Chloramphenicol-methyl red

Based on the observation that chloramphenicol (CAP)-imprinted polymer possessed a modest affinity for chloramphenicol-methyl red (CAP-MR), Levi et al. [65] designed an intriguing MIP sensor to monitor the change of CAP in patients blood (Fig. 6). The presence of CAP in blood leads to a competitive displacement of CAP-MR from the imprinted cavities. The displaced composite is subsequently monitored at 460 nm. After optimizing the flow rate and concentration of CAP-MR in acetonitrile mobile phase, the response of this system to CAP, thiamphenicol (TAM), and chloramphenicol diacetate (CAP-DA) was determined (Fig. 7). As observed for CAP, there was a linear correlation over the range 1-1000 pg/mL. However, for CAP-DA almost no appreciable response was achieved, even if it was injected to 1000 pg/mL. As also observed, the value for CAP was about 40% higher than that for TAM at the same concentration. This revealed that CAP could compete more efficiently with the bound CAP-MR than TAM did. Further information showed that this method was adequate for detection below and above the recommended therapeutic range (10-20 pg/mL serum, potentially toxic above 25 pg/mL). 

Optical detection of an antibiotic, chloramphenicol, based on competitive displacement of a chloramphenicol-methyl red conjugate bound to a chloramphenicol-imprinted polymer with free chloramphenicol has been demonstrated [40]. A flow injection system in conjunction with a 10 cm stainless steel column packed with the imprinted polymer and acetonitrile as a carrier solution containing chloramphenicol-methyl red conjugate was constructed. The dye conjugate released by displacement by free chloramphenicol was monitored at 460 nm. The signals were proportional to the concentration of free chloramphenicol injected, and the calibration range of this system included the therapeutic range of a chloramphenicol. This concept of flow displacement systems could be applicable not only for chloramphenicol determination but also for other template molecules. 

The technique is based on the in-column competition for the specific binding sites of the imprinted polymer between the analyte and a less retained marker molecule, resulting in a displacement of this analogue proportional to the amount of analyte introduced in the column. In the case of chloramphenicol, the colored derivative chloramphenicol-methyl red was used as a marker (Aabs 460 nm), for... 

Chloramphenicol (CL) in serum Diethylamino-ethyl methacrylate (DEAEM) Competitive displacement of CL-methyl red dye conjugate from CL-imprinted polymer packed in HPLC column 3 ug/ml Levi et al., 1997... 

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