Solid Phase Extraction (SPE) Method by Retention Mechanism

Each SPE mechanism/phase has a general set of solvent conditions under which SPE may be performed. Use the solvents/pH conditions listed below, volumes as determined in Method and Sorbent Volume Selection.

Reversed-Phase SPE Method

SDB-L, C18, C8, PH, CN, X, XL Sorbents
Analyte Properties	Low to moderate polarity (or nonpolar) Hydrophobic Neutralized/uncharged	Pharmaceuticals, Pesticides, Herbicides
Sample/Matrix	Aqueous, diluted with buffer	Biological fluids, Water
Conditioning Step	Solvation – polar organic solvents Equilibration – aqueous, buffers	Methanol Water or buffer
Wash Step	Aqueous buffers with 5 to 50 % polar organic solvent	Methanol: Water (5:95)
Elution Step	Polar or non-polar organic solvent(s) with or without water, buffer and/or strong acid or base	Methanol: Acetonitrile (50:50)

Normal Phase SPE Method

Silica, Florisil®, NH2, CN
Analyte Properties	Moderate to high polarity compounds (neutralized/uncharged)	Pesticides
Sample/Matrix	Non-polar organic solvents or moderately polar organic solvents	Hexane, chloroform, petroleum ether, toluene or methylene chloride
Conditioning Step	Solvation – polar organic solvents (optional) Solvation – polar organic solvents (optional) Equilibration – sample/matrix solvent	Methanol (optional) Hexane or chloroform
Wash Step	Non-polar organic solvents with a low concentration (1 to 5 %) of moderate to low polarity organic solvents	Hexane with 1 % THF, ethyl acetate, acetone, acetonitrile or IPA)
Elution Step	Non-polar organic solvents containing higher concentrations (5 to 50 %) of moderate to high polarity organic solvents	Hexane with 10 % THF, ethyl acetate, acetone, acetonitrile or IPA

Strong Ion-Exchange SPE Method

Anion exchange: Screen-A, SAX, X-A, X-AW, XL-A, XL-AW Cation exchange: Screen-C, SCX, X-C, X-CW, XL-C, XL-CW
Analyte Properties	Aqueous; Low ionic strength buffers ( > 30 mM), pH adjusted	Biological fluids plus buffer
Sample/Matrix	Non-polar organic solvents or moderately polar organic solvents	Hexane, chloroform, petroleum ether, toluene or methylene chloride
Conditioning Step	Conditioning – polar organic solvents Equilibration – low ionic strength buffers, pH adjusted	Methanol 25 mM Tris-OAc, pH 7
Wash Step	Aqueous buffers of low salt concentrations with or without organic solvent	Anion exchange: Buffer pH 7: Methanol (50:50) Cation exchange: Buffer pH 6 1 M acetic acid Methanol
Elution Step	Neutralize the charge on the weak anion or cation Increase the ionic strength and counter ion concentration Add a strong counter ion displacer	Anion exchange: Hexane: ethyl acetate (75:25) +1 % glacial acetic acid Cation exchange: Methanol + 5 % NH3

NOTE: These are general starting conditions. Please contact your Phenomenex technical consultant for more assistance.

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