GC Emulation Mode

To use the F-900 to analyze a small sample in a syringe, the GC Emulation Mode should be used. With the simple addition of our inline injection port, small volumes of analyte can be accurately measured.

Calibration standard gas is not required for using GC Emulation Mode. Simultaneous results can be collected for all enabled sensors.

There are several improvements compared to a Gas Chromatograph (GC):

No need for N₂, H₂, or bottled air.
Portable.
No heating or oven required.
Predicts ethylene concentration without chromatography.

Figure 13: GC Emulation port connected to front of instrument for small volume samples.

How GC Emulation Mode Works

The GC Emulation Mode employs a patent pending Flow Inject Analysis to determine ethylene concentrations with minimum sample volume of 10ml (larger sample volumes, such as 50 ml, will provide greater accuracy). The resulting value is then compared against a user-definable calibration point and an estimated concentration is determined. As shown by Equation 1 below, the injection volume is determined by the expected concentration of ethylene and the detection limits of the sensor. If interfering gases are expected, their expected concentrations must be subtracted from the reported ethylene concentration.

Exceeding the lower limit of Equation 1 will decrease the accuracy and precision of the result. Exceeding the upper limit will affect the sensitivity of the instrument and will cause the instrument to under-estimate measurements for up to 24 hours. A new calibration point may be required.

Each injection should be done by the same technician, as human technique will alter the result.

GC Emulation Mode Tips

If the expected sample’s C₂H₄ concentration is > 2 ppm, use a higher flow rate to increase signal detection.
In general, higher injection volume will also increase signal detection (ex: 50 ml). Recommended minimum injection volume is 10 ml. Once injection volume is set, please make sure to maintain the same volume of injection throughout all measurements.
The F-900 requires about 10 minutes of warm-up time when using GC Emulation Mode

When using GC Emulation Mode, the protocol is to perform 1 injection per sample, which takes approximately 5 minutes:

Stabilization time
Sample injection (at least 10 mL)
Processing time

Note: Injection mode standard error (at two sigma) is ±10% of gas concentration.

GC Emulation Mode Operation Procedure

Turn on GC Emulation Mode in the Setup > Measure menu. Press Save to save changes and exit to the main menu.
Enter the main Measure menu, Setup injection port then press Enter
Wait for the instrument to stabilize.
Set parameter then press Enter.
Inject the gas sample, then press Enter.
Wait while the sample is processing (~140 seconds).
View the results, Enter to repeat for another sample or Stop to exit.