|On-line solid phase extraction coupled to liquid chromatography using column-switching system for mycotoxin analysis in beer
|Dr Ivona Lhotská
|Prof Dalibor Satinsky
Prof Petr Solich
|Charles University, Faculty of Pharmacy in Hradec Králové, Department of Analytical Chemistry
Abstract Information :
Sample preparation prior to chromatographic separation plays an important role in the
analytical process. To avoid time-consuming and manual handling sample-prep, automated online
techniques such as column-switching HPLC are therefore preferred. Column-switching
chromatographic system hyphenizes extraction and separation step by connecting two columns
by switching valve. After preconcentration and clean-up on extraction column, the flow of
mobile phase is switched and retained compounds are eluted from extraction column to
analytical column where the separation is performed.
Two methods for mycotoxin analysis in beer using on-line SPE-HPLC are going to be presented. First method takes advantage of both extraction and separation on core-shell columns for determination of mycotoxins ochratoxin A and citrinin. The aim of the second study was to further raise selectivity using modern selective sorbent for extraction - molecularly imprinted polymers specific for mycotoxin zearalenone.
In comparison with off-line extraction, the advantages of this on-line coupling are solvent saving, avoiding of errors by manipulation, total analysis is less time-consuming. On the other hand, simultaneous optimization of extraction together with separation step is quite problematic, especially in the case of molecularly imprinted solid phase extraction. Difficulties and possible solutions concerning time programming, compatibility of mobile phases and injection volume will be further presented along with the results from screening of Czech beers. In conclusion, all results were acceptable. Ochratoxin A is very common mycotoxin in beer, 100% samples were positive in low concentration (< 2 µg/L, complies with EU legislation). Citrinin and zearalenone were even less prevalent; zearalenone was under limit of quantification in all samples (LOQ 5 µg/L, legislative limit 20 µg/L).