Teboho Mpakanyane , a former Master’s student in Chemistry at the National University of Lesotho (NUL) and now a PhD student under Distinguished Prof. Nyokong’s supervision at Rhodes University in South Africa, just created an amazing material! The material can measure the amount of a harmful chemical called 4-hydroxybenzoic acid (pHBA) in water and in the environment.
Mpakanyane’s sensor is capable of detecting pHBA at an amazingly low amount (concentration) of 1.18 micromolar— that has never been reported before!
His work titled, “The Novel Cobalt (II)-Porphyrin/Fe₂O₃-Reduced Graphene Oxide Nanohybrid for Enhanced Electrochemical Sensing of 4-Hydroxybenzoic Acid” was published in the prestigious journal Electrocatalysis; https://link.springer.com/article/10.1007/s12678-025-00944-8
But let’s start from the beginning.
When parabens, which are preservatives used in lotions, food, and even medicine, break down, they form pHBA. This chemical finds its way into rivers and soil, where it can harm plants, animals, and even people. Scientists have linked it to certain health problems, like breast cancer.
For years, scientists have struggled to detect pHBA quickly and at low cost.
That’s where Mr Mpakanyane’s research comes in.
“I wanted to create a material that could detect pHBA faster, cheaper, and with more accuracy,” he said.
So, what did he do?
He combined three powerful materials: cobalt (II)-tetra aminophenyl porphyrin (CoTAPor), iron oxide nanoparticles (Fe₂O₃), and reduced graphene oxide (rGO). He then placed this unique mixture on a glassy carbon electrode to create a sensor that could detect even the smallest amounts of pHBA.
The secret?
“When these materials work together, they create something extraordinary,” he explains. “The sensor generates an electric signal when it comes into contact with pHBA. The stronger the signal, the higher the amount (concentration) of the chemical.”
But why is this a big deal?
In the past, scientists used methods like high-performance liquid chromatography to detect pHBA. These methods are slow, expensive, and require a lot of preparation. Mr Mpakanyane’s sensor is faster, does on-site testing, and it is more environmentally friendly.
“With this sensor, we can monitor pollution as it happens and act before it’s too late,” he says.
Getting here wasn’t easy.
On their own, CoTAPor, Fe₂O₃, and rGO aren’t very effective. But Mpakanyane figured out how to make them work together.
“It’s like putting together a perfect team,” he says with a smile. “Each material brings something unique, and together they create something powerful.”
To test how well his sensor works, he conducted a series of experiments using a technique called Cyclic Voltammetry. This method involves applying an electric current to the sensor while it’s exposed to different concentrations of pHBA. The sensor produced a clear and strong electric signal that increased as the concentration of pHBA went up.
This proved that the sensor could accurately measure the amount of pHBA present in the sample. In fact, the sensor outperformed traditional methods by being more sensitive and detecting pHBA at extremely low levels.
In addition to cyclic voltammetry, he also used another technique called Chronoamperometry, which measures the electric current over time.
This helped confirm the sensor’s stability and reliability. The results showed that the CoTAPor-Fe₂O₃-rGO sensor not only detected pHBA faster but also remained stable after multiple tests.
With a detection limit as low as 1.18 micromolar, this sensor is now one of the most advanced tools for keeping an eye on environmental pollution and protecting water sources.
He’s working on making the sensor even better and finding ways to use it to detect other harmful chemicals. In the future, he hopes these nanomaterials could also be used in healthcare, pharmaceutical and/ industrial levels.
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Visit Milco, a store that sells only made in Lesotho products at Sefika Complex! It was founded by the NUL Innovation Hub!
