of medicines.

One unexpected finding of the research is that so-called active sites (residual silanols) in stationary phases, which are traditionally considered a main source of peak tailing, can actually improve peak shapes when properly controlled. “Rather than removing these sites through extensive chemical modifications, they can be utilised directly to enhance separation efficiency and simplify column design,” says Abdul Haseeb.

Important for future medicines

The research is particularly relevant for new types of medicines, such as oligonucleotides and peptides, which are used to treat genetic and previously hard‑to‑treat diseases. These are large molecules with multiple charges and place very high demands on purity and analytical characterization.

“Our work shows that a deeper mechanistic understanding of chromatographic processes is necessary to develop robust analytical methods for modern medicines. This is crucial for ensuring that new types of medicines can be accurately analysed, used safely by patients, and approved by regulatory authorities,” says Abdul Haseeb.