Glass-ware

Use only distilled water when preparing aqueous solutions, washing precipitates with water, rinsing glass ware, and so on. 

Before washing glass ware containing residues of white or red phosphorus, immerse it into baths with a solution of copper sulphate (take them from the laboratory assistant). 

Detergents are ideal for washing laboratory glass ware. 

The reduction and oxidation of radicals are discussed in Chapter. 6.3-6.5. That in the case of radicals derived from charged polymers the special effect of repulsion can play a dramatic role was mentioned above, when the reduction of poly(U)-derived base radicals by thiols was discussed. Beyond the common oxidation and reduction of radicals by transition metal ions, an unexpected effect of very low concentrations of iron ions was observed in the case of poly(acrylic acid) (Ulanski et al. 1996c). Radical-induced chain scission yields were poorly reproducible, but when the glass ware had been washed with EDTA to eliminate traces of transition metal ions, notably iron, from its surface, results became reproducible. In fact, the addition of 1 x 10 6 mol dm3 Fe2+ reduces in a pulse radiolysis experiment the amplitude of conductivity increase (a measure of the yield of chain scission Chap. 13.3) more than tenfold and also causes a significant increase in the rate of the chain-breaking process. In further experiments, this dramatic effect of low iron concentrations was confirmed by measuring the chain scission yields by a different method. At present, the underlying reactions are not yet understood. These data are, however, of some potential relevance to DNA free-radical chemistry, since the presence of adventitious transition metal ions is difficult to avoid. 

Earthen and glass-ware vessels piece by piece,... 

Phase separation may have undesirable consequences if it occurs during annealing of Pyrex glass ware the gpod solubility of one of the separated phases (that containing more Na20 and B2O3)) considerably impairs the chemical durability. Therefore... 

In industrial practice, glass ware is annealed in special annealing lehrs. Intermittent lehrs arc used only exceptionally continuous melting and machine forming lines only... 

Toughening of glass is most frequently used with sheet glass intended for vehicle wind screens, building items (e.g. all-glass doors) etc. Toughening is also employed in the manufacture of domestic glass-ware, spectacle lenses, instrument parts, etc. 

All reagents used for the PERT assay must be free of any contaminating MS 2-DNA. To avoid carryover contamination, set up at least two different rooms for work with materials before and after PCR. Use different sets of equipment, chemicals, and disposables. If possible, avoid the use of pH probes and spatula. If glass ware is used, do not have them washed in a central facility (where it can get contaminated), wash and bake it personally (at 240°C for 5 h). It may be a good idea to have a friend at a different location (where no work with MS2 is carried out) who can prepare solutions. Use only positive displacement pipetes or pipet tips with filters especially for PCR. The published recommendations in ref. 17 are useful. 

The micronutrient cations can be estimated in a single extraction with diethylene triamine pentaacetic acid (DTPA) which has excellent chelating property with the micronutrient elements. Adequate precaution must be taken against any likely contamination from the reagents and glass wares in micronutrient assay work. Only double distilled water should be used. Specific hallow cathode lamps for each elements are used on AAS and requisite standards for instrument calibration are prepared as per instructions in the operation manual. 

General note The entry of moisture during the oprations must be scrupulously avoided and glass ware must be perfectly dry. The salt filtered off may contain small particles of potassium. The safest way to destroy this is to spread the salt on a large surface as soon as the adhering solvent has evaporated, the salt is collected and thrown in a beaker filled with water. 

The acid chemicals like nitric, phosphoric and sulfuric acid used in this study were of analytical grades and supplied by Panreac Company. C02 gas of 99.999% purity and natural gas containing 100 ppm H2S were provided by Saudi Gas Company. All glass wares were of Pyrex, washed with demineralized water and dried in an oven at 105°C. 

ALWAYS work with clean equipment. You must take the time to scrupulously clean your equipment before you start any experiment. Contaminated glass-ware will ultimately cost you additional time, and you wiU experience the frustration of inconsistent results and lower yields. Dirty equipment is the primary cause of reaction failure at the microscale level. 

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