Cation, lipid soluble quaternary ammonium

This technique involves the extraction of the anion of an organic acid as its ion pair with a lipid soluble quaternary ammonium cation (in our case, this... 

Glasses exist that fnnction as selective electrodes for many different monovalent and some divalent cations. Alternatively, a hydrophobic membrane can be made semiper-meable if a hydrophobic molecnle called an ionophore that selectively binds an ion is dissolved in it. The selectivity of the membrane is determined by the structnre of the ionophore. Some ionophores are natnral products, such as gramicidin, which is highly specific for K+, whereas others such as crown ethers and cryptands are synthetic. Ions such as, 1, Br, and N03 can be detected using quaternary ammonium cationic surfactants as a lipid-soluble counterion. ISEs are generally sensitive in the 10 to 10 M range, but are not perfectly selective. The most typical membrane material used in ISEs is polyvinyl chloride plasticized with dialkylsebacate or other hydrophobic chemicals. 

Cerilpyridiniutii chloride is the 1-hexadecylpyridinium chloride (USP/NF-. Eur.Ph.-, BP-, and Martindate-compliant). Lin et al. (33) compared the primaiy ocular and dermal irritations of several quaternary ammonium compounds. They concluded that the irritancy of these compounds is likely to be related to their solubility in addition to their cationic characteristics. Only celylpyridinium chloride is very soluble in both lipids and w er. It appears that not all of the quaternary ammonium compounds studied are irritant, but celylpyridinium chloride was severely irritating to the skin of the test animal. In a recent work. Green et al. (34) confirmed that ophthalmic medications containing celylpyridinium chloride are potentially hazardous to the comeal endothelium. 

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