Solid Phase Extraction Issues

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