On the question of biological control methods for plastic materials

Biological and chemical testing of plastic materials and devices needs the extraction of the analyzed sample. Polyamide was used as the model material and various effects of the extraction conditions on some biological (intracutaneous irritation, rat heart in situ, blood pressure on rats) and chemical (mass of the residue after evaporation) tests were studied. The material was extracted at 120, 55 and 37 degrees C for 0.5, 72 and 504 hr, respectively. Moreover, the polyamide was extracted at 120 degrees C for 5, 10, 15, 20, 25, 30, 60 and 120 min. Extracts were evaporated on the water bath. The increasing extraction period at 120 degrees C resulted in the increase in values of intracutaneous irritation as well as the residue mass after evaporation and in the decrease of rat heart amplitude and frequency. It was found that the extraction conditions at different temperature mentioned above were not equivalent. Various methods of extract concentration were also tested. Extracts evaporated at 35 degrees C in vacuo decreased the blood pressure more than those evaporated in the water bath.