Molecularly imprinted polymer-assisted sample clean-up of ochratoxin A from red wine: merits and limitations.
A new analytical method for the determination of the carcinogenic mycotoxin ochratoxin A (OTA) in red wines has been developed involving a two-dimensional solid-phase extraction (SPE) clean-up protocol on C18-silica and a target-selective molecularly imprinted polymer (MIP). Prior removal of the interfering acidic matrix compounds by C18 solid-phase extraction was crucial for a successful clean-up as direct sample loading onto the MIP led to poor recoveries. The combined solid-phase extraction protocol afforded extracts suitable for sensitive ochratoxin A quantification by HPLC-fluorescence detection. Preliminary validation of the method performance with spiked (0.033-1.0 ng OTA/ml) and commercial red wines provided recoveries >90% and < 10%, with limit of detection (LOD) and limit of quantification (LOQ) of 0.01 and 0.033 ng/ml. However, a similarly favorable performance characteristics was observed in control experiments in which the MIP was replaced by the corresponding non-imprinted polymer (NIP). These findings provide evidence that under the employed experimental conditions specific analyte binding to imprinted binding sites plays a minor role in selective OTA retention. In the framework of this study, other problems inherent to MIP-based solid-phase extraction have been addressed. These include the reproducible preparation of MIP materials with consistent molecular recognition characteristics, the potential for repeated use of MIP, unfavorable polymer swelling in application-relevant solvents, potential sample contamination by template bleeding, and slow analyte binding kinetics.
Maier
Norbert M
NM
Institute of Analytical Chemistry, University of Vienna, Währingerstrasse 38, A-1090 Vienna, Austria. norbert.maier@univie.ac.at
Buttinger
Gerhard
G
Welhartizki
Silvia
S
Gavioli
Elena
E
Lindner
Wolfgang
W
D002851:Chromatography, High Pressure Liquid; D009183:Mycotoxins / Q000737:chemistry / Q000302:isolation & purification*; D009793:Ochratoxins / Q000737:chemistry / Q000302:isolation & purification*; D011108:Polymers / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence; D014920:Wine / Q000032:analysis*
D009183:Mycotoxins; D009793:Ochratoxins; D011108:Polymers; C025589:ochratoxin A