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SPE sorbents are most commonly categorized by the nature of their primary interaction or retention mechanism with the analyte of interest. The three most common extraction mechanisms used in SPE are reversed phase, normal phase and ion exchange.

This concise diagram is designed to assist you in selecting the proper sorbent for your application. For more detailed information, reference books are available (page 372).

SelectingTheProperPhase

Mechanism TypicalApplication

reversedPhase Extraction of hydrophobic or polar organic analytes from aqueous matrix

normalPhase Extraction of polar analytes from non-polar organic solvents

IonExchange Extraction of charged analytes from aqueous or non-polar organic samples

aqueous

water

ionic

organic

organic

neutral

organic

neutral

nonpolar

reversedphase

strata-X

SDB-L

C18

C8

PH

(+)basic

cationexchange

strata-X-C

SCX

WCX

Screen-C

Screen-C GF

(-)acidic

anionexchange

SAX

NH2

Screen-A

polar**

reversedphase*

strata-X

CN

neutral

moderately**polar

reversedphase

strata-X

C8

CN

non**polar

reversedphase

strata-X

SDB-L

C18

C8

PH

moderatelypolar

normalphase

Si-1

NH2

polar

normalphase

CN

Si-1

FL-PR

NH2

(+)basic

cationexchange

strata-X-C

SCX

WCX

Screen-C

Screen-C GF

(-)acidic

anionexchange

SAX

NH2

Screen-A

ionic

strata-X-AW

strata-X-CW strata-X-CW

strata-X-AW

*NOTE: These can be difficult to extract. Consider non-retentive reversed-phase to remove interference.

Polarity logP

Polar log P<1

Mid-Polar(moderately) log P=1-3

non-Polar log P>3

log P is the partition coefficient that can be used to determine the polarity of a compound

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STRATA® SPE METHOD DEVELOPMENT

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