Chloramphenicol sensor based on an in situ imprinted polymer

We have recently developed a liquid-chromatography (LC)-based sensor for the broad-spectrum antibiotic chloramphenicol which relies upon the displacement of a chloramphenicol (CAP) dye conjugate from a molecularly imprinted polymer by the drug. The sensor was immune to interference from various chloramphenicol derivatives and ≈60% as responsive to thiamphenicol (TAM), an almost identical analog. The system showed a linear response to the drug over the 3–1000 μg ml−1 range; it was therefore effective both below and above the therapeutic (10–20 μg/ml−1 serum range, being potentially toxic above 25 μg ml−1). The sensor effectively detected CAP extracted from serum with a 3σ detection limit of ca. 5 μg ml−1. We have further simplified the construction of the sensor by the use of an in-situ imprinting technique wherein the polymer is formed inside an LC column. These columns are far simpler to prepare and, although their characteristics are somewhat different, their performance is comparable with that of the bulk-polymerized materials. The capacity of the columns is significantly less than that of packed columns but their ability to separate TAM and CAP is slightly better. The best of these columns showed a fairly linear response (r2=0.95, n=3) for 0–30 μg ml−1 CAP with a detection limit of ca. 3 μg ml−1. The column also showed a linear (r2=0.96, n=3), although lesser response to TAM over a similar concentration range. As with the bulk-polymerized material, the system showed minimal response to the diacetyl derivative CAP-DA.