Botany lab 13 Chromatography failure

The Chromatography laboratory failed spectacularly. 

Every single plate, with three different plate types, looked like this. The solvent above was 70% ethyl alcohol. The pasty white appearance is likely a result of too much calcium carbonate. 

Most of the class used 91% isopropyl alcohol with a result seen as above. Ethyl alcohol was used successful last year. 70% isopropyl alcohol was also used successfully last year. 

Perhaps the plant leave mix was problematic. Alternanthera sessifolia was the dominant plant in the mix. Some Codiaeum variegatum and Cordyline fruticosa leaves were added in. Last year only Alternanthera sessifolia was used. Was that contributory to the issues?
 
The calcium carbonate was locally sourced. Was too much added? Not enough? About a half to one teaspoon was used. Perhaps there were impurities in the calcium carbonate.

The use of an eye dropper tended to create larger blobs, but no movement of chlorophyll was visible on any plate. 

Santriko grinding the leaf mix as Sweethy and Susan onserve

Was something about this process amiss? Iso-octane was not available, and acetone as a pigment driver last year was deemed a failure. Acetone was used last year during the grinding process, this year 91% isopropyl alcohol was used during grinding. Return to acetone?  Try automotive octane boosters that might work? One of the original bottles of solvent remains intact and the bottle was a mix of acetone and iso-octane.

Susan takes over grinding the leaves

Should the leaves be pulped in a blender first? 

Some of the support material are in the lab 13 plastic container.

Beverly with one of the newest paper strips

The solvent front is most visible with strong backlighting.


One group marked their plate with blue ink which proved very mobile.

The results were not as hoped for.

Board notes. Going back and rereading procedures will be necessary to try to determine the cause of this failure. A return to use of Alternanthera sessifolia is one option that stands out as needing exploration. The return to acetone in the grinding mix should not be ruled out. The glass plates continue to be more problematic. Capillary tubes would produce fewer blobs. Are there other plants that should be considered? Procedural changes? The Alternanthera sessifolia was fresh cut, which should have enhanced the results. What was missed or overlooked? 

Answers are coming through in the clean-up and post-mortem.

The less water, the better. 

While acetone failed as a pigment driver last year, acetone should have been used during the extraction phase. Clean-up was tough: the liquid dried to cement. Too much calcium carbonate. O.5 grams is a very small amount. About 1/12 of a teaspoon for 5 grams of leaves. As with most failures and accidents, failure to brief on the procedure led to the disaster. In this case the fault lies with the instructor.  

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