Buffering agents sodium hydroxide

Hydrosulfite may be purchased as a proprietary formulation containing buffering and stabilizing agents, usually as a dry powder, but sometimes as a solution. The powder is pyrophoric and should be kept dry to avoid the possibiHty of fires. Alternatively, solutions of sodium hydrosulfite may be generated on-site by using a purchased solution of sodium borohydride and sodium hydroxide to reduce sulfur dioxide. 

Chemical/Physical. Decomposes at elevated temperatures forming methyl isocyanate (Windholz et al., 1983) and nitrogen oxides (Lewis, 1990). Hydrolyzes in water to 1-naphthol and 2-iso-propoxyphenol (Miles et al., 1988). At pH 6.9, half-lives of 78 and 124 d were reported under aerobic and anaerobic conditions, respectively (Kanazawa, 1987). Miles et al. (1988) studied the rate of hydrolysis of propoxur in phosphate-buffered water (0.01 M) at 26 °C with and without a chlorinating agent (10 mg/L hypochlorite solution). The hydrolysis half-lives at pH 7 and 8 with and without chlorine were 3.5 and 10.3 d and 0.05 and 1.2 d, respectively. The reported hydrolysis half-lives of propoxur in water at pH 8, 9, and 10 were 16.0 d, 1.6 d, and 4.2 h, respectively (Aly and ELDib, 1971). In a 0.50 N sodium hydroxide solution at 20 °C, the hydrolysis half-life was reported to be 3.0 d (ELDib and Aly, 1976). 

In addition to the buffers previously mentioned, other agents have also been employed to adjust the pH of nebulization solutions for drug stability and/or solubility reasons (Steckel et al., 2003). These agents include hydrochloric acid, sulfuric acid, and sodium hydroxide, and all have been used in marketed products, as seen in Table 5. 

Didanosine is extremely acid labile at pH values below 3, so one ofthe formulations contains buffering agents (dihydroxyaluminium sodium carbonate and magnesium hydroxide) to keep the pH as high as possible to minimise the acid-induced hydrolysis. Ciprofloxacin forms insoluble non-absorbable chelates with these metallic ions in the buffer so that its bioavailability is markedly reduced. See also Quinolones + Antacids or Calcium compounds , p.328. 

Dissolve 12.52 g of Na2HPOz 2H2O (Sorensen s buffering agent) in 500 ml of distilled water. Set the solution to pH 10 with 0.5 m sodium hydroxide solution and make up to 1 litre with distilled water. If the solution is to be stored for a long period, the pH must be checked and adjusted as... 

Buffer agent for pH control 4.5-6.5 Citric acid sodium hydroxide (50%) 0.30, 0.14... 

The location of PEG chains on the surface of PEG PLA nanospheres was checked by a degradation test (Bazile et al, 1995). The particles were incubated in sodium hydroxide solutions for different incubation times until total destruction, and the solutions were then neutralized by addition of phosphate buffer. The optical densities of these solutions (ODl) were measured after addition of iodine complexation agent. Control experiments... 

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