Graph Coates flow

Tuncel and Dogrukol-Ak [29] developed a flow-through spectropho-tometric method for the determination of omeprazole in pharmaceutical preparations containing enteric-coated pellets. Sample was dissolved in 100 ml 0.1 M sodium hydroxide and filtered. Portions were analyzed by flow-through spectrophotometry using a Spectrophoresis 100 system with 75 ym fused-silica capillaries with detection at 305 nm. Samples were pumped through the system for 2 min. Results were compared with those obtained by standard spectrophotometry at 305 nm. Detection limits was 8 fiM omeprazole and the calibration graph was linear. The pellet matrix did not interfere. RSD was 1.9% (n = 6). 

As our example we will use data taken from Fig. la of a paper by R. Kieselbach in Anal. Chem. 33 (1961) 23, which shows H as a function of v for air, butane, and cyclohexane, flowing through a gas-chromatographic column (1 m long, 6 mm inner diameter) packed with 35-80 mesh Chromo-sorb coated with 10% Dow-Corning 200 silicone oil. The carrier gas was helium, the column was kept at room temperature, and a thermistor was used as the detector. Table 6.9-1 lists the data as estimated from the graph. 

A crystal coated with poly(4-vinylpyridine) was used for the determination of copper (11) in solution (100). Metal ions adhering to the resin were removed by passing 1 mM EDTA solution through the cell. The frequency change resulting from the sorption of copper was linearly proportional to the flow rate of copper solution up to 8 ml min", and to the volume of the solution that passed over the crystal over the range 1-7 min. The calibration graph was linear... 

The graphs show a comparison of the DoO versus air flow at a constant time of re-oxidation and time of re-oxidation at a constant air flow rate for cells based on 1.5 and l.O nun Coat-Mix substrates at 800 and 600°C. The curves at 800°C take a significantly different course, whereas no difference can be observed at 600°C. 

---