Go Direct® Mini GC™ (GDX-GC)

Specifications and User Guide

Troubleshooting

General: Press the power button on the sensor to turn it on. Connect your sensor as described in the Getting Started instructions for your device.

COMMON ISSUES

  • Inconsistent Flow
    ⚬ Likely Cause: Worn or damaged septum.
    ⚬ Solution: Replace the septum.
  • Inconsistent Peak Areas
    ⚬ Likely Cause: Irregular injection volume or worn septum.
    ⚬ Solution: Check your injection technique and replace the septum.
  • No Communication
    ⚬ Likely Cause: Software mismatch or cable/Bluetooth connection.
    ⚬ Solution: Be sure you’re using Instrumental Analysis software. Check USB cables or verify Bluetooth pairing.
  • No Power
    ⚬ Likely Cause: Power cord or switch issue.
    ⚬ Solution: Confirm that power plugs are fully inserted and the switch is turned on.

General Use Tips

  • Use Approved Compounds Only: Always refer to the list of acceptable compounds in the user guide before injecting new samples.
  • Avoid High-Water Samples: Do not inject samples that contain more than 5% water. Water can damage the detector.
  • Hamilton Syringe Note: The syringe shipped with the device has a brown bumper on the needle. Do not remove this bumper—it protects the injection port.

Also see Best Practice Techniques for Vernier gas chromatographs

Top Questions

The Go Direct Mini GC uses a chemiresistive carbon nanotube (CNT) detector. This is different from the MEMS (thermal conductivity) detectors used in older models. The CNT detector offers high sensitivity to both polar and nonpolar organic compounds.

See also How is the Go Direct Mini GC different than previous versions of the Mini GC?

Because the CNT detector measures resistance change rather than voltage output, the signal is displayed as “Normalized Response”, not millivolts. This allows for comparison of peak shapes and retention times, but it is not intended for quantifying absolute concentration values without calibration.

No. The output from the CNT detector does not translate directly to millivolts, so the system does not support mV display like the older Mini GC Plus.

Baseline drift is expected with chemiresistive detectors, but here are some tips to manage it:

  • Pay attention to the Y-Axis scale: If your sample has a low signal, even small baseline drift will appear more significant. Try increasing the injection volume or adjusting your temperature and pressure settings to improve peak size.
  • Use an isothermal temperature profile: If you’re analyzing a single compound, there’s no need for a temperature ramp. A constant temperature minimizes drift. Only use a ramp when separating complex mixtures.
  • Subtract the baseline: If your signal contains consistent electronic noise or drift, using the baseline subtraction feature in the software can improve the clarity and accuracy of your chromatogram.
  • Review the temperature and pressure settings. These may need to be optimized for the Go Direct unit (they differ from Mini GC Plus settings).
  • Start with our published experiments and example profiles in the Go Direct Mini GC Compound Library
  • Use injection volumes between 0.1–0.3 μL and ensure consistent injection technique.
  • Replace the septum regularly if you’re seeing split peaks or tailing.

All samples—liquid or gas—must be injected using a syringe through the septum. For more information, see Can I inject a gas into the Vernier gas chromatographs?

  • Septum: Replace regularly (every ~40–50 injections).
  • Column: Run a high-temp clean cycle with a volatile like acetone to remove residue.
  • Power: Use a short USB cable or a powered USB hub if you’re experiencing communication issues.

Note: For column and/or sensor replacement, email chemistry@vernier.com for assistance.

The Go Direct Mini GC uses Instrumental Analysis, our free software compatible with Windows, macOS, iOS, iPadOS, Android, and Chrome. The sensor can also be used with the LabQuest App (LabQuest 2 or LabQuest 3 only). It is not supported in Logger Pro.

No. Logger Pro is not compatible with the Go Direct Mini GC. Use Instrumental Analysis, LabQuest 2, or LabQuest 3 instead.

This could indicate a clogged column or septum leak. Try:

  • Replacing the septum.
  • Running a cleaning cycle with acetone at high temperature.
  • Checking the power connection and USB cable.

Yes, but the column and detector are different, so this may cause confusion. Review our guide:
How is the Go Direct Mini GC different than previous versions of the Mini GC?

Additional Troubleshooting

Specifications

  • Column: Restek MXT-502.2 Column
    ⚬ Siltek-treated stainless steel with proprietary diphenyl/dimethyl polysiloxane phase
  • Column operating temperature: 30°C to 160°C
    ⚬ maximum heating ramp: 10°C/min
  • Detector: Seacoast Science carbon-nanotube chemiresistive detector
  • Carrier gas: Ambient air
  • Operating pressure: 1 to 21 kPa (above ambient pressure)
  • Environmental conditions
    ⚬ Temperature: 5°C to 40°C
    ⚬ Humidity: 95% or less (non-condensing environment)
  • Liquid injection volume: 0.01 to 0.6 µL
  • Dimensions: 108 mm height, 191 mm length, 133 mm width
    ⚬ Weight: 1.3 kg
  • Power Requirements: 24 VDC, 2.5 A from an external power supply
  • Utility: External power supply rated for 100–240 VAC, 1.5 A 50–60 Hz
  • Connections:
    ⚬ Wireless: Bluetooth® v4.2 (wireless range 30 m unobstructed)
    ⚬ Wired: USB 2.0 full speed

Related Products

Replacement Parts

For column and/or sensor replacement, email chemistry@vernier.com for assistance.

Published: April 28, 2020. Updated: August 8, 2025.