Hot On Heels Of Fake Drugs

The first thing that catches the eye is the safe. It's not a discreetly built-in model like those found in hotel rooms; instead, it juts out from the wall above the desk, beige and bulky. Indeed, this equipment is special for an office in ETH's HCI building-but so is its owner's field of research, as the safe's contents reveal. That's where Dr. Christian Steuer, pharmacist and pharmaceutical scientist, keeps the sensitive samples for his analyses under lock and key.

"One of our main research interests is figuring out how we can quickly and reliably test the composition and purity of certain substances," explains Steuer. "These may be historical samples-for example, opium that is a hundred years old or contemporary products. Medicines, including cannabis, peptide-based preparations, and essential oils, are often adulterated and/or sold online as natural alternatives without proper labeling, sometimes with serious health consequences for consumers." We want our research to contribute to drug safety."

With an almost detective‑like approach, his group uses its expertise to uncover even the most sophisticated counterfeits. "As analysts, we are also craftspeople," Steuer explains. "Depending on the research question, we choose the tools that fit best. Sometimes we tinker with instruments, adjusting them to detect the tiniest amounts of molecules. Our goal is to develop fast methods that deliver maximum information and reliable results."

The rose oil case

His openness to a wide variety of research topics and the prospect of being able to freely experiment with methods were among the reasons why, 10 years ago, Christian Steuer decided to leave his valued but strictly regulated position as a laboratory analyst at the Aarau Cantonal Hospital to pursue research at ETH.

Since then, he and his team have been investigating problems such as how to test essential oils quickly, easily, and reliably. "Essential oils are very important for the fragrance, food, and pharmaceutical industry, but they are expensive. Rose oil, in particular, is quite costly," says Steuer, "it takes over four tons of rose petals to produce one liter of pure oil. Adulterated versions are therefore lucrative, and current quality control methods are very slow."

The Steuer's Group tested several methods and discovered that a combination of infrared spectroscopy and a specific type of mass spectrometry enables an analysis of the oil that is just as accurate but much faster than standard gas chromatography "By combining this with chemometric methods for data analysis, we were able to drastically reduce analysis times. Together with a doctoral student, we successfully developed and published this model ( Raeber and Steuer 2023 ). As a teacher, it's wonderful to see how students grow through their project," says Christian Steuer happily.

The Ozempic case

In the laboratory of the Saarland-born researcher, products are analyzed not only for small molecules, but also for large ones, such as peptides (short chains of up to 100 amino acids). This "other research arm", as Steuer calls it, stems from his postdoctoral work, during which he studied GLP-1 receptor agonists such as Ozempic. "Peptides are fascinating because they require a different toolkit-in this case, liquid chromatography-and because they are increasingly important as pharmaceuticals. So standard procedures for quality assurance are needed here as well," Steuer emphasizes.

"Take Ozempic, for example. Following the global success of the weight-loss injection, a trend is emerging, particularly in the U.S., toward the use of peptides in the wellness and sports nutrition sectors. In some cases, consumers obtain these peptides from the black market or the chemical market to circumvent legal regulations and the associated analytical requirements for pharmaceutical substances. In preparations that have not undergone quality control, we often observe certain modifications-presumably due to improper storage conditions or incorrect synthesis strategies-which negatively impact the drug's efficacy and safety."

Indeed, in 2026, the Steuer Group demonstrated how rapid problematic peptide modifications can occur ( Erckes et al 2026 ): e.g., the conversion of an amide group into an acid (deamidation) or a structural change in the peptide chain (isoaspartate). The team presented tandem mass spectrometry as the best method for detection. This method not only measures the parent molecule but also, in a subsequent step, its individual fragments. The method does not save the batch, but at least helps to withdraw it from circulation.

The crux with trifluoroacetic acid

Another challenge in peptide synthesis is the use of the standard reagent trifluoroacetic acid (TFA). Often, insufficient attention is paid to how much of it remains in the final peptides. This reagent is not only potentially harmful to health but also environmentally problematic.

Steuer and his team developed a standardized method for replacing TFA with chlorides ( Erckes et al. 2025 ). This approach does not affect the peptides. "Our solution works, but we see it only as a stopgap. Eventually, TFA will no longer be necessary," Steuer hopes, "which would certainly be better for the environment."

A new hot lead

Speaking of nature: Christian Steuer also enjoys being outside -whether spending time with his family or heading out for a run. In his office, meanwhile, not far from the safe, several chili plants are happily sprawling in all directions. The peptides in these plants have inspired Steuer's latest project idea and may soon lead the team down a new hot and, indeed, spicy trail. Where it will lead eventually is still unclear, but that doesn't bother the newly appointed lecturer at D-CHAB: "With enthusiasm, persistence, and ambition, anything is possible in life."