EON’s Dual Membrane™ Passive Diffusion Sampler (DMPDB™) is the world’s number one PDB for sampling virtually any analyte.

DMPDB™ samplers obtain representative discrete interval samples of nearly any dissolved compound in groundwater without purging or pumping, including; VOCs, SVOCs, Metals, Ions, Cations, Inorganics, and the compounds of emerging concern, 1, 4 Dioxane and PFAS.  Effectively reduce sampling cost and eliminate investigation derived waste at any groundwater sampling site.

DMPDB™ Design Features

  • Two separate semi-permeable membranes around a single sample chamber allow virtually any molecule dissolved in groundwater to diffuse into the DMPDB.
  • Perforated support tube provides strength and maintains sample volume in high ionic groundwater conditions.
  • Semi-permeable LDPE membrane holds deionized water and allows transmission of VOCs into sampler.
  • Large-pore upper membrane allows entry of virtually any analyte into the sampler, for a complete water sample.
  • Built-in connection points facilitate easy attachment to the suspension tether using zip-ties
  • Easy to empty. Just puncture with our “Juice-Box Straw” and empty directly into lab bottle.
  • Filling port for field, lab, or factory filling.
  • 1.75-inch diameter fits 2-inch Schedule 40 wells.
  • Lengths up to 28-inch provide sample volume up to 650-ml.

Why Use the DMPDB™?

  • Sample for a wide range of analytes (not just VOCs).
  • Reduce sampling cost 50%-70% by eliminating field time spent purging and sampling
  • Eliminate the cost of purge-water and investigation derived waste (IDW) disposal.
  • Easy and quick installation and recovery helps in high-traffic areas and for Social Distancing
  • No expensive, complicated, or bulky equipment to purchase, maintain, or mobilize.
  • Obtain depth-specific concentration profiles.
  • Reduce sampling error and improve repeatability.
  • A Greener sampling method. Less disposable material, no batteries, gasoline or waste

How Easy Is It? Fill the DMPDB™ with DI water, attach it to a weighted suspension tether using zip-ties, and lower into the saturated zone in the well screen. Attach the tether to the well cap and secure the well as usual. Recover the DMPDB™ at the next sampling event (minimum 3 weeks residence), decant the sampler contents into lab bottles and send to the lab for analysis. For an added cost benefit- before leaving the well, install another DI water filled DMPDB™ for the next sampling round and eliminate a separate installation trip to the well.  There is virtually no maximum time between installation and recovery.

How Does It Work? The Dual Membrane Passive Diffusion Sampler relies on the same diffusion principles that have enabled the standard PDBs to be highly effective for over 20 years for sampling VOCs. The DMPDB™ utilizes two separate semi-permeable membranes aligned in series to form a single sample chamber. The bottom membrane is identical to the one used in the standard PDB. The upper membrane is hydrophilic and has larger pores to enable a wide range of molecules to diffuse into the sampler.  Molecules that enter the sampler through either membrane diffuse throughout the DI water inside the sampler until concentration equilibrium is reached within the sampler and with the surrounding groundwater. The sampler contents stay in dynamic equilibrium with the groundwater flowing through the well and, if concentrations change in the groundwater, they also change in the sampler over time.