Each of the six materials was analysed in triplicate. In addition, aliquots of the three blank materials were spiked at two levels (0.1 ng/g, o.3ng/g) and analysed in triplicate. thelatter experiments served to establish the process recovery of SEA (overall recovery which comprises losses during extraction (extraction recovery) as well as influences from the ELISA analysis(calibration, but also potential matrix effects))