Columns automatic

A stainless steel column (4.6 mm internal diameter by 250 mm length) packed with 7 micron Zorbax ODS (Dupont) was equilibrated with 82 % Acetonitrile in water at a flow rate of 2.0 ml/min. provided by a Spectra Physics Model 87(X) pump and controller. The effluent was monitored at 230 nm using either a Tracor UV-Visible detector Model 970A or a Jasco Uvidec UV detector Model 1(X)-V. Peaks were recorded and calculated on a SpectraPhysics recording integrator. Model 4200 or Model 4270. Samples of 0.5 mg/ml in toluene were applied to the column automatically with a Micromeritics Autosampler Model 725 equipped with a 10 pi loop. 

Since it is easily possible to change columns automatically with the aid of selection valves, it appears that an approach involving a minimum of two colums (one for NPLC and one for RPLC) is generally to be preferred. 

Apparatus Gas chromatograph with flame ionization detector (Flewlett-Packard 5890 Series n, or equivalent) equipped with a 5- xL syringe for 0.32-mm (id) columns. Automatic sampler (HP 7673, or equivalent). Chromatographic data system or integrator (HP 3365 Series II software, or equivalent). Retention gap, deactivated fused silica, 1-mm x 0.32-mm (id) with capillary column connectors. DB 5-HT,... 

P16. Perry, T. L., Stedman, D., and Hansen, S., A versatile lithium buffer elution system for single column automatic amino acid chromatography. J. Chromatogr. 38, 460-466 (1968). 

Control modifications The control system can be modified to avoid opening the heat input control valve in case of a failure. Two incidents have been reported (414) in which the column automatic control system opened the heat input control valve during a coolant failure. In each case, the relief requirement was substantially greater than it would have been had the heat input controller stayed at its initial opening. In both cases, heat input was controlled by column AP (Fig. 9.4). Problems may also occur when heat input is controlled by bottom or reflux drum level. 

Atmospheric air can be injected into a chromatographic column automatically, directly into the place where analysis is performed, with the use of portable chromatographs. In this case, injection is done by means of sampling valves into which air is pressed or sucked. Air can also be injected into a chromatographic column with a gas-tight syringe prior to its direct uptake from the atmosphere. 

Gases in installations and technological systems are under pressures that are usually different from the atmospheric pressure and can be injected into a chromatographic column automatically or manually by means of sampling valves or manually with syringes. 

SPE (Vim-DVB, Oasis HPB, Lichrolut EN)-column. Automatic SPE (Hysphere Resin GP, PLRP-S)-cartridges. Automatic (Prospekt-2)... 

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An extraction plant should operate at steady state in accordance with the flow-sheet design for the process. However, fluctuation in feed streams can cause changes in product quaUty unless a sophisticated system of feed-forward control is used (103). Upsets of operation caused by flooding in the column always force shutdowns. Therefore, interface control could be of utmost importance. The plant design should be based on (/) process control (qv) decisions made by trained technical personnel, (2) off-line analysis or limited on-line automatic analysis, and (J) control panels equipped with manual and automatic control for motor speed, flow, interface level, pressure, temperature, etc. 

Distribution of the scoured wool to the cards then occurs. This is often done using a combination of pneumatic and mechanical transport systems, usually with the provision of accumulator bins that hold a few hour s production. Modem cards are usually fed with tower feeds, which automatically control the height of the wool column. 

Distillation columns are controlled by hand or automatically. The parameters that must be controlled are (/) the overall mass balance, (2) the overall enthalpy balance, and (J) the column operating pressure. Modem control systems are designed to control both the static and dynamic column and system variables. For an in-depth discussion, see References 101—104. 

Perfluorobutyric acid [375-22-4] M 214.0, m -17.5", b 120"/735mm, d 1.651, n 1.295, -0.17. Fractionally distd twice in an Oldershaw column with an automatic vapour-dividing head, the first distn in the presence of cone H2SO4 as a drying agent. 

General. With simple instrumentation discussed here, it is not possible to satisfactorily control the temperature at both ends of a fractionation column. Therefore, the temperature is controlled either in the top or bottom section, depending upon which product specification is the most important. For refinery or gas plant distillation where extremely sharp cut points are probably not required, the temperature on the top of the column or the bottom is often controlled. For high purity operation, the temperature will possibly be controlled at an intermediate point in the column. The point where AT/AC is maximum is generally the best place to control temperature. Here, AT/AC is the rate of change of temperature with concentration of a key component. Control of temperature or vapor pressure is essentially the same. Manual set point adjustments are then made to hold the product at the other end of the column within a desired purity range. The technology does exist, however, to automatically control the purity of both products. 

A more sophisticated method, giving a much more detailed characterization, involves the on-line coupling of EC and GC (LC-GC). Analysis schemes for middle distillates (kerosine, diesel and jet fuels) combining EC and GC have been reported by various authors (25-31). However, only Davies et al. (25) andMunari et al. (27) have reported on the required automatic transfer of all of the individual separated fractions from the EC unit the GC system. Davies used the loop-type interface and Munari the on-column interface. Only Beens and Tijssen report a full quantitative characterzation by means of LC-GC (31). 

The combined acetone extracts were extracted six times with one-fourth volume of ethylene dichloride and the ethylene dichloride extract was evaporated under vacuum to leave the steroid residue. This steroid residue was taken up in a minimum of methylene chloride and applied to the top of a column packed with 30 grams of silica which had been previously triturated with 21 ml of ethylene glycol. Then various developing mixtures, saturated with ethylene glycol, were passed over the column. Cuts were made as each steroid was eluted as determined by the lowering of the absorption of light at 240 mp on the automatic chromatographic fraction cutter. 

Vehicles (external) Buffer rails, ramps Transporters (internal) Bollards, route demarcation, column base plinths, guide rails, Ilexible/automatic doors... 

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