Inhibitor Screening: The Static Flask Test
By: Michelle Elliott 10/8/03
Updated 06/27/08 by Adelon Agustin
Screening of inhibitors is done to determine the effectiveness and efficiency of experimental inhibitors under aerobic and anaerobic atmospheres. Inhibitor testing can be done using two different methods: Static Flask Test or use of the CSTR. When using the CSTR, consult the operator’smanual. This procedure explanation only covers the Static Flask Test.
This test is based on a small scale and usually the first test done on an experimental inhibitor. It will provide an answer to whether or not further testing is needed.
|2 three-necked round bottom flask (50ml) |2 Mass flow meter for nitrogen |
|2mini magnetic stir bars, placed in the flasks |Heating Mantle |
|6 rubber septa, to fit the round bottom flasks |Stirring Mantle, with large stir bar |
|2 Syringe Needles, 20 gauge, 6 in long, luer hub and deflecting |Temperature controller, with thermocouple ||tip |Glycerol |
|2 needles, 21gauge, 1in long, used to vent the flasks |Metal pan |
|2 glass syringes, 5cc with 18 gauge, 4 in detachable needles |Clamps|
| |Hoses with adapters |
| |6 ml vials with non-septa caps |
| |Ice bath|
A. Preparing Sample
1. The sample should be prepared as to Project Initiation. Normally the sample solution consists of 150ppm of experimental inhibitor in TBC free Styrene. This test compares the experimental inhibitor to standard DNBP. The DNBP also needs to be prepared at the same concentration as the experimental inhibitor.2. TBC free Styrene is obtained by taking plant Styrene and filtering it over Silica pellets.
a. Fill a seperatory funnel with silica pellets.
b. Pour ~50 ml of Ethyl benzene (EB) into the funnel over silica pellets. Let sit for a couple of minutes, then drain. The EB activates the Silica pellets.
c. Fill the funnel with Styrened. Open the valve of the funnel and adjust to allow a drip rate of 1 drop per 5 seconds. Let styrene drip run for a few milliliters before collecting in solution flask in order to remove traces of EB. The slow drip ensures the removal TBC from the Styrene. (Note: as inferred, the process of preparing TBC free styrene is time intensive. It would be prudent to set up the filtration process theafternoon before and allow the drip to proceed overnight, ensuring a fresh batch of TBC free styrene the following day.)
e. A GC analysis of the TBC free Styrene should be run to make sure there is no TBC.
3. The experimental inhibitor usually comes dissolved in a solvent (normally EB). The experimental inhibitor is mixed with the TBC free styrene in order to create asample. One idea is to make 100 g of the Styrene/inhibitor mixture (based on the weight percent composition of the inhibitor), making it easier to calculate the concentration and leaves a useful surplus of sample in case additional testing is needed. Make sure that all measurements are weighed and recorded.
1. Oil Bath – The heating of the oil bath takes a...
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