BPA is one of the highest-volume industrial chemicals on the planet and the building block of polycarbonate plastics and epoxy resins. It lines food and beverage cans, coats water pipes, and forms part of thermal paper receipts, which means human exposure is effectively continuous. The concern is not acute poisoning but endocrine disruption: BPA mimics estrogenic hormones at very low concentrations, and systematic reviews have linked chronic exposure to metabolic disorders, reproductive dysfunction and other health effects. In 2023, the European Food Safety Authority re-evaluated the risks of BPA in foodstuffs and dramatically tightened its tolerable daily intake, underscoring how seriously regulators now treat this ubiquitous compound. Because BPA leaches from containers and products into water systems, environmental monitoring demands methods that can detect it at parts-per-trillion levels, not merely parts per billion.

The analytical challenge is twofold. First, real environmental samples are messy: BPA coexists with phenolic relatives, dissolved organic matter and salts that can swamp a detector. Second, the gold-standard instruments for trace BPA analysis, such as liquid chromatography coupled to mass spectrometry, are expensive, require skilled operators and are often unavailable in the laboratories of developing regions where water quality problems are most acute. Spectrophotometry, by contrast, is cheap, robust and found in nearly every teaching and municipal lab, but on its own it lacks the selectivity and sensitivity to pick a single endocrine disruptor out of a complex matrix. The new study addresses both problems at once by pairing a highly selective extraction material with an affordable optical readout.

The heart of the method is molecular imprinting, sometimes described as building a plastic mold around a molecule. The researchers polymerized functional monomers in the presence of BPA itself, so that as the polymer network hardened, cavities formed that were complementary to the template in size, shape and chemical functionality. After the template was leached out, the polymer was left with recognition sites that preferentially rebind BPA over structurally similar compounds, behaving like artificial antibodies but with far greater chemical and thermal stability. The team chose a core-shell architecture: a solid core provides mechanical integrity and a large surface area, while a thin imprinted shell places the recognition cavities close to the surface, where analyte molecules can reach them quickly rather than diffusing through a dense polymer bulk.

Synthesis proceeded by co-precipitation polymerization, a straightforward route that avoids elaborate equipment and yields particles suitable for packing into extraction cartridges. The material was characterized with Fourier-transform infrared spectroscopy, which confirmed the functional groups responsible for binding, and field-emission scanning electron microscopy, which revealed the morphology of the imprinted particles. UV/Vis spectroscopy served both to track template removal and, ultimately, to quantify BPA after extraction. The simplicity of this characterization and workflow is part of the appeal: the entire pipeline from sample to number can run on instruments that cost a small fraction of a mass spectrometer.

Performance optimization followed the classic levers of adsorption chemistry. The researchers systematically varied pH, contact time, adsorbent dose and shaking speed to maximize uptake. The optimum emerged at pH 6, close to the neutral conditions of most natural waters, which is convenient for direct application to real samples. Under these conditions the polymer reached a maximum adsorption capacity of 112.35 milligrams of BPA per gram of material, a figure that reflects both the density of imprinted cavities and the accessibility afforded by the core-shell geometry. Kinetic analysis showed that adsorption follows a pseudo-second-order model, meaning the rate-limiting step is the chemical interaction between BPA and its binding sites rather than simple diffusion, while equilibrium data fit the Langmuir isotherm, indicating uniform, monolayer-type binding onto a finite set of equivalent sites.

The selectivity results are perhaps the most striking. When the polymer was challenged with coexisting molecules that resemble BPA, the relative selectivity factors came out below one, confirming that the imprinted cavities genuinely discriminate in favor of their template. This matters enormously in practice, because environmental waters contain bisphenol analogs and phenolic compounds whose signals would otherwise interfere. The calibration curve was linear across 2 to 10 micrograms per liter after preconcentration by solid-phase extraction, and the limits of detection and quantification were 0.98 nanograms per liter and 329.5 nanograms per liter respectively. Those numbers mean the method can confidently flag BPA at concentrations relevant to regulatory and toxicological thresholds, using an optical detector rather than a mass spectrometer.

To prove the method works outside the laboratory, the team applied it to real environmental samples, and the technique performed successfully, recovering BPA from the complex matrices that typically defeat less selective adsorbents. The combination of a selective imprinted polymer, a simple solid-phase extraction step and conventional spectrophotometric detection creates a workflow that municipal water utilities, university teaching labs and field stations in resource-limited settings could realistically adopt. It also aligns with a broader movement in separation science toward greener, more affordable analytical chemistry, in which molecularly imprinted materials are increasingly promoted as sustainable alternatives to solvent-intensive extractions and instrument-heavy confirmatory methods.

The work also fits into a fast-growing literature on core-shell imprinted particles, which have been used for everything from extracting BPA from milk to sensing proteins and detecting veterinary drug residues. By keeping the imprinted layer thin, the core-shell design solves the chronic weakness of conventional bulk-imprinted polymers, in which many recognition sites are buried so deep that analytes cannot reach them, wasting capacity and slowing equilibration. The new study demonstrates that a facile co-precipitation synthesis, rather than a complex multistep fabrication, is enough to capture those benefits for environmental monitoring.

For the public, the significance is straightforward: the plastics that make modern life convenient shed a hormone-mimicking chemical into water at concentrations that are difficult to measure but increasingly regulated. Tools like this core-shell imprinted polymer make it possible for far more laboratories to find out exactly how much BPA is in a river, a reservoir or a tap, at a fraction of the usual cost. If such methods spread, the data they generate could sharpen exposure assessments, support enforcement of tightened safety limits, and ultimately push manufacturers toward safer alternatives. The study, published in Polymer Bulletin, shows that sometimes the path to ultrasensitive detection is not a more expensive instrument but a smarter piece of plastic designed to recognize a single molecule.

Subject of Research: Development of a core-shell molecularly imprinted polymer for ultrasensitive solid-phase extraction and spectrophotometric detection of bisphenol-A in environmental samples

Article Title: High-performance core-shell designed molecularly imprinted polymer solid-phase extraction for ultrasensitive spectrophotometric monitoring of bisphenol-A

Article References: Jagirani, M. S., Balouch, A., Jagirani, I., & Khuhawar, A. H. (2026). High-performance core-shell designed molecularly imprinted polymer solid-phase extraction for ultrasensitive spectrophotometric monitoring of bisphenol-A. Polymer Bulletin, 83(11), Article 635. https://doi.org/10.1007/s00289-026-06686-x

Image Credits: AI Generated

DOI: 10.1007/s00289-026-06686-x

Keywords: bisphenol-A, molecularly imprinted polymer, core-shell, solid-phase extraction, spectrophotometry, endocrine disruptor, water analysis, adsorption, Langmuir isotherm, environmental monitoring, co-precipitation polymerization, UV/Vis spectroscopy