Extractables glass containers

The USP stipulates a test and limits for alkali extraction from container soda-lime glass (5). Specially prepared double-distilled water is used to extract the glass for one hour at 121 °C in a steam autoclave on a strict cycle program. An aliquot of the extract is then back titrated with... 

A solvent-free strategy for the synthesis of thiazoles involved mixing of thioamides with a-tosyloxy ketones in a clay-catalyzed reaction (Scheme 7). The typical procedure entailed mixing of thioamides and in situ produced a-tosyloxy ketones with montmorillonite K-10 clay in an open glass container. The reaction mixture was irradiated in a microwave oven for 2-5 min with intermittent irradiation and the product was extracted into ethyl acetate to afford 2-substituted thiazoles in 88-96% yields [8]. 

Storing aqueous samples in glass containers prior to being examined for polynuclear aromatic hydrocarbons at the ng 1 1 level can also be a problem. There is evidence of adsorption of the hydrocarbons onto the glass surface. This problem is considerably reduced by putting the extracting solvent in the bottle before introducing the water sample. 

Wastewater samples have usually been collected in precleaned amber glass containers. Both discrete and composite samples have been used for the analysis of effluents and influents of WWTPs. Unpreserved samples are normally stored at 4 °C for 48 h, or frozen [48]. Other authors add chemical agents such as methanol, sulfuric acid, or mercuric chloride to prevent bacterial activity during storage, and/or store the samples in supports used for extraction [26,35,57]. 

Ideally samples from living organisms should be extracted without any delay to prevent autoxidative or enzymic deterioration of their lipid constituents. If this is not feasable the sample should be frozen immediately and stored at — 20 °C in a glass container under nitrogen. Often lipids will be extracted into an organic solvent and during this and subsequent steps in the analytical procedure minimal exposure of the lipids to air, light and heat is very important to prevent oxidation or destruction of the lipids. 

FIGURE 8 Aluminum extracted from type II glass containers and from polyethylene containers by action of NaCl, KC1, albumin, glucose, heparin, HC1, and NaOH solutions after 30 and 60 days storage at room temperature. The three different albumins are A, bovine (Merck) B, bovine (Reagen), and C, egg (Sigma) [50]. 

The electrical conductivity (or resistivity) of an aqueous pigment extract is determined from the electrical conductance (or resistance). For standards, see Table 1 ( Resistivity ). Apparatus centrifuge with glass containers, resistance measurement bridge, electrolytic cell. 

To an equimolar (1 mmol) mixture of 2-methylquinoline la (143 mg) and benzoyl chloride 2a (140 mg) placed in an open glass container, silica gel (silica gel 60, 230-240 mesh, Merck) (300 mg) was added and the reaction mixture was irradiated in a microwave oven at 400 W power for 4 min. Upon completion of the reaction, as followed by TLC examination, the product is extracted into dichloro-metliane (3xl0mL). The solvent was evaporated and the resulting crude material was purified on a silica gel plate (eluent CCl4-Et20) affording the l-phenyl-2-(quinol-2-yl)-etliane-l-one 3a in 91% yield. 

Certain widely used solvents such as diethyl ether or methylene chloride are highly volatile. Excess pressure buildup may cause rapture of the separatory funnel. Many accidents have been reported. It is important to vent out the excess pressure, especially after the first time shaking the sample with the solvent. Before extraction, rinse the separatory funnel with a few milliliters of the solvent. A glass container that has even a slight crack should not be used for extraction. 

All samples stored at 4°C in glass containers protected from light and air oxidation extracted within 7 days of collection and analyzed within 7 days of extraction residual chlorine if present in aqueous samples must be removed by adding Na C ( 100 mg/L sample). 

Samples collected in glass containers, refrigerated, and extracted within 7 days of collection and analyzed within 40 days of extraction. 

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