Table 2.
Sample weight (g), solvent volumes (mL), dispersing and swirl times (s), and expected times for phase separation for various samples of animal origin.
| Extraction step | Egg | Egg powder | Fat | Fish | Fish oil 6 | Liver | Meat | Milk | Milk powder 7 | Milk fat, butter | Infant food | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. extraction | Sample weight (g) 1 | 10 | 2.4 4 | 1.0 | 10 | 1.0 | 10 | 15 | 30 | 5.0 | 1.0 | 20 |
| Propan-2-ol (mL) 2 | 32 | 32 | 32 | 32 | 32 | 32 | 48 | 32 | 16 | 32 | 32 | |
| Cyclohexane (mL) | 40 | 40 | 40 | 40 | 40 | 40 | 60 | 40 | 20 | 40 | 40 | |
| Ultra-Turrax A (s) | 10 | 10 | 20 | 10 | 10 | 10 | 20 | 10 | 10 | 10 | 10 | |
| ddH2O (mL) | 24 | 24 | 24 | 24 | 24 | 24 | 36 | 22 | 16 | 24 | 24 | |
| Ultra-Turrax B (s) | 15 | 15 | 30 | 15 | 15 | 15 | 30 | 15 | 15 | 15 | 15 | |
| Propan-2-ol (mL) 3 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | - | 5 – 10 | 5 – 10 | |
| Circular swirling (s) | 5 – 10 | 5 – 10 | 5 – 10 | 15 – 20 5 | 5 – 10 | 15 – 20 5 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | |
| Phase separation (s) | < 30 | < 30 | < 30 | 2 – 3 min | < 30 | 2 – 3 min | < 30 | < 30 | < 30 | < 30 | < 30 | |
| 2.−3.(4.) extraction | Repetitions: | 2 | 2 | 2 | 2 – 3 | 1 | 2 – 3 | 2 | 2 | 2 | 2 | 2 |
| Cyclohexane (mL) | 20 | 20 | 20 | 20 | 20 | 20 | 30 | 20 | 14 | 20 | 20 | |
| Ultra-Turrax (s) | 10 | 10 | 15 | 10 | 10 | 10 | 15 | 10 | 10 | 10 | 10 | |
| Propan-2-ol (mL) 3 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | - 8 | 5 – 10 | 5 – 10 | |
| Circular swirling (s) | 5 | 5 | 5 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | 5 – 10 | |
| Phase separation (s) | < 30 | < 30 | < 30 | 1 – 2 min | < 30 | 1 – 2 min | < 30 | < 30 | < 30 | < 30 | < 30 | |
Example weight, adjust solvent volumes for other sample weights. For sample weights (except fat) < 5 g use volumes as calculated for 5 g.
Before adding cyclohexane, mix sample with propan-2-ol by gentle swirling.
Rinse sample remains sticking to the dispersing element back into sample vessel with propan-2-ol (enlarge volume to 10 mL if required).
Egg powder (dried): soak in 7.6 mL ddH2O (for 76% water content) prior to extraction.
If, in rare cases, an organic phase (≥ 10 mL) does not separate at the top of the mixture by (repeated) swirling, alternatively the mixture can be centrifuged.
Extraction is advised only if clean extracts are required for follow-up ultra-trace analysis of POPs.
Whole milk powder. Adjust sample weight and volumes for semi-skimmed or skimmed milk powders.
Use 7–10 mL cyclohexane to rinse sample remains sticking to the dispersing element into sample vessel, then add 2–3 mL propan-2-ol for phase separation.