Tridodecylmethylammonium chloride

The heparin-sensitive electrode at the beginning of this chapter is similar to the Ca2+ electrode, but the ion exchanger in the membrane is tridodecylmethylammonium chloride, (C,2H25)3NCH C1- Cl in the membrane exchanges with the negatively charged heparin. 

A tetraruthenated porphyrin was electropolymerised onto glassy carbon and used to catalyse the oxidation of nitrite to nitrate, with the resultant current giving a selective measure of the concentration of nitrite ion [81]. As an alternative method, soluble poly(3-octyl thiophene) [82] was cast along with tridodecylmethylammonium chloride onto glassy carbon, to give electrodes with superior selectivity over PVC-based membranes to lipophilic ions such as bromide or nitrate. 

For comparison purposes, selectivity data is also presented for membranes prepared with a typical quaternary ammonium exchanger, tridodecylmethylammonium chloride (TDMA-Cl) (1). All the porphyrin species tested yield selectivities which clearly deviate from that observed with TDMA-Cl. More importantly, two compounds, Mn[TPPP]Cl (i) and Sn[TPP]Cl2 (5.), show extraordinary selectivity toward thiocyanate and salicylate, respectively. In the case of Mn[TPPP]Cl, adding conjugated and bul)cy substituents in the form of twelve phenyl groups to the basic tetraphenylporphyrin [TPP] structure dramatically enhances the response and selectivity toward thiocyanate... 

Selectivity, stability and lifetime are sensitive to the type and amount of quaternary salt and mediator (Table 3.18). The best model based on TDDM (tridodecylmethylammonium chloride) with 5-PP(5-phenylpentanol) was suitable for use in blood serum. Again, increasing the alkyl chain length results in improved Nernstian slopes and simultaneously enhances lipophilicity and, in turn, the lifetime of the sensor (68). 

However, the majority of the antimicrobial-treated CVCs available on the market (Table 12.4) are obtained by adsorption of the drug onto the catheter surface, since this method is facile, inexpensive, and potentially apphcable for a wide range of drugs. Only in the two types of CVCs treated with silver, the antimicrobial agents are impregnated in the polymer bulk. Often, to improve drug affinity for the device surface, cationic surfactants are used, such as tridodecylmethylammonium chloride (TDMAC) and benzalkonium chloride employed for the adsorption of minocycline/rifampin and heparin, respectively. 

The selectivity of membrane-based ISEs is somewhat controlled by the relative lipophilicity of the ions. In particular, the response of ISEs based on anion-exchangers, such as tridodecylmethylammonium chloride (TDMAC), that simply form ion pairs with anions follows the Hofineister series or classical response lipophilic organic anions > CIO > SCN > T > N03" > Br > NOj > Cf > HC03 > HPO/, SO/ . Analogously, ISEs based on lipophilic borates, such as potassium tetrakis(p-chlorophenyl)borate (KTpClPB), which forms ion pairs with cations, respond to cations in the following order Ag > Hg > Cs > Rb, NH/ > > Lf... 

Lee proposed reference electrodes [51] with polymer membranes directly deposited onto the surface of a metal. The polymer membrane incorporate both anion-and cation-exchange sites (i.e. potassium tetrakis(p-chlorophenyl)borate and tridodecylmethylammonium chloride). Best results were obtained with polyurethane combined with poly (tetramethylene ether glycol) (PTMEG). 

Neutral carrier-based membranes require the addition of a lipophilic ion-exchanger for proper functioning. This ion-exchanger forms the counterion of the complexed analyte ion in the membrane. Its concentration should not be too large in order to allow for a substantial concentration of unbound ionophore in the membrane. Eor instance, a cation-selective membrane may contain the ionophore and the lipophilic tetraphe-nylborate derivative cation-exchanger potassium tetrakis(4-chlorophenyl)borate, while anion-selective membranes may be doped with tridodecylmethylammonium chloride as anion-exchanger in addition to the ionophore. 

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