27 KNOWLEDGE Cleaning and maintenance of plastics All polyolefins, such as PE-LD, PE-HD, PP and PMP, as well as the fluoroplastics PTFE, PFA, FEP and ETFE have water-repellent surfaces that are very durable and easy to clean. For cleaning, depending on the level of contamination, commercially available neutral or alkaline detergents can be used. Polycarbonate (PC) labware should not be cleaned with alkaline cleaning agents (> pH 7). Please note that no scrubbing agents or scouring pads should be used for labware made from plastics. Cleaning with dishwashers Labware made from the above-named plastics (except for PE-LD, due to the temperature limit) can be cleaned and dried in a laboratory dishwasher together with other apparatus. Machine cleaning with laboratory dishwashers is gentler to labware than cleaning in an immersion bath. The labware is exposed to the cleaning solution for relatively short rinsing periods when sprayed by the jet or injector nozzles. Due to their light weight, we recommend securing the apparatus to be washed with washing nets to prevent them from tumbling in the water jet. Labware is better protected against scratching when the wire baskets in the washing machine are plastic coated. Cleaning in an ultrasonic bath Plastic labware may be cleaned in an ultrasonic bath. However, direct contact with the acoustic membrane should be avoided. Cleaning in trace analysis To avoid contamination with cations and anions in trace analysis, plastic labware should be allowed to stand with a 1N HCl or HNO3 solution for a maximum of 6 hours at room temperature, and be rinsed afterwards with purified distilled water. For trace analysis conducted in the concentration range of ng/g (ppb) or pg/g (ppt), containers made of the fluoroplastic PFA are particularly suitable, because they have a smooth surface, are easy to clean without carry-over (memory effects) and interaction with the container material.
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