Beginner's Guide to SPE

SPE Method Development Summary

SPE Method Development Summary

The following table summarizes the foregoing discussion of the modes of SPE:

Summary of Utility and Practice of Principal LC Modes for Solid-Phase Extraction [SPE]

Reversed-Phase

Normal-Phase

Ion-Exchange

Analyte

Moderate to low polarity

Low to high polarity/neutral

Charged or Ionizable

Separation Mechanism

Separation based on hydrophobicity

Separation based on polarity

Separation based on charge

Sample Matrix

Aqueous

Non-polar organic solvent

Aqueous/ Low ionic strength

Condition/ Equilibrate SPE Sorbent

1. Solvate with polar organic

2. Water

Non-polar organic

Low ionic strength buffer

Preliminary Wash Step

Aqueous/buffer

Non-polar organic

Low ionic strength buffer

Elution Steps

Increase polar organic content

Increase eluotropic strength of organic solvent mixture

Stronger buffers - ionic strength or pH to neutralize the charge

AX

[Anion Exchange]

CX

[Cation Exchange]

Sorbent Functionality

C18, tC18, C8, tC2, CN, NH2, HLB, RDX, Rxn RP 

Silica, Alumina, Florisil, Diol, CN, NH2

Accell Plus QMA, NH2, SAX, MAX, WAX

Accell Plus CM, SCX, MCX, WCX, Rxn CX 

Sorbent Surface Polarity

Low to Medium

High to Medium

High

High

Typical Solvent Polarity Range

High to Medium

Low to Medium

High

High

Typical Sample Loading Solvent

Water, low strength buffer

Hexane, chloroform, methylene chloride

Water, low strength buffer

Water, low strength buffer

Typical Elution Solvent

CH3OH/water, CH3CN/water

Ethyl acetate, acetone, CH3CN

Buffers, salts with high ionic strength, increase pH

Buffers, salts with high ionic strength, decrease pH

Sample Elution Order

Most polar sample components first

Least polar sample components first

Most weakly ionized sample component first

Most weakly ionized sample component first

Mobile Phase Solvent Change Required to Elute Compounds

Decrease solvent polarity

Increase solvent polarity

Increase ionic strength or increase pH

Increase ionic strength, or lower pH

This has been a brief introduction to sample enrichment and purification using solid-phase extraction [SPE]. The best way to start using SPE is to first learn what others have done with analytes and/or matrices similar to those of interest to you. You will find >7,700 references to the use of SPE in the Resource Library on waters.com. Fill in the blank with a partial compound or matrix name in the following search phrase:
“Sep-Pak” OR “Oasis” AND ______*

NOTE: Rather than risk a spelling error, use an asterisk [*] with a root name for best results. Using this same search string, even more references [>60,000] may be found on Google Scholar.

Further reading:

J.C. Arsenault and P.D. McDonald, Beginners Guide to Liquid Chromatography, Waters [2007].

P.D. McDonald and E.S.P. Bouvier, A Sample Preparation Primer and Guide to Solid-Phase Extraction Methods Development, Waters [2001].

Waters, Purity by SPE [2008].

U.D. Neue, P.D. McDonald, Topics in Solid-Phase Extraction. Part 1. Ion Suppression in LC-MS Analysis: A Review. Strategies for its elimination by well-designed, multidimensional solid-phase extraction [SPE] protocols and methods for its quantitative assessment [2005].

In this Primer

Beginner's Guide to SPE

SPE - Sample Enrichment and Purification using Solid-Phase Extraction

Goals and Benefits of SPE

SPE Method Development

SPE Method Development Summary

Related

Oasis Sample Extraction Products
Meet your sample preparation needs, from simple matrix clean-up to more complex sample preparation challenges, with Oasis SPE products. Research our Oasis Solid-Phase Extraction plates and cartridges.

Sep-Pak Sample Extraction Products
Simplify protocols and increase recoveries with Sep-Pak sample extraction cartridges and plates, the most referenced SPE products for GC, HPLC and LC-MS analysis.
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