Automated fractionation studies

Coal liquids, petroleum crudes, and their distillation cuts have been separated into four or five fractions by SEC (5 15). The SEC fractions were analyzed by use of GC. The procedure was performed manually. It was inefficient, and susceptible to human error. The automated fraction collection followed by injection of the fraction into the GC reduces analysis time, and offers an option for collection of the desired number of fractions at predetermined time intervals. The manual collection of up to 10 one-ml fractions is also used in order to study the effectiveness of the automated method. 

The methods employed for the miscible displacement studies were similar to those used in previous experiments (Hu and Brusseau, 1998). We connected a high-performance liquid chromatography (HPLC) pump (Model 301 from Alltech Associates Inc., Deerfield, IL) to the column, and placed a three-way valve in-line to facilitate switching between treatment solutions. Several iodine species (iodide, iodate, and 4-iodoaniline) were used to study transport behavior. We also examined the transport of tritium and bromide, commonly used conservative tracers, so that we could compare their transport behavior with iodine species. For transport experiments of 4-iodoaniline, which is used as a representative refractory organic iodine species, the solution was allowed contact only with glass or stainless steel, to avoid potential interaction of organoiodine with plastics in the column system. Column effluents were collected with an automated fraction collector (Retriever 500, ISCO Inc., Lincoln, NE) for chemical analysis, as described below. 

St. Louis Sample Collection. Ambient aerosols were collected in St. Louis in 6-h Intervals with a TWOMASS automated sequential tape sampler. This sampler fractionated the aerosol into two size classes, fine particles having aerodynamic diameters less than 3pm, and coarse particles with diameters greater than 3pm. It was equipped with a beta-attenuation mass monitor to determine fine-particle mass (11). Only the fine particle filter was examined in this study. Pallflex E70 glass-fiber filter tape with a detachable cellulose backing (Pallflex Inc. Putnam, CT) was used with this sampler. An aerosol sampler operating from the same inlet manifold as the... 

The MudPlT approach was modified in order to perform LCxLC in two separated colunms (SCX and RPLC), which are connected via switching valves and a short RP trapping colunm [50], This allows intermediate emichment and desalting of the fractions eluted from the SCX prior to RPLC-MS analysis. The application of such a system in combination with a (J-TOF instrument has been applied to identification of the Caenorhabditis elegans proteome [51]. In total, 1616 proteins were identified, including 110 secreted/targeted proteins and 242 transmembiane proteins. Many of the 5400 peptides identified in the course of this study contained a PTM such as acetylation and phosphorylation. This type of system has become commercially available as a fully-automated workstation [52-53] (Figure 17.1). 

Some of the advantages of cell monolayer models include the ability to use human instead of animal cell types as well as the ability to perform cellular uptake and bidirectional cell transport studies for evaluation of absorptive and secretory processes. The potential for automation to achieve higher throughput in the early drug discovery setting is an added attraction. Regardless of the cell type used, the utility of these models in transport studies is based on the correlation between permeability properties determined in these models and those obtained in vivo, such as fraction of dose absorbed (Fig. 3). To date, numerous laboratories have established a correlation between apparent permeability coefficients (P pf) from Caco-2 or MDCK cells and in vivo fraction absorbed of drugs in solution [58—62]. Construction of correlation plots for known compounds or reference markers then provides an opportunity for interpolation of fraction absorbed for NMEs for which in vivo fraction absorbed is unknown. 

With the advent of automated analytical SFE equipment, it has become possible to rapidly ascertain what extraction or fractionation conditions would be most relevant in scaling up the process. In the United States, analytical SFE instrumentation is produced by such firms as Isco, Applied Separations, Leco, and Jasco. In Europe, analytical-scale SFC equipment is available from Berger Instruments, Thar Designs, Jasco, and Sensar. The equipment is obtained from these vendors can be, if needed, slightly modified to study the conditions that are amenable to processing nutraceuticals. King (34) has provided a interesting review of how lab-constructed equipment can be used for both analytical and process development purposes. 

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