Optimal Template Removal from Molecularly Imprinted Polymers by Pressurized Hot Water Extraction

Abstract

An optimal extraction method for the removal of templates from molecularly imprinted polymers (MIPs) is presented. The extraction method is based on pressurized hot water extraction (PHWE). PHWE was evaluated by application to three distinctly colored MIPs for chlorophyll (green), quercetin (yellow) and phthalocynine (dark blue) with subsequent monitoring of template removal and template bleeding by an ultraviolet spectrophotometer. The templates were washed-off and the extraction efficiency (EE) was compared to that of soxhlet and ultrasonic extraction methods. PHWE employed hot water at an optimal temperature of 220°C, pressure of 50 bars and flow rate of 2 mL min -1 to thoroughly wash-off the respective templates from their MIPs. The EE evaluated for PHWE was over 99.6% for all the MIPs with no subsequent or minimal template bleeding (\0.01%). The washing procedure was simple and relatively fast as it was achieved in 70 min at the most. At 95% confidence level (n = 3), soxhlet and ultrasonic recorded EE that was not significantly different (\94.5% in all cases) from that of PHWE ([99.6% in all cases). Soxhlet and ultrasonic had washing procedures that were slower (over 18 h) and employed large quantities (400 mL) of organic solvents modified with acids. The percentage relative standard deviations (%RSD) for the EE and recovery results were less than 2.3% in all cases indicating the high reproducibility of the method. Overall, the three methods performed comparably in extracting templates. PHWE seems to be the method of choice as it employed water which poses no environmental threat.

Development of an aflatoxin B1 specific molecularly imprinted solid phase extraction sorbent for the selective pre-concentration of toxic aflatoxin B1 from child weaning food, Tsabana

“…Therefore, in future work it will be necessary to develop a multi-aflatoxin templated MIP which can simultaneously pre-concentrate all the main aflatoxins in complex matrices at very low concentrations, rather than individually pre-concentrating a single aflatoxin. Because the potent nature of the aflatoxin B1 template was a challenge during MIP synthesis, in future work a non-toxic mimic template known as a 'dummy' would be useful [30]. Other than the safety advantage, the 'dummy' would also be beneficial because the structure would differ from the target analyte.…”

Sensors Based on Molecularly Imprinted Polymers

“…The process of template removal is not essentially elaborate and not based on expensive reagents, contrary template removal can be accomplished by a simple solvent like water when the procedure is wisely made. Batlokwa and coworkers described a method using pressurized hot water extractions [74]. They fabricated MIPs from a copolymer prepared from methacrylic acid and ethylene glycol methacrylate with imprinted chlorophyll, quercetin and/or phthalocyanine.…”

Bio-Mimetic Sensors Based on Molecularly Imprinted Membranes

“…Later, Lulinski et al [ 66 ] obtained a low level of template bleeding from a dopamine-imprinted polymer applying a Soxhlet extraction followed by a microwave-assisted extraction. More recently, other studies were performed to optimize the template removal from molecularly imprinted polymers [ 64 , 67 ].…”