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Solid Phase Extraction Issues

Solid Phase Extraction Issues. TRC September 2007. Solid Phase Extraction (SPE). Provides a means for preconcentrating water phase organics to allow lower detection limits without logistically intimidating sample sizes (~20L equivalent per analyte type- PCBs, PAHs, etc)

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Solid Phase Extraction Issues

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  1. Solid Phase Extraction Issues TRC September 2007

  2. Solid Phase Extraction (SPE) • Provides a means for preconcentrating water phase organics to allow lower detection limits without logistically intimidating sample sizes (~20L equivalent per analyte type- PCBs, PAHs, etc) • May show some artifacts of incomplete recovery, depending on a number of factors, e.g. DOC, sample size, collection speed

  3. RMP Collection Methodology • 100L sample, pumped at 1.5L/min by Infiltrex 300 through wound glass filter (nominal 1um pore) and columns (2x70g) of XAD2 resin. • Most recent cruise increased volume pumped through filter to increase PBDE signal relative to blanks (no change in pumping speed)

  4. Infiltrex vs Whole Water • 4L whole water sample vs 100L Infiltrex particulate (filter) + dissolved (XAD2)

  5. 2004

  6. 2005

  7. Bias Trend?

  8. Bias Trend? • Does not track TSS (SSC) • 4L (liquid-liquid) solvent extraction recovery high for low organics (=totPCBs) • 100L short contact time = lower recovery? • 100L solid phase extraction high(er) for high organics samples • 4L solvent volume = limited equilibrium?

  9. Alternatives • Switch to liquid-liquid extraction • Likely accurate for low organics • Underestimate for high concentrations • PCB/PBDE, PAH, OCP, OPP, backup = 4L x 5 bottles/site x 22 sites = 110 bottles, 440L to ship • Status quo 100L SPE- (preferred?) • Maintain awareness of tendencies • Considered minimum concentrations • More accurate for high concentration samples

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