Sensing Technologies | Epd


A quantum leap for gas chromatography sensing

The Epd (Enhanced Plasma Discharge) is a gas detector technology based on a stabilised dielectric barrier discharge (DBD) plasma. The breakthrough is down to the focusing and stabilising compound electrodespatent pending which generates a more stable plasma discharge across a broad range of operating conditions. It uses the highly energetic plasma behaviours to perform measurements. Its versatility and sensitivity makes it a technology of choice to measure molecules with high ionisation potential such as the permanent gases as well as molecules with lower ionisation potentials such as VOCs, Hydrocarbons and sulfurs from ppt to % range.

  • Replaces DID, PDHID, ECD, FPD, SCD, FID, TCD, Mass Spectrometer and former PED technologies
  • Epd technology available in various configurations to suit your application and chromatographic conditions.
  • Unique compound electrodepatent pending that can withstand high temperature and high pressure
  • Multiple measurement modes available
  • ppt to % measurement range
  • Selective or universal
  • Compatible with argon, helium, nitrogen, oxygen, hydrogen carrier
  • Work also at sub-atmospheric pressure

Epd Products

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Measurement capabilities

  • Permanent gases
  • Hydrocarbons
  • VOCs
  • BTEX
  • Chlorocarbons
  • Sulfurs
  • Green house gases
  • Pesticides
  • Nitriles
  • Aldehydes
  • Alcohols
  • Moisture
  • Mercaptans
  • Any organic molecule

Technology principles

Stabilised Dielectric Barrier Discharge (DBD)

At the core of our Epd technology, a highly energetic plasma source is used to ionize molecules. The unsurpassed performance is down to the Epd stabilised dielectric barrier dischargepatent pending. The DBD isolates the discharge electrodes from the ionised plasma, avoiding sputtering, cell inner wall coating and analyte interference.

Compound electrode patent pending

The major breakthrough comes from our innovative compound electrodepatent pending. By nature, DBD generates streamer discharges. This results in a noisy signal impacting signal to noise ratio. The enhancement of our technology compared to other DBD or plasma emission detector (PED) is related to the stabilisation and electron injection electrodespatent pending (here embedded in the compound electrode). The electrode improves stability by sweeping away the accumulation of charges on the inner surface wall.

The unique compound electrode technology also provides other benefits such as:

  • High temperature operation
  • High pressure operation
  • Adjustable discharge gap
  • Higher ionisation potential and efficiency

Epd controller/driver

The compound electrode on its own is unique. However, the level of performance achieved by the Epd could not be reached without a close control of various parameters that are affecting discharge power distribution. This is the purpose of the Epd controller/driver.

  • Force driven plasma discharge signal. Improve plasma stability compared to other plasma sensing technology
  • Adaptive control of driving voltage and frequency
  • Stabilisation field automatically controlled

Measurement modes

The Epd technology uses various plasma characteristics to generate a sensing signal. The various modes involve the use of one or more optical measuring devices known as Optical Wavelength Module (OWM).

Direct emission: In this mode, the OWM is configured with an optical filter to measure the emission of a specific molecule or chemical group.

Tracer mode: In this mode, the OWM is configured with an optical wavelength to monitor the reaction of molecules with a tracer gas. For example, O2 emission line reduction from the combustion of hydrocarbons with O­2. Alternatively, CO2 by-product emission could be monitored.

Constant power mode: This mode of use is a basic mode and uses only one optical channel. The idea behind this concept is to maintain constant the emission intensity when an impurity peak is going through the cell.

 It also allows real time compensation of the tailing peak and drifting baseline by adjusting the discharge field in order to reduce the effect of the residual charges in the discharge gap.

Advanced measuring mode with CPM platform

When used with our advanced CPM platform, the Epd technology provides a very powerful tool set for chromatographers. An example is the spectral compensation mode. As this is unique to our sensing technology which is a spectroscopic detector, multiple spectral signal can be merged together into our advanced algorithm to cancel matrix interferences, cancel baseline drift, sum wavelength, etc…

This is one of the many benefits. Other benefits are:

  • Advanced signal filtering algorithm
  • Event tables to optimise parameters for each peaks
  • Peak remodelingpatent pending
  • Arithmetic unit
  • Analog gain and filtering
  • High speed, high resolution sampling
  • Power balance mode automatic control