Separation of peptides by HPLC using a surface-confined ionic liquid stationary phase.

A butylimidazolium bromide surface-confined ionic liquid stationary phase was synthesized in-house. The synthesized phase was investigated for the separation of five peptides (Gly-Tyr, Val-Tyr-Val, leucine enkephalin, methionine enkephalin, and angiotensin-II). The peptides were successfully separated in less than 5 min. The effect of trifluoroacetic acid (TFA) on the separation of peptides was evaluated with results confirming that TFA was not acting as ion-pairing agent in separation of peptides on this phase.

Preparation and analysis of 1-chloronaphthalene for highly refractive electrowetting optics.

High-index oils are critical to the performance of optical electrowetting devices, such as lenses, prisms, and retroreflectors. Herein, the preparation and electrowetting analysis of 1-chloronaphthalene are reported. When 1-chloronaphthalene is mixed with small amounts of an alkane, the following properties can be achieved: refractive index > 1.60, viscosity < 5 cP for rapid switching, operation at <10 V, and +/-45 degrees of electrowetting modulation around the condition for a flat meniscus (90 degrees ).

Characterization of a novel pyridinium bromide surface confined ionic liquid stationary phase for high-performance liquid chromatography under normal phase conditions via linear solvation energy relationships.

Utilizing linear solvation free energy relationship methodology, a novel pyridinium bromide surface confined ionic liquid (SCIL) stationary phase was characterized under normal phase high-performance liquid chromatographic conditions. A limited set of neutral aromatic probe solutes were utilized to rapidly assess the utility of the LSER model, using mobile phases of hexane modified with 2-propanol. The excellent correlation of the global fit across the mobile phase composition range used in this study for the experimental and calculated retention values (R(2)=0.994) indicates that the LSER model is an appropriate model of characterizing this polar bonded phase under normal phase conditions. For a limited subset of compounds, retention on the pyridinium bromide SCIL stationary phase is more highly correlated with that obtained on a cyano column than on a diol column under NP conditions.

Studies on the chemical properties of the acetylcholine receptor site of the frog neuromuscular junction.

The effect of a water-soluble carbodiimide has been used to study the nature of the presumed anionic part of the acetylcholine (ACh) receptor at the frog neuromuscular junction. The ACh sensitivity has been measured by the moving fluid electrode method and by recording end plate potentials with microelectrodes. The carbodiimide blocked ACh sensitivity without marked effect on the membrane resistance or potential difference. The conditions of reversibility of the block and the results obtained with phospholipids suggest that a carboxyl group is important in the combination of ACh with the receptor.