Glassware specialized

Since particle counting has been very sensitive to environmental contamination of air-borne particles and particles adsorbed on glassware, special precautions were taken. Before use, a thorough cleaning of the glassware with chromic acid was achieved. Furthermore, recipients were always rinsed twice before sampling with the water to be examined. When. samples were taken on site, erlenmeyer flasks were used for water sample collection. They were filled up to the neck and immediately sealed with glass stoppers, previously rinsed with the water to be sampled. 

Practical experience enables us to emphasize the simplicity and the efficiency of the activation of aldehydes by their conversion into N- -haloalkyl)heteroarylium halides upon treatment with an azine and a thionyl halide. Preparation of these salts requires a minimum of precautions, and a wide variety of solvents can be used. Special glassware and/or the use of an inert gas is not necessary. Tire salts can be reacted under numerous experimental conditions and, in most cases, it is unnecessary to isolate them. Tire flexibility of the method represents an interesting feature for the study of the reactivity of A-(l-haloalkyl)heteroarylium halides and deserves further investigations in this held. Many elegant compromises can be found in a judicious choice of the precursors and of the experimental conditions, and it is possible to design readily a salt suitable for each individual purpose. 

Many commercially available detergents are suitable for this purpose, and some manufacturers market special formulations for cleaning laboratory glassware some of these, e.g. Decon 90 made by Decon Laboratories of Portslade, are claimed to be specially effective in removing contamination due to radioactive materials. 

Normal laboratory glassware must first be washed and cleaned. It has to be rinsed with deionised water. The clean glassware is sterilised in an oven set at 200 °C for 1 1 hours. It is suitable to cover glassware with aluminum foil to maintain aseptic conditions after removing the glassware from the oven. If aluminum foil is not available, special heat-resistant wrap paper can be used. The sterile glassware must be protected from the air, which has micro-flora, or any contaminants. Avoid the use of any plastic caps and papers. Detach any labelling tape or other flammable materials, as they are fire hazards. 

A discussion of this polymerization method would not be complete without mention of the development of specialized glassware utilized over the years. It has evolved from very elaborate, sophisticated, and specially designed glassware to fairly simple setups. Initially, elaborate break-seal technology was used to complete the entire polymerization process,143 similar to anionic polymerization methodology.17 Break-seal techniques were employed to fully understand many monomer structure-reactivity relationships these techniques are no longer needed. 

One major benefit of performing microwave-assisted reactions at atmospheric pressure is the possibility of using standard laboratory glassware (round-bottomed flasks, reflux condensers) in the microwave cavity to carry out syntheses on a larger scale. In contrast, pressurized reactions require special vessels and scale-up to more... 

In this paper we review the techniques and applications of microwave irradiation in cycloaddition reactions. This mode ofheating requires not only appropriate micro-wave equipment and glassware, but also a new experimental outlook. A special section will focus on modifications of chemo-, regio- and stereoselectivity which result from use of microwaves, and possible explanations of this behavior will be given. 

Rather than perform this analysis in laboratory glassware in a fume cupboard, special pieces of apparatus that hold the flasks and allow several Kjeldahl titrations to be carried out in parallel are employed. 

The digestions can be carried out in up to 40-place multiple heating units using specialized glassware which is commercially available some suppliers are listed below ... 

The EC official method is described in the Official Journal of the European Communities (EC, 1992), and uses specialized glassware. We will base the method on that of MAEE/ADAS (1986, pp. 90-92), (with Crown Copyright permission), but replace the alcohol and diethyl ether (used for washing the residue) with acetone, which is safer and also used in the EC method. The AOAC method is described by Padmore (1990, pp. 80-82). The traditional method uses 0.313 M NaOH, free from carbonate, but the EC method uses 0.23 M KOH. The method is suitable for plant material or animal feeds, but the following pre-treatments may be necessary, especially for feedstuffs. 

Scrupulous cleanliness is an absolute must in working with monolayers [104] all materials used should be of the highest purity solvents and solutions should be dust-free glassware should be cleaned with a special cleaning solution and kept separate from other equipment the film balance should be kept in a clean area on a vibration-free table and surgical gloves should be worn at all times. These necessary precautions have been elaborated in frightening detail in a recent publication [114] and a review [107]. 

Experiments are performed in special laboratory ware made from thin or thick laboratory glass. Thin glassware must be chemically and thermally stable. Ware in which reactions are performed with heating is made from heat-resistant Pyrex glass and quartz. 

Glassware. All special borosilicate glassware was fabricated in-house. Kudema-Danish (K-D) evaporators and the modified Snyder columns were constructed as per the design described previously (25) adsorption glass... 

---