SPE of aqueous amino acids

[MSCHemist]

I am actively working on my GC amino acid method again after having to shift to other priorities.

I am working on a SPE cleanup. The one paper I am following uses 200mg/3ml SCX columns but I don't like their protocol much. They had to condition the column with a lot of MeOH and water then they applied the sample but stated they couldn't do any washes or they lost analyte. They elulted with a mix of MeOH and ammonia. Does anyone have a better protocol. Also I don't have a vacuum manifold so I will be relying on simple gravity flow.

https://www.jstage.jst.go.jp/article/an ... _1285/_pdf

[Don Shelly]

A strong cation exchange should work with rinses.

1. condition with 5 ml methanol
2. equilibrate by flushing with 10 ml water
3. adjust sample pH to neutral or lower
4. load sample by gravity (dropwise)
5. wash with anything you want as long as pH is below 7
7. you need to dry the sorbent at this stage. Try pushing air or nitrogen through the cartridge
8. elute (dropwise) with MeOH at pH 11 - 12. Yes, adjust pH with ammonium hydroxide

UCT has a gravity flow cartridge if you want to try it. The part number is XRBSH515.

Caveat - yes, I work for UCT

Don

[MSCHemist]

Phenomenex has a sorbant packed tip that they use with their Ezfaast kit that you draw the sample into it discharge the matrix then draw in the elution mix and discharge it with the AA's. Is that something that is available? Phenomenex will only sell the whole kit.

[Don Shelly]

That product is most likely made by DPX labs.

http://www.dpxlabs.com/