Ammonia lipid solubility

Cohen and Grisolia then concentrated on the first step in the reaction, obtaining citrulline from ornithine. The reaction appeared to depend on oxygen, a requirement traced to the need for high concentrations of ATP. Physiologically the formation of urea occurs at very low levels of ammonia, which is extremely toxic as it is also lipid soluble and enters cells very easily. Cells are not very effectively buffered against OH. ... 

A gas chromatographic procedure is cited in the BP for the assay econazole nitrate in a cream base". Econazole nitrate is extracted into methanol - 0.6m sulphuric acid, whilst other lipid soluble excipients are extracted into carbon tetrachloride. The aqueous extracts are made alkaline with 2 M ammonia and extracted into Chloroform. An internal standard, 1,2,3,4-tetraphenylcyclopenta-l,3-diene is added to the chloroform extracts and then evaporated to a low volume. Extracts were chromatographed on a 1.5 m x 2.0 mm OV-17 (or equivalent column) at 270°C using nitrogen as carrier gas and flame ionization detection. 

Ammonia and simple aliphatic amines were among the first uncouplers reported for photophosphorylation by Krogmann, Jagendorf and Avron and by Good respectively. Ammonia and simple aliphatic amines in their lipid-soluble, unprotonated forms can freely permeate the thylakoid membrane. Once inside, they can take up protons and be converted to the corresponding ammonium ions [Fig. 10 (B)]. To maintain electrical neutrality, the accumulation of ammonium ions results in the influx of anions. The accumulation of ammonium salts inside consequently results in an osmotic influx of water and swelling of the thylakoids. 

The role of ammonia is in buffering acid and it makes a contribution which is particularly important when the acid load is high. Ammonia produced in the tubular cell cytoplasm diffuses readily across the tubular cell membrane into the tubular fluid. Cell membranes consist largely of lipid material and so are in general permeable to non-polar particles such as ammonia The solubility of ionized particles such as ammonium ions in lipid is very low so that ions permeate cell membranes very slowly. 

The ammonia in the solvent system will convert the mescaline present into its free base form, thus resulting in a more efficient extraction. Ether and methanol are immiscible, with the lipids being more soluble in the former. They are thus removed from the sample, so maintaining the drug component in the methanol (in which it is more soluble) as its free base form. 

The primary and most immediate effect of ammonia exposure is bums to the skin, eyes, and respiratory tract. The topical damage caused by ammonia is probably due mainly to its alkaline properties. Its high water solubility allows it to dissolve in moisture on the mucous membranes, skin, and eyes, forming ammonium hydroxide, which causes liquefaction necrosis of the tissues (Jarudi and Golden 1973). Specifically, ammonium hydroxide causes saponification of cell membrane lipids, resulting in cell disruption and death. Additionally, it breaks down cell stmctural proteins, extracts water from the cells, and initiates an inflammatory response, which further damages the surrounding tissues (Amshel et al. 

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