Presentation on theme: "Solid Phase Extraction Issues TRC September 2007."— Presentation transcript:
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) May show some artifacts of incomplete recovery, depending on a number of factors, e.g. DOC, sample size, collection speed
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 4L whole water sample vs 100L Infiltrex particulate (filter) + dissolved (XAD2)
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 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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