Disposable plastic containers

If the substance is unaffected by exposure to the air, it may be weighed on a watch glass, or in a disposable plastic container. The weighing funnel (Fig. 3.8) is very useful, particularly when the solid is to be transferred to a flask having weighed the solid into the scoop-shaped end which is flattened so that it will stand on the balance pan, the narrow end is inserted into the neck of the flask and the solid washed into the flask with a stream of water from a wash bottle. 

In a study recently carried out in Hong Kong on disposable plastic containers for take-away meals the migration of styrene oligomers, heavy metals and the overall migration from plastic containers and, where present, their lids were determined into food simulants under different test conditions. Results showed that all the disposable plastic container samples met the safety standards for heavy metals and residual styrene monomers. Hence, with the proper use of disposable plastic containers, they would be unlikely to cause a food... 

Make up all stocks using sterile disposable plastic containers and pipets. Washed glass items can be contaminated with detergents that are toxic to the eggs. Filter aU concentrated stocks through 0.45-pm Milhpore filters into sterile plastic tubes. Store frozen at 20°C. 

All reagents and materials should be as free of metal ion contamination as is practically possible. The highest anal nical grade of chemicals, and in particular water, should be used. Disposable plastic containers are preferable to glassware which, if unavoidable, should be of borosilicate glass, washed with 1 M hydrochloric acid, and rinsed with dek>nized water until neutral to litmus. 

Note When working with resins, always use disposable plastic containers that will not be dissolved by propylene oxide (for Caution, see Appendix 4). Leftover resin can be polymerized and disposed of according to safety office guidelines. Material that comes into contact with resin is hazardous waste, as resins are carcinogenic. 

For dealing with smaller volumes of solution, micropipettes, often referred to as syringe pipettes, are employed. These can be of a push-button type, in which the syringe is operated by pressing a button on the top of the pipette the plunger travels between two fixed stops and so a remarkably constant volume of liquid is delivered. Such pipettes are fitted with disposable plastic tips (usually of polythene or polypropylene) which are not wetted by aqueous solutions, thus helping to ensure constancy of the volume of liquid delivered. The liquid is contained entirely within the plastic tip and so, by replacing the tip, the same pipette can be employed for different solutions. Such pipettes are available to deliver volumes of 1 to 1000 pL, and the delivery is reproducible to within about 1 per cent. 

Recycling polymers is one way to minimize the disposal problem, but not much recycling occurs at present. Only about 25% of the plastic made in the United States is recycled each year, compared with 55% of the aluminum and 40% of the paper. A major obstacle to recycling plastics is the great variation in the composition of polymeric material. Polyethylene and polystyrene have different properties, and a mixture of the two is inferior to either. Recyclers must either separate different types of plastics or process the recycled material for less specialized uses. Manufacturers label plastic containers with numbers that indicate their polymer type and make it easier to recycle these materials. Table 13-5 shows the recycling number scheme. 

Approximately 11.8 million pounds of hexabromobiphenyl were used in commercial and consumer products in the United States, most in the production of plastic products with an estimated use life of 5 10 years (Neufeld et al. 1977). Since the cessation of production, all of these products, such as TV cabinet and business machine housings, must have been disposed ofby land filling or incineration (Neufeld et al. 1977). The formation of polybrominated dioxins (PBDDs) and polybrominated dibenzofurans (PBDFs) during the incineration of plastics containing PBBs remains a distinct possibility (Luijk and Covers 1992 O Keefe 1978). 

Figure 2-12 (a) Microliter pipet with disposable plastic tip (b) Enlarged view of disposable tip containing polyethylene filter to prevent aerosol from contaminating the shaft of the pipet. (c) Volume selection dial set to 150 jiL. [Courtesy Roinin Instrument Co Emeryville, CA.J... 

A microwave oven equipped with Pello 3420 Load Cooler attachment is set at 25°C and full power. Two beakers, each filled with 500 ml of water, are placed in previously determined hot spots in the microwave oven (see pages 102-103). Grids containing the thin cryosections are floated (section side down) sequentially on small drops of 0.15% glycine and 1% BSA for 15 sec and 5 min, respectively. The reagent drops are placed on a clean disposable plastic surface which has been placed on the cold spot in the oven (an area between the two beakers of water). The local temperature is controlled using the microwave temperature probe immersed in a tube of water placed close to the grids. 

Shut off all possible sources of ignition. Instruct others to keep a safe distance. Wear breathing apparatus, eye protection, laboratory coat, and nitrile rubber gloves. Cover the spill with a 1 1 1 mixture by weight of sodium carbonate or calcium carbonate, clay cat litter (bentonite), and sand. When the acrylonitrile has been absorbed, scoop the mixture into a plastic container and package for disposal by burning. Ventilate area well to evaporate remaining acrylonitrile and dispel vapor.3,8"10... 

In an attempt to eliminate some of these problems, a new centrifuge (Centritech ) was specially designed for mammalian cell separation (Johnson et al., 1996). This centrifuge operates with Rf > 0 and generates a centrifugal field intensity up to 320 g. It operates in a closed system and contains a presterilized and disposable plastic insert, which eliminates the... 

Cells may be grown in dishes or flasks where the initial inoculum varies from 0.2 X 106 up to 2 X 106. The containers may be glass or plastic. The plastic ware is obtained in sterile wraps from commercial suppliers and is specially prepared for use in cell culture (Fig. 3.2a) (see Appendix 3). The glass bottles are usually medical flat bottles but any bottle with a flat side will do provided it is washed correctly and sterilised before use (see Chapter 8). To a large extent the disposable plastic flask has now replaced the glass bottle. 

The selective treatments of flame-retardant plastics are fulfilled when the WEEE plastics are treated (recovered, recycled, thermally disposed) together with other wastes, as is the case with energy recovery processes that are currently practiced in Europe.78 79 In this scenario, the joint recovery of plastics containing brominated flame-retardants with other materials complies with the purpose of the WEEE Directive without the removal requirement of Annex II. Recent technical studies and legal reviews demonstrate that WEEE plastics containing brominated flame-retardants are compatible with the EU WEEE Directive without separation and removal prior to the waste treatment. This has been confirmed by the 2006 EU Member States guidance on the separation requirements of the WEEE Directive.80... 

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