Defiant’s Cutting-Edge Technology

Defiant Technologies has been providing affordable, innovative chemical detection systems since 2005.

How can we make our FROG Portable Gas Chromatograph GC so small? Let’s take a look inside.

COLLECT

Micro-Preconcentrator

The MEMS micro-Preconcentrator from Defiant collects VOCs into a highly porous glass-like material called a xerogel.

The preconcentrator die has a series of fins etched on the bottom side of the die and a resistive heater is patterned on the top. The xerogel, deposited on the fins, is very high capacity.

After collecting VOCs for a defined period of time, the heater is energized, heating the xerogel to thermally desorb any analytes it collected, and they are pushed into the GC column as a sharp pulse. In this fashion, the preconcentrator also acts as the injector for the system.

SEPARATE

Micro Gas Chromatographic Column

Defiant’s high aspect ratio MEMS GC column is coated with a polymeric stationary phase.

As the sharp pulse of analytes from the preconcentrator are pushed through the GC column by the carrier gas, the analytes partition into and out of the stationary phase. The rate at which analytes partition in and out of the phase is what causes the analytes to separate.

The amount of time it takes for an analyte to traverse the column is called the retention time, which is characteristic of a particular analyte.

DETECT

Miniature Photoionization Detector (PID)

After the analytes are separated by the GC column, the analytes enter the detection stage.

The photoionization detector (PID) ionizes the molecule and the electron liberated by the UV photons from the lamp are counted at an electrode.

That count is translated to a graph with each compound showing as a distinct peak.

The size of the peak is relative to the concentration of the analyte introduced to the instrument.

End Result Chromatogram

The signal from the PID forms a picture over time, increasing when analyte is detected and decreases when analyte has left the detection stage. The picture is formed over the time at which all the analytes are introduced into the column to the end of the analysis and that picture is called a chromatogram. Each of the peaks in the chromatogram corresponds to one of the analytes detected by the system. The time at which the peak crests is called the retention time and the size of the peak corresponds to the concentration.

Talk with our sales team today to find out how the FROG can help you make faster, data-based decisions in the field.

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