An immobiline DryStrip application method enabling high-capacity two-dimensional gel electrophoresis

In the field of proteomics the need to detect low-abundance cellular components, such as regulatory proteins, is of critical importance. Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) is one of the most commonly used separation tools for these biological investigations. In this paper we report an alternative micropreparative 2-D PAGE sample application method, called the "paper bridge loading" method. This method makes it possible to apply a larger sample volume to commercially available immobilized pH gradient (IPG) strips. The Vh products required for focusing are only marginally longer than those used in analytical experiments. The method was compared to traditional cup loading and in-gel rehydration. With 18 cm long narrow-range Immobiline DryStrip pH 4.5-5.5, the "paper bridge" method allowed the application of 10 mg human plasma proteins compared to 3 mg with traditional loading methods. The corresponding figures using Escherichia coli sample was found to be 6 mg and less than 2 mg, respectively. The paper bridge method also showed the best results in terms of spot resolution and separation of high molecular weight proteins.     

Bond additivity corrections for G3B3 and G3MP2B3 quantum chemistry methods

We have developed bond additivity correction (BAC) procedures for the G3-based quantum chemistry methods, G3B3 and G3MP2B3. We denote these procedures as BAC-G3B3 and BAC-G3MP2B3. We apply the procedures to compounds containing atoms from the first three rows of the periodic table including H, B, C, N, O, F, Al, Si, P, S, and Cl atoms. The BAC procedure applies atomic, molecular, and pairwise bond corrections to theoretical heats of formation of molecules. The BAC-G3B3 and BAC-G3MP2B3 procedures require parameters for each atom type but not for each bond type. These parameters have been obtained by minimizing the error between the BAC-G3B3 and BAC-G3MP2B3 predictions and the experimental heats of formation for a 155 molecule reference set, containing open and closed shell molecules representing various functional groups, multireference configurations, isomers, and degrees of saturation. As compared to former BAC-MP4, BAC-G2, and BAC-hybrid methods, BAC-G3B3 provides better agreement with experiment for a wider range of chemical moieties, including highly oxidized species involving SOx s, NOx s, POx s, and halogens. The BAC-G3B3 and BAC-G3MP2B3 procedures are applied to an extended test suite involving 273 compounds. We assess the overall quality of BAC-G3B3 with experiments and other theoretical approaches. For the reference set, the average error for the BAC-G3B3 results is 0.44 kcal/mol as compared to 0.82 kcal/mol for the raw G3B3. For the extended test set, the average error for the BAC-G3B3 results is 0.91 kcal/mol as compared to 1.38 kcal/mol for the raw G3B3. As compared to the other BAC procedures, the improved predictive capability of BAC-G3B3 and BAC-G3MP2B3 procedures is, to a large extent, due to the improved quality of G3-based methods resulting in much smaller BAC correction terms.     

Application of solid-phase microextraction-gas chromatography-mass spectrometry to characterize intermediates in a joint solar-microbial process for total mineralization of Aroclor 1254

A combined solid-phase microextraction-GC-MS analytical technique was used to monitor the formation of metabolites in the biodegradation of biphenyl, which were originally obtained from the solar photodechlorination of Aroclor 1254 by Pseudomonas pseudoalcaligenes KF707 and Burkholderia sp LB400. In both cases, the following metabolites were detected: 2-hydroxybiphenyl (2-OH-BP), 2,3-dihydroxybiphenyl (2,3-di-OH-BP), and benzoic acid, which was detected as its benzoate derivative 1-methylethylbenzoate. A time course study for the formation and disappearance of these metabolites was used to construct a degradation pathway, which in both cases, involved the formation of 2-OH-BP and 2,3-di-OH-BP.     

Enantioseparations using capillary electromigration techniques in nonaqueous buffers

This review summarizes recent developments in the field of enantioseparations in capillary electromigration techniques using nonaqueous background electrolytes. The more established and rather intensively reviewed field of nonaqueous chiral capillary electrophoresis (NAQ-CE) is covered in less detail whereas more attention is paid to the relatively new field of nonaqueous capillary electrochromatography (NAQ-CEC).     

Pulsed photothermal phase-shift spectroscopy for weak absorption measurement

A novel photothermal phase-shift spectroscopy configuration based on the retro-reflected beam interference has been developed and its operational principle is described. The weak absorption measurement ability of this technique is experimentally proven with a water/ethanol solution of standard Pyronine G dye and the limit of detection is found to be 1.8 x 10(-6) absorbance. Potential applications of the technique are discussed.