*Patent pending

Scalable Enhanced Plasma Discharge Detector for gas chromatography

The SePdd is a powerful and versatile Epd* detector. It is also a unique detector concept for chromatography application development, with its optional application development kit. Hence, with the support of the Scalable Bulding Block concept, it becomes the perfect instrument for system integrators and OEMs that want to provide tailored applications to their clients. 

Unique features

Based on Enhanced Plasma Discharge (Epd) technology*

Replaces DID, PDID, ECD, FPD, FID, TCD

Simple and easy integration into any lab or process GC

Up to 4 simultaneous optical measurements

Spectral compensation mode for background correction

Fully scalable development kit

ppb to % measurement range

IIoT ready

Multiple measurement modes available

Optical wavelength measuring module

Enhanced Plasma Discharge generator module

Digital Signal Processing (DSP) platform

Mesurement capabilities

Permanent gases

Sulfurs

Alcohols

Hydrocarbons

Green house gases

Moisture

VOCs

Pesticides

Mercaptans

BTEX

Nitriles

Any organic molecule

Chlorocarbons

Aldehydes

Duo, Quattro and the development kit

The SePdd detector has been designed to be easily configurable. It is available in two versions. The Duo (two optical modules) and the Quattro (four optical modules) depending on your targeted application.   

Optical module

The optical module, which contains an optical interference filter,  has been designed to be easily configurable for a specific measurement. Its design allows the optical filter to be easily changed.

 

The SePdd can be ordered pre-configured for a specific application or you can tailored it, based on your own knowledge, to your specific needs by changing the optical interference filter.

SePdd Development Kit

Specifications

Carrier gas

Ar, He, N2, O2, H2 and CO2 

I/O interfaces 

RS-485

Ethernet

Analog output

Carrier gas flow

1 mL/min to

100 mL/min

Operation outlet pressure

Atmospheric

or

vacuum

Operating temperature

5°C to 50°C

Gas connections

1/16"

Power supply

10 watts

Voltage

24 V

Dimensions

82 x 82 x 110 mm

SePdd Duo

Top

view

Side

view

Back view

SePdd Quattro

SePdd Development Kit

Application examples

In this section, some application examples are provided to show the capabilities of the SePdd detector. However, for a full resume of the Epd capabilities, please see our DG-01 (Design guidelines and tutorial).

Trace level permanent gases analysis in helium

Molecules

H2: 92 ppb
Ar: 43 ppb
O
2: 103 ppb
N
2: 127 ppb
CH
4: 77 ppb
CO: 94 ppb

Column

8 ft x 1/8’’ o.d., SS

Packing

Mol Sieve 5A 60/80

Mode

Emission

Carrier

Helium

N2 and Ar trace analysis in UHP O2

Molecules

N2: 37 ppb
Ar: 43 ppb

Column 1

8 f tx 1/8’’ o.d., SS

Column 2

6 ft x 1/8’’ o.d., SS

Column 3

6 ft x 1/8’’ o.d., SS

Packing

Mol Sieve 5A 60/80
Mol Sieve 5A 60/80
ArDSieve 60/80

Carrier

Helium

Mode

Emission

Light hydrocarbons analysis in Oxygen

Mode

Tracer

Carrier

Helium

Column 1

10 ft x 1/8’’ O.D., SS

Column 2

4 ft x 1/8’’ o.d., SS

Column 3

4 ft x 1/8’’ o.d., SS

Molecules

CO: 1.7 ppm
CH
4: 2.7 ppm
CO
2: 4.8 ppm
C
2H2: 2.2 ppm
C
2H4: 3.4 ppm
C
2H6: 2.6 ppm
C
3H8: 2.3 ppm

Dopant

Moisture

Packing

HayeSep    D 100/120 - Mol Sieve 5A* - Mol Sieve 5A*

TM

*Column necessary to separate O2 matrix from CO and CH4

CH4 AND NMHC IN O2/AIR

Molecules

CH4: 1.7 ppm
NMHC: 2.7 ppm

 

NMHC = C2H6 + C3H8

Column 2

4 ft x 1/8’’ O.D., SS

Column 3

4 ft x 1/8’’ O.D., SS

Column 1

3 ft x 1/8’’ O.D., SS

Packing

HayeSep   D 100/120 - Mol Sieve 5A - Mol Sieve 5A

TM

Dopant

Moisture

Carrier

Helium

Mode

Tracer

Enhanced Plasma Discharge (Epd) technology*

The versatility and the precision of the SePdd can be achieved because of our unique Epd technology*. This technology, which surpasses other commercially available plasma technology, is characterised by two main innovative features. 

Stabilising/focusing electrodes*

Resolves plasma source instability (quenching) and hence signal to noise improvement at low concentration.

The electron injection electrodes*

Improves ionisation efficiency with molecular, mix gases backgrounds and impurities (mostly electronegative ones).

Measurement modes

The emission mode allows you to do two types of measurement:

Selective Emission measurement

On this mode, the detector is set to measure the light emitted by a molecule or a chemical group at a specific wavelength. 

  • High molecule selectivity

  • Low cross-interference

  • Better signal to noise ratio (ppt sensitivity)

  • Spectroscopic separation of two co-eluting molecules

Universal Emission measurement

For simple applications where a limit of detection in the region of 50 ppb is sufficient, the universal emission mode is a great alternative

  • Monitor a broad variety of molecule emissions with a single optical module

  • Reduce complexity of the detector

  • Reduce system cost

Tracer measurement

The tracer mode is a variant of the doping mode and exploits the reactor properties of the plasma. In this mode, the doping gas is used as a tracer gas.

 

See our DG-01 document for more details about that mode. 

Power balance

​This mode uses one optical channel. It could be made selective or universal based on the optical filter selected. Under normal conditions, when only carrier gas is flowing into the detector, the plasma discharge is in equilibrium. This mode uses the transfer of energy to the analytes when they enter the discharge to deduct a measurement principle. On this mode, the molecules does not need to be ionised, they only need to disrupt the power balance.

  • Cost reduction

  • Perfect for percentage measurement range

  • Measurement of molecules that are not ionised by plasma discharge

Spectral compensation technology*

  • Unique to our Epd technology* and to our proprietary spectral compensation algorithm*.

  • The result is an unsurpassed measurement precision and simplier chromatographic methods

N2 (2 ppm) in oxygen without spectral compensation

N2 (2 ppm) in oxygen with spectral compensation mode

The SePdd architecture

A quantum leap for gas chromatography application development

The SePdd is the ultimate tool for application development since it uses the versatility of the Epd technology*, the power of the Digital Signal Processing (DSP) platform and that it can delivered with a full development kit.

Use this scalable platform for a specific application and:

  • Select the required building blocks 

  • Select the perfect measurement modes

  • Determine the optimal wavelength by easily switching between up to 4 optical modules

Obtained a tailored and cost-effective detector solution.

1) The Digital Signal Processing (DSP)

Without a well-engineered signal processing platform, even the best sensors can’t perform. Decades of experience in signal processing with the latest technologies are combined in the SePdd-DSP platform.

  • 4 (8 optional) measurement channels

  • Analog gain and offset adjustment

  • High resolution, high speed analog to digital converted - 24 bits resolution @ 50 kHz

  • 4 high resolution chromatogram analog outputs

  • Digital outputs and inputs

  • Advanced signal processing 

    • Signal filtering (window filtering, moving average)​

    • Peak remodeling algorithm*

    • Possibility to generate a compound signal by doing arithmetic with the different measurement channels.

The Digital Signal Processing (DSP)

2) Plasma Discharge Cell

The plasma discharge cell, which is made of premium quartz material and treated with a proprietary process to eliminate fluorescence, contains the plasma discharge and provides the optical measurement windows.

4) Plasma discharge electrodes

The plasma discharge electrodes provide an efficient power coupling to the discharge gas, normally the carrier gas.

6) Electron injection electrodes

The electron injection electrodes provide a supply of free electrons to the plasma zone improving the ionisation process mostly with electro negatives gas or impurities. This current is also controlled by plasma controller and transparent to the users.

8) Sub-atmospheric pump module

In some specific cases, using the detector below the atmospheric pressure will improve peak shape, by virtually controlling the internal volume of the detector, and will also reduce baseline signal and increase emission. Also it eases the process of maintaining a stable discharge of specific gas mixtures.

3) Enhanced Plasma Discharge generator module

This module is the core of our Enhanced Plasma Discharge technology*. It maintains, stabilises and focuses the plasma discharge and controls the different measurement modes.

5) Focusing/stabilising electrodes

A focusing/stabilising and a modulated field is applied to the plasma discharge with these electrodes. This field, which is controlled by the plasma generator module, resolves plasma source instability, hence also improves signal to noise at low concentration.

7) Permeation doping module

There are several situations where the addition of a compound to the carrier gas will improve peak shape or make the detector working in the so call tracer mode. This mode allows to measure several impurities by using only one emission wavelength. Useful for specific hydrocarbons and VOCs measurement. It could also be used for permanent gases measurement.

9) Optical wavelength measuring module

User configurable optical wavelength measuring module. Configurable to be selective for a specific molecule/chemical group or as a universal measurement device.