PASCO CI-6507A User Manual

Instruction Sheet
for the PASCO
Model CI-6507A

pH electrode

012-06832A

06/98
$1.00

pH Sensor

pH electrode amplifier

cable with DIN
connectors

Connect to a

ScienceWorkshop

interface box

soaker bottle with
buffer solution

Introduction

The PASCO CI-6507A pH Sensor (pH electrode and
amplifier) is designed to be used with PASCO
ScienceWorkshop computer interface systems (300,
500, 700, and 750).

The pH electrode connects to the amplifier box with a
BNC connector, and the amplifier plugs into the
interface box directly or via a connecting cable.

The pH electrode is a standard type, producing an
electrical potential difference depending on the
hydrogen ion concentration (potential of hydrogen) in
a solution. The pH electrode is stored in a small plastic
container that contains a pH 4 buffer solution.

The pH amplifier translates the potential differences
measured by the pH electrode into the voltages
required by the Science Workshop interface. The
amplifier allows any standard pH electrode to be used
with ScienceWorkshop.

Equipment

Included:

 PASCO CI-6507A pH amplifier
 pH electrode with soaker bottle
 connecting cable
 soaker bottle containing KCl buffer solution (pH 4)

Additional Equipment Required:

 ScienceWorkshop 300, 500, 700, or 750 Interface

Additional Material Required

 distilled water (for rinsing the pH electrode)
 buffer solutions, such as pH 4 and pH 7 (for

calibration of the electrode)

© 1998 PASCO scientific

pH Sensor 012-06832A

Using the pH Sensor

Calibrating the pH Sensor

Connecting the pH Sensor to the interface box

1. Connect the 8-pin DIN plug of the pH Sensor

amplifier box into analog channel A, B or C of
the computer interface (Figure 1a).
or
Use the supplied cable to connect the pH
electrode amplifier box to the analog channel of
the interface box (Figure 1b).

ab

ISE

Plug into analog
channel A, B, or C

to analog channel
on the computer
interface

Figure 1

Connecting the pH electrode amplifier to the computer
interface (two methods)

2. Unscrew and remove the protective soaker bottle

from the end of the pH electrode, leaving the O­ring and cap in place on the shaft of the pH
electrode.

3. Rinse the electrode tip in distilled water. If

bubbles are seen in the pH electrode bulb, gently
shake the electrode downward (similar to
shaking down a thermometer) until the bubbles
disappear.

4. Connect the pH electrode to the BNC connector

of the pH electrode amplifier (Figure 2). Insert
the plug at the end of the electrode cable over the
BNC connector, and twist the plug one quarter
turn clockwise to lock it onto the BNC
connector.

Two Buffer Method:

One Buffer Method:

➤ Note: Use buffer solutions that are at a

temperature similar to the temperature of the
sample to be measured.

1. Run the ScienceWorkshop program. In the

Experiment Setup window, set up the
ScienceWorkshop interface and sensor so the pH
Sensor is connected into the correct analog
channel of the interface.

2. In the Experiment Setup window, double-click

the pH Sensor icon to open the sensors setup
window. (Note: In ScienceWorkshop version 3,
click the Calibration tab located near the top of
the sensors setup window.

3. Place the pH electrode in a high pH buffer

solution and wait about 30 seconds for the
voltage readings to stabilize.

4. Once the readings have stabilized, click the Take
Reading button. Enter the pH value of the high
pH buffer solution in the High Value box.

5. Rinse the pH electrode with distilled water and
then place the pH electrode in a second solution,
such as a low pH buffer solution. Wait about 30
seconds for the voltage readings to stabilize.
Again, after the readings have stabilized, click
the Take Reading button. Enter the pH value of
the low pH buffer solution in the Low Value
box. Click OK to return to the Experiment Setup
window.

1. Choose a buffer of known pH that is close to the
pH of the unknown.

2. Place the electrode in the buffer solution and
wait about 30 seconds for the voltage readings
stabilize.

Figure 2

Connecting the pH electrode to the amplifier

3. Type the pH of the buffer solution in the High
Value box, and click Take Reading.

4. Type 0 in the Low Value box, and type 0 in the
Volts box next to the Low Value box.

2