Apparatus flow cell

Cell system Apparatus Flow regime Response indicator Growth/Non-Growth References... 

Flow Experiments. The main components of the experimental apparatus are illustrated in Figure 2. The most important component is the glass flow cell, shown in detail in Figure 3. 

Nicklasson M, Langenbucher F. Description and evaluation of the flow cell dissolution apparatus as an alternative test method for drug release. Pharm Forum 1990 16(3) 532-537. 

Fig. 5.10 Computer-assisted extraction kinetics-measuring apparatus for highly stirred phases (A) high-speed stirrer (B) stirrer shaft (C) sample inlet (D) Teflon stirring har (E) Teflon phase separator (F) water hath (G) flow-cell (H) spectrophotometer (I) peristaltic pump (J) chart recorder (K) A/D converter (L) clock (M) minicomputer (N) dual-floppy disk drive (O) printer, (P) plotter. (From Ref. 16.)...

A dissolution testing apparams consists of a set of six or eight thermostatted, stirred vessels of an established geometry and volume from the USP guidelines. The dissolution apparatus provides a means to dissolve each sample, but does not provide a means to determine the concentration of the aetive ingredient in the bath. In the most well-established scheme, sipper tubes withdraw samples from each dissolution vessel and send them through a multiport valve to a flow cell sitting in the sample chamber of a UV-vis spectrophotometer. In recent years, moves have been made to make in situ measurements in the dissolution baths by means of fiber-optic probes. There are three possible probe implementations in situ, down shaft, and removable in situ (see Table 4.2). 

One of the mayor drawbacks is that only volatile and temperature-resistant compounds can be investigated. Gases are magnetized faster than liquids, because they have shorter spin-lattice relaxation times (T ), due to an effective spin rotation mechanism. Therefore, pulse repetition times in flow experiments can be in the range of 1 s and some dozen transients can be accumulated per separated peak. Nevertheless, the sample amounts used nowadays in capillary GC are far from the detection limit of NMR spectroscopy, and therefore the sensitivity is low or insufficient, due to the small number of gas molecules per volume at atmospheric pressure in the NMR flow cell. In addition, high-boiling components (> 100 °C) are not easy to handle in NMR flow probes and can condense on colder parts of the apparatus, thus reducing their sensitivity in NMR spectroscopy. 

Schematic diagram showing the integration of a polarization modulated birefringence apparatus within a laser Doppler velocimeter. This shows the side view. L light source (a diode laser was used) PSG rotating half-wave plate design LS lens FC flow cell (flow is into the plane of the figure) CP circular polarizer D detector 2D-T two dimensional translation stage 3D-T three dimensional translation stage LDVP laser Doppler velocimeter probe.

There are also special cells for use with USP Apparatus 4 in a closed-loop configuration. Using a 100 mL bottle, a total volume of dissolution media ranges from 25 to 100 mL. For very low volume assembly, a test tube with a rubber stopper allowing for inlet and outlet tubing can be used. However, with the need for even smaller volumes, internal modifications should be made to the apparatus to minimize the impact on functionality due to a change in the internal tubing volumes. Also, the additional volume of the flow cell must be considered. For example, the implant... 

Testing apparatus should be designed to minimize band spreading external to the column (e.g., short, narrow connecting tubing between the column and injector and detector, low dead-volume detector flow cell, etc.). 

Figure 8 (Top) Electrochemical flow cell for the oxidation of phenol and aniline (a) Pb anode feeder (b) packed bed of 1-mm lead pellets (c) stainless steel cathode plate (d) Nation membrane (e) stainless steel screen (f) Luggin capillary (g) glass beads (h) gasket (i) reactor inlet (j) reactor outlet. (Bottom) Schematic of apparatus (a) electrochemical reactor (b) peristaltic pump (c) water bath (d) heater (e) anolyte reservoir (t) gas sparging tube (g) C02 adsorbers. (From Ref. 39.)... 

There are two principal types of apparatus design. One is based on limited volume that is constrained to the size of the container used. The second type uses a continuous-flow cell to house the dosage form and permits constant replenishment of the dissolution fluids. 

Sulphates. Modifications to the automated photometric method for the determination of sulphate, which is based on decreasing the blue colour of the Ba-methylthymol blue complex by the precipitation of barium sulphate, have permitted150 determinations of 0—1.0 mg of SOT 1 with a 1.7% relative error. A flow cell was used with a high flow rate, produced by adding MeOH to the sample stream. A flow apparatus has also been used151... 

Addition funnel pressure reactor, 201 Adjustable pressure relief valve, 200 Aerial oxidation, 64 Aerobic product transfer, 193 Aerosol pressure vessel, 198 Air-sensitive materials decomposition, 147 HPLC analysis, 24 recovering, 193 synthesis and handling, 34 Alkyne electron density, 287 Alkyne ligand, 282 Alkyne it donor orbitals, 287 Alkyne levels, 285 Ambient pressure flow cell, 238-244 Ammonia synthesis, 182 Anaerobic column chromatography, 17-18/ Anaerobic transfer, 144 Anionic polymerization, 182 Apparatus design philosophy, 117 Arc lamp... 

Fig. 2. Continuous flow apparatus Adapted from (21). The flow cell was maintained at a fixed temperature. The circulating peristaltic pump was typically run at f mL/min flow rate. A LabView program running in the PC helped with data collection and analysis.

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