Phase separation collection design

The HPLC-FTIR technique has recently been used to identify six catechins and two methyl-xanthines present in green tea extracts." " A reversed-phase separation of the compounds was performed on a C-18 column equilibrated at 30°C using an isocratic mobile phase of acetonitrile-0.1% formic acid (15 85), prior to introduction to the deposition interface linked to the FTIR detector. The solvent was evaporated at 130°C and spectra were collected every 6 sec during the run. Two distinct designs for HPLC-FTIR interfaces have been developed flow cells and solvent elimination systems. Flow cell systems acquired spectra of the eluent in the solvent matrix through IR transparent, nonhydroscopic windows. The... 

The use of precision density measurements for monitoring polymerization reactions can be done rapidly and automatically using commercially available instrumentation. The method is independent of the reactor size and design but suffers from sampling difficulties. The examples of this paper show the rapidity of data collection and three distinct sampling problems pump failure from either monomer attack or polymer scale formation, monomer phase separation in the density cell, and the lag time for rapid polymerizations. Techniques have or can be devised to avoid or reduce the influence of these problems. 

In a setder the continuous phase is assumed to move vertically upwards or downwards from the inlet to the outlet in a uniform plug flow. At the interface the continuous phase velocity is ( /Aj, where Aj = L x (interface width) is the interface area. The width of the interface depends on its location in the settler. If droplets settle (or rise) faster than the continuous phase velocity, the droplets will be collected and the phases will be separated. Thus, design so that... 

QA is an important aspect of any technical study. It is particularly crucial in an LSMBS, because several hundred participants, widely separated geographically, are involved. The analytical laboratories typically have standard provisions for QA inspections and reviews, and the field phase management organization is also likely to have standard provisions for QA inspection and review. Shoppers, however, are typically external to study management and analytical laboratories and, thus, are not directly covered by existing QA systems. The study design must include a means by which the field phase, i.e., sample collection and shipment by the shoppers, is made to comply with QA requirements. 

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