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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 spe
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
rmp collection methodology
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)
infiltrex vs whole water
Infiltrex vs Whole Water
  • 4L whole water sample vs 100L Infiltrex particulate (filter) + dissolved (XAD2)
bias trend1
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?
alternatives
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