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Chop the sample up, freeze over night

Fatty samples in presence of water e.g. Avocado. 5) Add **Q-salt mixture. 6) Shake ~1min. 4) Shake ~1min. 7) Centrifuge. Weigh 5g of sample homogenate Add 6.5 mL water (to reach a total water content of ~10mL) Add 10mL AcN Shake ~1min (vigorously)

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Chop the sample up, freeze over night

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  1. Fatty samples in presence of water e.g. Avocado 5) Add **Q-salt mixture 6) Shake ~1min 4) Shake ~1min 7) Centrifuge • Weigh 5g of sample homogenate • Add 6.5 mL water (to reach a total water content of ~10mL) • Add 10mL AcN • Shake ~1min (vigorously) • Add Q-salt mixture* and shake immediately • Shake ~1min (vigorously) • Centrifuge ~2min @ rpm 3000 • ● (Take aliquot for the determination of acidic analytes). In this case, step 10+11 has to be performed before taking the aliquote. • 8) D-SPE cleanup (shake vigorously 30sec) with • • PSA 25mg /mL extract • • MgSO4 150mg /mL extract • • ***silica-based reversed-phase sorbent • (ODS-, C18-type) 50mg /mL extract • 9) Centrifuge ~1min @ rpm 3000 • 10) Please mind to take exact aliquot volume, this is essential for the final analyte to ISTD ratio • Add ISTD (eg TPP/PCB138/Nicarbazine) • 10µL /mL extract • 12) Adjust pH value with formic acid 5% 10µL /mL extract in AcN • 13) Fill into GC- vials for GC/LC analysis 8) D-SPE with PSA MgSO4 ODS*** 3) Add 10 mL AcN 2) Add 6,5 mL water 9) Centrifuge 1) Weigh *2g or 5g of sample homogenate 10) Take exact aliquot e.g. 5mL 11) Add ISTD Mix homogeneously with dry ice 12) Adjust pH value with formic acid solution Chop the sample up, freeze over night http://www.cvua-stuttgart.de *in order to have most non polar pesticides (HCB, DDE, pp-) in scope, the total amount of lipids have to be lower than 0.4g/10mL AcN. **MgSO4 4g NaCl 1g Na2Citrat Sequihydrat 0.5g Na3Citrat Dihydrat 1g ***The removal of the residual lipids can also be achieved when freezing-out the extract for at least 90 or 20 min in the freezer (-18 /-75°C) followed by filteration through cotton wool (where possible just centrifuge and/or decant the extract). Additionally D-SPE is recommended.

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