GAOTek PH Meter with 2 Points Calibration (Electrode Slope)

Additional Information

ACCESSORIES:

• pH Electrode
• Temperature Probe
• pH Buffer Solutions (pH4.01/7.00/10.01)
• 9V Battery

Display

The pH meter is equipped with a clear and bright LCD display that is used to show measured values, mode indicators and help message. The following table describes the meaning of each indicator.

Keypad

The meter has 6 multifunction keys, names and symbols describe function key controls.

KEY	FUNCTION
MEAS | HOLD	Freezes the measured value on the display, press the key again to resume measuring. In the calibration or setting mode, exits current mode and returns to measurement.
SETUP	Enters the Setup Menu.
°F, °C	Enters the temperature setting mode.
SAVE |	In the measurement mode, press the key to store current measured value. In the temperature setting mode, press  key once, the setting value will increase by 0.1. Press and hold key, the setting value will increase by 1. In the memory mode, press  key to search the previous stored data.
VIEW |	In the measurement mode, press the key to recall stored data in the memory. In the temperature setting mode, press  key once, the setting value will decrease by 0.1. Press and hold key, the setting value will decrease by 1. In the memory mode, press  key to search the next stored data.
ENTER	Toggles between pH and mV measurement modes. Press the key to confirm option or input values.

Inserting the Battery

The device is packaged with one 9V battery. Before using, insert the batteries into the battery compartment, follow the procedure outlined below.

1. Remove the battery compartment cover from the meter’s backside.

2. Insert the battery into the battery compartment, note polarity.

3. Replace the battery compartment cover to its original position. Installation is completed.

Connecting the pH Electrode

1. Take out the pH electrode from the carrying case.
2. Insert the connector of the electrode into the BNC connector socket on the meter. Rotate and push the connector clockwise until it locks. After connection is completed, do not pull on the sensor cord. Always make sure that the connector is clean and dry.

Preparing the pH Buffer Solutions

The pH meter is packaged with three pH buffer packets required for calibration.

• Open the pH7.00 buffer packet, place the powder into a 250 ml volumetric flask. Pour distilled water 250 ml to scale line, mix the solution until reagent is completely dissolved.
• Preparation of 01 and 10.01 standard buffer solutions are the same as above.
• Prepared standard buffer solutions should be stored in hermetically sealed glass

Prior to Use

• Remove the protective cap from the bottom of the pH electrode.
• If the glass sensitive membrane on the electrode dries out, soak the sensor in 3M KCL solution or tap water for at least 15 minutes. DO NOT use distilled or deionized water, it will shorten the life of sensor.

Power On/Off

1. Push the switch to “ON” position, the display shows measured value.
2. Push the switch to “OFF” position, turn off the meter.

The pH meter contains two temperature units. If necessary, follow the steps below to set the desired measurement unit.Selecting the Temperature Unit

1. Press SETUP key to enter the setup menu.
2. Press  or  key to select the “Temperature units” option.

3. Press ENTER key to confirm, the “°C” indicator begins flashing.
4. Press or   key to select desired temperature unit (°F, °C).

5. Press ENTER key to confirm. Setting is completed

Setting the Real-Time Clock

The meter has a real time clock that is used to time-stamp stored data. Follow the steps below to set the date and time during the first use.

1. Press SETUP key to enter the setup menu. Press  or  keys to select “Date and Time” option.
2. Press ENTER key to confirm, the date digit begin flashing (Format: mm-dd).

3. Press or keys to set the current date. Press ENTER key to confirm, the hour digit begin flashing (Format: hh-mm).
4. Press or keys to set the current time. Press ENTER key to confirm, the meter returns to measurement mode. Setting is completed.

Temperature Compensation

In order to get accurate measuring results, you need to enable the manual or automatic temperature compensation before measurement or calibration.

AUTOMATIC TEMPERATURE COMPENSATION:

Insert the connector of temperature probe into the meter’s phone jack.

The “ATC” indicator immediately shows on the display, the meter is now switched to automatic temperature compensation mode.

MANUAL TEMPERATURE COMPENSATION:

1. DO NOT connect the temperature probe to meter.
2. Press °C key to enter the manual temperature setting mode.
3. Press  or key to set the temperature value of sample.
4. Press ENTER key to confirm, the meter returns to measurement mode. Setting is completed.

pH Calibration

The instrument can perform 2 points calibration in the pH mode. First calibration point must use the pH7.00 buffer solution. If your sample belongs to acidic substances, second point use the pH4.00 buffer solution, alkaline substances use the pH10.01 buffer solution. The meter will automatically recognize and calibrate to above standard buffer values.

The meter must be calibrated prior to first use or new electrode replaced. To ensure accuracy, regular calibration is recommended. Do not reuse calibration solution after calibration, contaminants in solution will affect the calibration and eventually the accuracy of the measurement.

1. Rinse the pH electrode with distilled water.
2. Press SETUP key, the meter enters setup menu.
3. Press ENTER key, the display shows calibration indicator and “7.00”.

4. Dip the pH electrode into the pH7.00 standard buffer solution, the end of the sensor must be completely immersed into the calibration solution. Stir the electrode gently.
5. Press ENTER key to confirm. Wait for the measured value to stabilize, the reading will automatically flash 3 times. First calibration point is completed. The display shows “—” indicating that the meter waits for second point calibration.

6. Rinse the pH electrode with distilled water. Dip the electrode into the pH4.01 or 10.01 standard buffer solution. Stir the sensor gently.
7. Press ENTER key to confirm. Wait for the measured value to stabilize, the reading will flash 3 times. Second calibration point is completed. The meter automatically shows electrode slope and returns to measurement mode. Calibration is completed.

8. During the calibration process, if the meter shows “Err”, please check pH electrode and calibration solutions are fresh and uncontaminated.
9. If you want to exit from calibration mode, press MEAS key, the meter will immediately return to measurement mode.

pH Measurement

1. Press ENTER key until the display shows measurement unit “pH”.
2. Rinse the pH electrode with distilled water to remove any impurities adhering to the probe body.
3. Dip the electrode into the sample solution, stir the sensor gently to create a homogeneous sample.
4. Wait for the measured value to stabilize, record the reading on the display.

mV Measurement

1. Press ENTER key until the display shows measurement unit “mV”.
2. Rinse the electrode thoroughly with distilled water.
3. Dip the electrode into the sample solution, stir the sensor gently.
4. Wait for the measured value to stabilize, record the reading on the display.

Hold Function

The device has a data hold function that is used to freeze the measured value. During the measurement process, press HOLD key, “HOLD” indicator appears on the display. Press HOLD key again to release the measured reading, you can continue to take measurements.

Storing and Recalling Data from Memory

The pH meter allows up to 50 data sets to be stored and recalled.

MEMORY INPUT:

In the measurement mode, press SAVE key to input measured value into the memory, the “Memory” indicator appears on the display. If the memory is full, the first value stored will be erased to create space for the new value.

MEMORY RECALL:

1. Press VIEW key in the measurement mode, the display shows ID number, date and time of the stored data.

2. Press  key, the display shows the stored data.

3. After the browsing, press MEAS key, the meter returns to measurement mode.

Electrode Care and Maintenance

Since pH electrode is susceptible to dirt and contamination, clean as necessary depending on the extent and condition of use.

AFTER MEASURING:

Rinse the pH electrode in distilled water, store the electrode into the electrode storage solution.

CLEANING THE ELECTRODE:

1. Salt deposits: Soak the electrode in warm tap water to dissolve deposits, then thoroughly rinse with distilled water.
2. Oil or Grease film: Wash the electrode bulb gently in some detergents and water. If necessary, use the alcohol to clean the electrode bulb, then rinse with distilled water. Place the sensor in the electrode storage solution for 30 minutes.
3. Clogged reference junction: Heat a diluted KCl solution to 140 °F to 176 °F (60 °C to 80 °C). Place the sensing part of the electrode into the heated solution for about 10 minutes. Allow the electrode to cool in some unheated KCl solution.
4. Protein deposits: Prepare a 1% pepsin solution in 0.1 M of HCL. Place the electrode in the solution for 10 minutes. Rinse the sensor with distilled water.

REACTIVATING THE ELECTRODE:

If stored and cleaned properly, the electrode should be ready for immediate use. However, a dehydrated bulb may cause sluggish response. To rehydrate the bulb, immerse the electrode in a pH4.01 buffer solution for 10 to 30 minutes. If this fails, the electrode requires activation.

1. Soak the pH electrode in 0.1 M HCl for 5 minutes.
2. Remove and rinse with deionized water, then place in 0.1 M NaOH for 5 minutes.
3. Remove and rinse again, and soak in electrode storage solution for 30 minutes.

HOW TO PREPARE THE ELECTRODE STORAGE SOLUTION:

Dissolve 22.365 grams of potassium chloride reagent (KCL) in the 100 mL distilled water. Stir the solution until the solution has thoroughly mixed.

Optional pH Electrodes

The device is equipped with a general purpose pH electrode, if it cannot fully meet your measurement requirements, refer to the table below to select an applicable sensor.