Extraction methods
For use in the QuEChERS optimisation studies, a control MRS broth (10 mL) was fortified at a concentration of 3 µg/mL, from the 15 standard mix solution (100 ppm; Section 2.2), mechanically shaken for 15 min. The following extraction methods were examined by direct injection (post-culture filtration) [23]; SPE [20]; LLE [18] and with the newly developed QuEChERS method.