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- Posts: 15
- Joined: Wed May 29, 2019 4:45 pm
- Location: New York City Area
I am trying to use SPE to concentrate river water (4L) to a high enough concentration that I can quantitate pharmaceuticals using GC-MS. The drugs I am looking at are estrogenic hormones (E1, EE2, E2, E3). However, before I can go out to get samples I am trying to verify my SPE-GC-MS method, and am having trouble with recovering my analyte.
To do this I am spiking ultra-pure water with one estrogen (E2) as a test at the concentration of 500ng/L. After SPE extraction my GC-MS is telling me that I only have about 35% of that. To make sure the GC-MS method worked, I tested the stock today and got the correct value.
Here is how I am doing the SPE:
Cartridge: C18, 0.5g, 3mL
Pretreatment: MeOH (4mL), EtOAc (4mL), and H20 (4mL)
Flow: ~7.5mL/minute using a Vaccum Manifold
Elution: MeOH (12mL)
Drying: Vaccufuge (7.5 hrs, 45 Deg C)
Reconstitution: Pyridine (1mL)
Thank you,
Troy