Hey all. So I have to find a larger processing solution until I officially start prototyping my own custom ones. Right now we have a .5kg repackable column, we are using with both florisil (magsil) and silica gel.
I plan on only using silica gel, as we have proven it can remediate our pesticides effectively if we use enough of it, and it is pretty simple to clean for reuse.
So we are looking at 5L columns and larger.
I was thinking of getting some regular SS extraction columns, with filter frits (near 10u size). I was gonna put some lids on there with respective luer locks for processing and swagelocks for loading. Going to load the silica as a slurry, top does not need compression, just an even level. We can even add a small sand layer if needed. The one issue I was encountering with initial brainstorming is even solvent pressure dispersal/distribution along the top frit/layers. I don’t think using a frit/filter (even at 10u) alone will disperse the solvent well enough along the top layer/level. A few fabricators told me it should be fine, but I’m still a little weary.
Unloading the silica is planned to be pretty easy. After air purging with the device to dry the silica, we open the top filter/lid and then open the bottom one over a bucket we plan to clean/wash the silica in. We then use a large ram rod to push the silica patty out the column into the bucket.
Ran across this quote about the invention of LC and found it chuckle worthy:
“It was invented and used for the first time by Tswett, a Russian botanist, in the early 1900’s to separate plant pigments on a column of calcium carbonate [1].”
I always had trouble loading as a slurry though it is done all the time. One way to pack it with a 100% success rate is to load the dry silica into a very clean and dry column. You need a vacuum pump. Load the silica up past the desired level a bit if possible. Then take a hand held massage device and let it rattle against a structural part of your rig. I hold it on the clamp. Then once it is fully vibrating hit the vacuum pump full on from the outlet port and you will see an insta-pack action happen.
At that point then with vacuum still pulling a large dowel is used to pack by hand all around the top. Then a bent spatula is used for the trouble area (the edges) and packs it once tightly down all around the edge of the column by hand. Takes about five minutes.
Then at that point make sure you have enough of the solvent system you plan to use to easily fill the column of gel and some more to boot. With vacuum still running pull the solvent all the way through the column until dry and make sure the entire column at one point at least is swamped in solvent. Pull dryish and now the column is packed. Protect the top with at least a paper lab filter or if large a sand layer so solvent does not churn the gel at all when added. Very impotant.
The technique is pretty fast and has not failed. A slurry is also an art form but it is one I did not master. Bubbles caused me grief.
How did your Chromatography work for removing pesticides. I have 100’s of kilograms of disitilite that need extensive pesticide remediation. Were looking at many systems including the Biotage but everyone has a 3+ month lead time. What system and procedures worked best? Can you or do you know anyone can handle our needs for remediation for a fee in the meantime? Thanks…
As someone else correctly remarked elsewhere, some pesticides are easier to remediate than others, and there are physical (chromatography) and more specialized chemical (base wash, acid wash, etc.) methods available. I think the usda website even has some of the methods posted.
Did you get your material tested ? Do you have a coa ?