The development of an all-glass separation-based sensor using microdialysis coupled to microchip electrophoresis with amperometric detection is described. The system includes a flow-gated interface to inject discrete sample plugs from the microdialysis perfusate into the microchip electrophoresis system. Electrochemical detection was accomplished with a platinum electrode in an in-channel configuration using a wireless electrically isolated potentiostat. To facilitate bonding around the in-channel electrode, a fabrication process was employed that produced a working and a reference electrode flush with the glass surface. Both normal and reversed polarity separations were performed with this sensor. The system was evaluated in vitro for the continuous monitoring of the production of hydrogen peroxide from the reaction of glucose oxidase with glucose. Microdialysis experiments were performed using a BASi loop probe with an overall lag time of approximately five minutes and a rise time of less than 60 seconds.

An all-PDMS on-line microdialysis-microchip electrophoresis with on-chip derivatization and electrophoretic separation for near real-time monitoring of primary amine-containing analytes is described. Each part of the chip was optimized separately, and the effect of each of the components on temporal resolution, lag time, and separation efficiency of the device was determined. Aspartate and glutamate were employed as test analytes. Derivatization was accomplished with naphthalene-2,3,-dicarboxyaldehyde/cyanide (NDA/CN−), and the separation was performed using a 15-cm serpentine channel. The analytes were detected using LIF detection.

The Hansen solubility parameters (HSPs) of asphaltene model compounds were determined experimentally via solubility testing. For the test, we synthesized various archipelago- and continental-type molecule model compounds: 5 were steroid-derived naphthoquinoline compounds; 14 were phenanthrene/pyrene-derived compounds; 2 were nickel porphyrins; and 1 was an alkyl hexabenzocoronene molecule. Some of them contain nitrogen as the quinoline or porphyrin structure, oxygen as the furan structure, and sulfur as the thiophene structure. Using the Hansen sphere method, the HSPs δd, δp, and δh were successfully determined with only small errors, with values of 18.7–21.0, 2.7–8.1, and 2.2–6.5 MPa1/2, respectively. For real asphaltenes, these values were about 19, 4, and 4 MPa1/2, respectively. The solubility characteristics of the model compounds were found to be complex, because there is not clear relationships between solubility and chemical structures. Even slight structural differences, such as the type and location of heteroatoms, greatly changed the Hansen sphere radius, R 0. The HSP analyses will enable the development of a mixing strategy for model compounds, to mimic asphaltene.

γ-Lactam derivatives with multiple contiguous stereogenic carbon centers are ubiquitous in physiologically active compounds. The development of straightforward and reliable synthetic routes to such chiral structural motifs in a stereocontrolled manner should thus be of importance. Herein, we report a strategy to construct polycyclic γ-lactam derivatives that contain more than two contiguous stereogenic centers in an enantioselective as well as atom-economic manner. Moreover, we have achieved the first enantioselective synthesis of strigolactam derivative GR-24, a racemic variant of which is a potential seed germination stimulator and plantgrowth regulator. A key of the procedure presented here is a nickel(0)/chiral phosphoramidite-catalyzed asymmetric [2+2+1] carbonylative cycloaddition between readily accessible ene-imines and carbon monoxide, which proceeded enantioselectively to furnish up to 90% ee (>99% ee after recrystallization). The results of mechanistic studies, including the isolation of a chiral heteronickelacycle, support that the enantioselectivity on the two contiguous carbon atoms of the γ-lactams is determined during the oxidative cyclization on nickel(0).

This review describes the design and synthesis of compounds that are functionalized to mimic the physical and chemical behavior of asphaltenes. The constructive interplay between synthetic compounds and modern analytical techniques is highlighted.