Sample Prep/ Concentrating the Sample

C18 silica gel

• http://www.materialharvest.com/welcome/silica_products/functional_and_reverse.html
• https://tools.thermofisher.com/content/sfs/gallery/high/89870-001-C18-Columns.jpg
• http://www.mn-net.com/Portals/4/images/Redakteure_Chroma/HPLC/C18-Pyramid-3D.gif

suppliers

• http://www.silicycle.com/products/functionalized-silica-gels/chromatographic-phases/reversed-phases
• https://www.sorbtech.com/chromatography/adsorbents/silica-gel/

DIY versions...

Separation Methods for Waste and Environmental Applications By Jack Watson (not enough detail here: packets of silica gel (desiccant, in nori-packets, to keep moisture out) - heated to “sufficiently high” temperatures will lose its -OH groups and “become hydrophobic")

Check out::: HYDROPHOBIC fumed micro silica - THIS IS NOT dessicant

• http://www.theflyfishingforum.com/forums/general-discussion/345179-fly-floatants-noobies-what-floats-your-fly-print.html

"Micro silica is hydrophilic so it is treated with siloxane or silicon oil to make it markedly hydrophobic. These treated powders will float a bead-head fly because their chemical bonds actively repel water." aka Floatants :: seems like fishing stores and archery shops (to keep the feathers of the arrows from getting wet) carry this stuff

my suggestion to try:

1. wash everything you will use with acetone (or nail polish remover) -POLYSTYRENE will melt, polypropylene (eppendorfs, pipette tips, etc. won’t) glass containers may be good, but the seal may melt, etc.
2. make a column with this stuff Floatants -  http://www.chemistryviews.org/details/education/2040151/Tips_and_Tricks_for_the_Lab_Column_Packing.html
3. pour acetone - (nail polish remover) and see if it degrades/dissolves - this is washing the Floatants  with the solvent that would eventually use to wash off your estrogen
4. see if after acetone, it maintains hydrophobicity (repels water= i.e. pour some bottled water on it, and see if the water rolls off)  then it’s good to go - this is to check if the “hydrophobic” material on the silica gel is also washed off with acetone…you don’t really want extra hydrophobic stuff coming off - commercial C18 silica gels have hydrophobic alkanes chemically bound to the gels, so they don’t come off
5. take 1 part acetone-washed Floatants gel, 9 parts of your river water, shake it up for some time (ask Urs to make you a shake-it-baby - well, something that keeps the Floatants suspended) - like some hours, or over night
6. then centrifuge down the Floatants (or let it settle)
7. pour out the river water (keep it in case!)
8. add a small amount of acetone and shake it vigorously
9. take the acetone out (pipette) and put it in an acetone-pre-washed eppendorf
10. repeat 8, and pool into 9
11. your negative control would be the same total volume of your acetone (to make sure your nail polish remover doesn’t have some steroids in it)
12. air dry the acetone in the eppendorfs - now you should have a concentrated hydrophobic compounds from river water
13. you can dissolve this in tiny amounts of DMSO and try your YES assay