Vernier Software and Technology
Vernier Software & Technology

Go Direct® Ion-Selective Electrode Amplifier User Manual

Go Direct® Ion-Selective Electrode Amplifier

Use our Go Direct ISE Amplifier to collect data from any Vernier ion-selective electrode (ISE). The Go Direct ISE Amplifier can produce an output in mV or mg/L when connected to an electrode. It can also work with third party electrodes.

Note: Vernier products are designed for educational use. Our products are not designed nor are they recommended for any industrial, medical, or commercial process such as life support, patient diagnosis, control of a manufacturing process, or industrial testing of any kind.

What's Included

  • Go Direct ISE Amplifier
  • Micro USB Cable

Compatible Software

Getting Started

Please see the following link for platform-specific connection information:

Bluetooth Connection

USB Connection

  1. Install Graphical Analysis 4 on your computer, Chromebook™, or mobile device. See for software availability.
  2. Charge your sensor for at least 2 hours before first use.
  3. Prepare a BNC ion-selective electrode (not included) by connecting it to the Go Direct ISE Amplifier and soaking it in the High Standard solution for 30 minutes. Refer to the electrode’s manual for more information.
  4. Turn on your sensor by pressing the power button once. The Bluetooth® LED will blink red.
  5. Launch Graphical Analysis 4.
  6. Click or tap Sensor Data Collection.
  7. Click or tap your Go Direct sensor from the list of Discovered Wireless Devices. Your sensor's ID is located near the barcode on the sensor. The Bluetooth LED will blink green when it is successfully connected.
  8. This is a multi-channel sensor. The active channel is listed in the Connected Devices Sensor Channels list. To change channels, select the check box next to the Sensor Channel(s) you would like to activate.
  9. Click or tap Done to enter data-collection mode.
  10. For best results, perform a two-point calibration using the High and Low Standard solutions. Refer to the electrode’s manual for more information.
  1. Prepare a BNC ion-selective electrode (not included) by connecting it to the Go Direct ISE Amplifier and soaking it in the High Standard solution for 30 minutes. Refer to the electrode’s manual for more information.
  2. Install Graphical Analysis 4 on your computer or Chromebook. If using LabQuest 2, make sure LabQuest App is up to date. See for software availability or to update LabQuest App.
  3. Connect the sensor to the USB port.
  4. Launch Graphical Analysis 4 or turn on LabQuest 2.
  5. This is a multi-channel sensor. To change the default channel selections, see
  6. For best results, perform a two-point calibration using the High and Low Standard solutions. Refer to the electrode’s manual for more information.

Charging the Sensor

Connect the Go Direct ISE Amplifier to the included USB micro cable and any USB device for two hours.

You can also charge up to eight Go Direct ISE Amplifiers using our Go Direct Charge Station, sold separately (order code: GDX-CRG).


Blue LED is on steady while sensor is connected to the Charging Cable or Charge Station.

Fully charged

Blue LED is off when charging is complete.

Powering the Sensor

Turning on the sensor

Press button once. Red LED indicator flashes when unit is on.

Putting the sensor in sleep mode

Press and hold button for more than three seconds to put into sleep mode. Red LED indicator stops flashing when sleeping.

Connecting the Sensor

See the following link for up-to-date connection information:

Connecting via Bluetooth

Ready to connect Red LED flashes when sensor is awake and ready to connect.
Connected Green LED flashes when sensor is connected via Bluetooth.

Connecting via USB

Connected and charging Blue and Green LEDs are solid when sensor is connected to Graphical Analysis via USB and unit is charging. (Green LED is obscured by the blue one.)
Connected, fully charged Green LED is solid when sensor is connected to Graphical Analysis via USB and the unit is fully charged.
Charging via USB,
connected via Bluetooth
Blue LED is solid and green LED is flashing, but the green flashing LED looks white because it is overwhelmed by the blue.

Using the Product


Go Direct ISE Amplifier has six measurement channels:

  • Potential (mV)
  • Chloride (mg/L)
  • Ammonium (mg/L)
  • Calcium (mg/L)
  • Nitrate (mg/L)
  • Potassium (mg/L)

Note: The Potential channel is the default channel for this sensor. All channels are mutually exclusive except Potential (i.e., You can display one concentration channel and Potential at the same time, but you cannot display two concentration channels at the same time). In order to collect data from the other concentration channels, you must also attach the applicable corresponding BNC electrode to the ISE.


If an ion-selective electrode is attached, a two-point calibration is recommended for the most accurate results. For additional calibration information, see

In order to calibrate an ISE electrode/ISE amplifier combination, or to confirm that a saved calibration is accurate, you should have a supply of ISE standard solutions that cover the range of the concentration values you will be measuring. For more information about ISE standard solutions, including recipes for preparation, see

Once you have calibrated a Go Direct sensor, the calibration is automatically stored to the sensor and will be used each time you connect to your device. You can always choose to restore factory defaults if you feel the custom calibration is invalid.

If you are measuring potential, calibration is not required. Calibration is disabled in this mode to ensure the best results. For additional calibration information, see



–1000 mV to +1000 mV


0.01 mV

USB specification


Wireless specification

Bluetooth 4.2

Maximum wireless range

30 m


8.5 cm × 3.5 cm × 1.75 cm


300 mA Li-Poly

Battery life (single full charge)

~24 hours

Battery life (long term)

~500 full charge cycles (several years depending on usage)

Care and Maintenance

Battery Information

Go Direct ISE Amplifier contains a small lithium-ion battery. The system is designed to consume very little power and not put heavy demands on the battery. Although the battery is warranted for one year, the expected battery life should be several years. Replacement batteries are available from Vernier (order code: GDX-BAT-300).

Storage and Maintenance

To store Go Direct ISE Amplifier for extended periods of time, put the device in sleep mode by holding the power button down for at least three seconds. The red LED will stop flashing to show that the unit is in sleep mode. Over several months, the battery will discharge but will not be damaged. After such storage, charge the device for a few hours, and the unit will be ready to go.

Exposing the battery to temperatures over 35°C (95°F) will reduce its lifespan. If possible, store the device in an area that is not exposed to temperature extremes.

Water Resistance

Go Direct ISE Amplifier is not water resistant and should never be immersed in water.

If water gets into the device, immediately power the unit down (press and hold the power button for more than three seconds). Disconnect the sensor and charging cable, and remove the battery. Allow the device to dry thoroughly before attempting to use the device again. Do not attempt to dry using an external heat source.

How the Sensor Works

Go Direct ISE Amplifier is a circuit that allows the voltage output of the electrode to be monitored. Firmware on the amplifier automatically uses the Nernst equation to convert the Potential reading to Concentration when the appropriate sensor channel is connected. The electrode is connected to the BNC connector on one end of the amplifier. Go Direct ISE Amplifier will initially default to report values in units of mV.


For troubleshooting and FAQs, see

Repair Information

If you have followed the troubleshooting steps and are still having trouble with your Go Direct ISE Amplifier, contact Vernier Technical Support at or call 888-837-6437. Support specialists will work with you to determine if the unit needs to be sent in for repair. At that time, a Return Merchandise Authorization (RMA) number will be issued and instructions will be communicated on how to return the unit for repair.



Vernier warrants this product to be free from defects in materials and workmanship for a period of five years from the date of shipment to the customer. This warranty does not cover damage to the product caused by abuse or improper use. This warranty covers educational institutions only.


When disposing of this electronic product, do not treat it as household waste. Its disposal is subject to regulations that vary by country and region. This item should be given to an applicable collection point for the recycling of electrical and electronic equipment. By ensuring that this product is disposed of correctly, you help prevent potential negative consequences on human health or on the environment. The recycling of materials will help to conserve natural resources. For more detailed information about recycling this product, contact your local city office or your disposal service.

Battery recycling information is available at

Do not puncture or expose the battery to excessive heat or flame.

The symbol, shown here, indicates that this product must not be disposed of in a standard waste container.

Contact Support

Fill out our online support form or call us toll-free at 1-888-837-6437.

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