When meeting with distillation specialists, Dr Jalil Belkamel, a Moroccan aromatherapist who is a specialist in plant extractions, and also Philippe Bertrand, a consultant on plant extraction processes, we clearly noticed their reluctance about the use of a hosepipe (used for in bathroom showers) because the internal surface is covered with rubber which is probably non-food grade. With a high temperature, the rubber deteriorates, solidifies and cracks. In this way, particles from this rubber could pollute the oils.
Fig. 20: Cracks formed in the rubber Fig. 21: Inside the hosepipe
We immediately decided to sacrifice one of these hoses to analyze its composition.
Firstly, the inside of the hosepipe did seem to be made of rubber. The problem is the rubbers used are synthetic and so they probably comprise some compounds added during the synthesis such as phthalates or other molecules to increase their flexibility or their lifetime.
Fig. 22: Skeletal formula of a phthalate
Hypothesis: The oils contain impurities because of the rubber
Experiment: To check for potential impurities in the distilled waters, we decided to do 3 extractions on distillates obtained using 3 different hosepipes (made of 3 different materials) having the same diameter (10mm) and under the same distillation conditions (same heating power from a gas burner, same plants (dry rosemary) and same volume of perfumed waters obtained). The pipes were:
-Multilayer food-grade hosepipe made of several layers of polyethylene;
We analyzed the floating oils by GC, but this time, we did it more slowly and followed it by mass spectrometry.
Black: Multilayer polyethylene
Pink: slow distillation (1h)
Brown: Annealed copper
Fig. 23: Chromatogram of the oils obtained with different pipes
Conclusion: We did not detect any difference in the oils obtained. However it is not improbable for phthalates to be present in the oils, but in too much weak concentrations to be detected by the technique used. The shower hosepipe used for this experiment had not been used a lot and it is only after a series of heating and cooling cycles that it deteriorates. So, it is possible to use a copper pipe as Moroccans do but the device will lose mobility. Therefore we would need to put the dish+the condenser on the same rotating plate.