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For the first time, graphitized carbon particles with a high surface area have been prepared and evaluated as a new material for probing direct electrochemistry of hemoglobin (Hb). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) imaging revealed that the carbon monolithic skeleton was constructed by a series of mesopores with irregular shapes and an average pore diameter of ~5.6 nm. With a surface area of 239.6 m(2)/g, carbon particles exhibited three major Raman peaks as commonly observed for carbon nanotubes and other carbon materials, i.e., the sp(3) and sp(2) carbon phases coexisted in the sample. A glassy carbon electrode modified with carbon monoliths and didodecyldimethylammonium bromide exhibited direct electron transfer between Hb molecules and the underlying electrode with a transfer rate constant of 6.87 s(-1). The enzyme electrode displayed a pair of quasi-reversible reduction-oxidation peaks at -0.128 and -0.180 V, reflecting the well-known feature of the heme [Fe(3+)/Fe(2+)] redox couple: a surface-controlled electrochemical process with one electron transfer. This reagentless biosensing approach was capable of detecting H(2)O(2), a simple molecule but plays an important role in analytical and biological chemistry, as low as 0.1 μM with linearity of 0.1-60 μM and a response time of <0.8 s, comparing favorably with other carbon based electrodes (5 s).

A CD-modified capillary electrophoretic method has been developed for achiral and chiral analysis of seven bioactive compounds isolated from the fruiting body of Antrodia camphorata. Such important target analytes exhibit similar chemical structures and are known for their diverse properties including antioxidant and anticancer effects. The analytes were separated in 25 min using a pH 9.3, 20 mM sodium borate buffer containing 20 mM methyl-b-CD and 30 mM sulfobutylether-b-CD. With the exception of the optical isomer pairs (antcin B or zhankuic acid A, zhankuic acid C, and antcin A), the remaining bioactive compounds including the chiral pair antcin C were baseline-separated. Analysis time was noticeably longer to baseline separate all of the above chiral pairs ($38 min) by adding 5% DMF to the running buffer. The migration order was reversed compared with the HPLC elution. More hydrophobic compounds complexed favorably with methyl-b-CD and emerged earlier in the electropherogram than their more hydrophilic counterparts which were strongly associated with sulfobutylether-b-CD. The simple capillary electrophoretic method developed was applicable for rapid separation and characterization of several important bioactive compounds isolated from the fruiting body of A. camphorata.

The chromatographic performance of two types of core-shell particles and two fully porous particles packed in 2.1 ID × 50 mm columns was investigated. Comparisons of the performances of the EiS-150-C(18) to that of the Kinetex-1.7 μm-C(18), Acquity-BEH-1.7 μm-C(18), and Zorbax-XDB-1.8 μm-C(18) are made and discussed. The physical factors that govern the performance of these columns, such as particle size distribution and column external, total, and particle porosity of the C(18) packing materials were among the prime foci of investigation. The differences in the mass transfer behavior measured using naphtho[2,3-a]pyrene between these columns provides an indication of improved performance of the new EiS-150-C(18) column. The minimum reduced height equivalent to a theoretical plate (HETP) value for the EiS-150-C(18), h(min) = 1.95, was achieved and was comparable to that obtained from the C(18) phases of the Kinetex (h(min) = 2.53), the Acquity (h(min) = 2.26), and the Zorbax (h(min) = 2.57) columns. This study reveals the importance of the dimension of the shell thickness in controlling the performance of columns packed with shell particles in narrow bore columns.

Centrifugally driven micro-fluidic discs (-CDs) have attracted significant interest within the analytical science community over the last decade, primarily being focused on the potential of such platforms for performing parallel and/or multiplex biological assays and further application in biomedical diagnostics. More recently, -CD based 5 devices have also been applied to environmental analysis as platforms for multisample extraction and transportation, prior to off-disc analysis in the laboratory.Therefore, this review critically summarises recent developments with -CD platforms for sample extraction, preconcentration, fractionation and purification in bioanalytical and environmental applications. In addition to also summarising the 10 common methods employed in the fabrication of -CD platforms, as applications of -CDs in sample extraction are generally based on enclosed series of extraction phases/micro-columns, the preparation of these stationary phases in micro-fluidic channels embedded in -CDs is also discussed. 15 KeywordsCentrifugally driven micro-extraction, micro-fluidic discs (-CD), lab-on-a-disc, sample extraction, preconcentration, fractionation, purification, packed stationary phase, monolithic stationary phase, electrophoretic separations.