Separation of asparagine, valine and tetraethylammonium ions overlapping in an ion mobility spectrum by clustering with methanol introduced as a modifier into the buffer gas

We introduced methanol into the buffer gas of an ion mobility spectrometer-mass spectrometer and mobilities changed depending on ion structures; baseline separation of valine, asparagine, and tetraalkylammonium ions was achieved.

The voltammetric study of the reduction of tetraalkylammonium perchlorate by Fe(TPP)2−

Tetraalkylammonium ions react with Fe ( TPP )2− to form Fe ( TPP )( R )− and trialkylamine. The tetrabutylammonium cation was verified to be the source of the alkyl group in the product, Fe ( TPP )( R )−, by using (1 H 5 C 2)3(2 H 5 C 2) N − as the cation and 2 H NMR. The reaction of Fe ( TPP )2− with Bu 4 N − was monitored by cyclic voltammetry and thin layer spectroelectrochemistry. The activation parameters were measured, and were most consistent with an electron transfer (ET) mechanism. The rate of the reaction of tetramethyl and tetraethylammonium ions with Fe ( TPP )2− was also examined. The rate constant decreased significantly as the carbon chain length decreased, which was also consistent with an ET mechanism.

Ionic conductances of monkey solitary cone inner segments

1. The membrane properties of cone inner segments dissociated enzymatically from monkey retina were studied under voltage-clamp conditions using patch pipettes in the whole-cell clamp configuration. 2. A noninactivating, voltage-gated calcium current was evoked at potentials positive to -60 mV and peaked between -30 and -20 mV when barium was substituted for calcium. Cadmium (50 microM) but not nickel (50 microM) blocked the current. 3. A large calcium-activated anion current (IAn) was observed when the membrane potential was set to a level between -60 and 30 mV. The reversal potential of IAn was 0 mV with chloride as the sole anion and about -30 and -40 mV when methanesulfonate and D-aspartate, respectively, replaced intracellular chloride to set the equilibrium potential for chloride at -50 mV. IAn inactivated and oscillated when the membrane potential was maintained at depolarized levels, contrary to calcium-activated anionic currents seen in photoreceptors of other species. 4. A sustained-type potassium current was activated by depolarizations positive to -50 mV. The time course of activation and deactivation were voltage dependent. This potassium current was partially blocked by 20 mM tetraethylammonium ions. 5. A transient potassium current was activated by depolarizations positive to -20 mV. This current was blocked by 4-aminopyridine (2 mM) and inactivated with a time constant of approximately 500 ms. The amplitude in response to voltage steps to 45 mV was decreased by prepulses to voltages more positive than -30 mV. 6. Hyperpolarization negative to -65 mV activated an inward current that was completely blocked by external cesium (10 mM). The reversal potential suggested a conductance mechanism permeable to both sodium and potassium ions. 7. A calcium-activated potassium current, which was found in salamander photoreceptors, was not detected. 8. The presence of these conductances is expected to influence the membrane potential and the time course of the light response in monkey cones.