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ADC LabNET offers direct detector connecting with extremely wide
dynamic range up to 107

Flame Ionisation Detector (FID)

Wide range of chromatographs have its own built-in electrometers but does not have its own ADC for digitising chromatographic signal. Most of the electrometers have analogue output in range (0-1mv, 0-1V,0-10V), and ADC converter is connected to this output.

Typically scheme of measurement on these instrument is built of electrometer plus connected at its output ADC. This way introduces several paths for noise intervention in measuring data.
  1. Noise intervention between detector and electrometer. It is typically depends on cable length, leads quality, cable quality.
  2. Noise impact at output of electrometer amplifier. It is typically depends on electrometer design and output voltage levels.
Figure 1. Typical scheme of measurement from FID detector.
FID low current cable up to 1 m Electrometer Low voltage cable 2-3m ADC Digital data to PC PC
     

ADC LabNET box connected to FIDSince we have deals with lots of chromatographs, we decided make our own approach in low current measurement from FID, NPD, ECD detectors.

ADC LabNET box shown at the left is a composition of electrometer and ADC. All in one. LabNET design allows place it in nearest possible to detector location, even at the top of chromatograph.

 
 

Figure 2. Signal path scheme in ADC LabNET directly connected to FID
FID low current cable 10 cm -1 m
(3 in - 3 ft)		 ADC LabNET module Digital data to PC PC
Electrometer ADC CPU
   

Besides of mentioned benefits and decreasing noise impact in data collecting path, we have built into ADC+Electrometer another feature: Automatic Gain Switching. This feature provided by built-in microcontroller allow signal registration in very high dynamic range e.g. it is possible to see on chromatogram main compound (solvent) - 99,99% of mixture and all impurities to the level of 0,00001%. Since AGS is working transparently for operator, there is no need in manual attenuation, signal zeroing etc. This approach gives new grade of metrological characteristics to instruments like Shimadzu-GC-17A, Tsvet-100, Tsvet-500 etc.