cytiva pH/C-902 Manual de instrucciones - Página 2

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WARNING

When using hazardous chemicals, always use

protective glasses and other suitable personal

protection equipment.

Installation

The instrument is delivered pre-installed in ÄKTAprocess system

with all electrical connections prepared inside the electronics

cabinet. The conductivity cells and the pH electrode flow cell holder

are also mounted in proper positions.

WARNING

The electronics cabinet of the ÄKTAprocess

system must only be opened by personnel

authorized by Cytiva.

Operation

When the system is powered, the instrument is simultaneously

switched on. The monitor can be used immediately, but the full

specifications are not reached until after a warm-up period of

15 minutes.

The pH/C-902 Monitor has no user interface for the operator. It is

controlled entirely via UNICORN control software (version 5.0 or

later). The pH and conductivity values, as well as the temperature, are

displayed in the System Control module of the UNICORN control

software.

Note: The measured temperature is the temperature in the

conductivity flow cell, which can differ from the ambient

temperature.

Preparing the instrument

The following settings and calibrations may be necessary to perform

as described below:

•

Set up conductivity temperature compensation

•

Calibrate the conductivity cells

•

Prepare and insert the pH electrode

•

Calibrate the pH electrode

•

Set up pH temperature compensation

Setting up the conductivity temperature compensation

The conductivity in a buffer is temperature dependent. Temperature

compensation should be used when relating conductivity to

concentration and/or comparing conductivity values. The

compensation consists of a compensation factor together with a

reference temperature. All conductivity values will then

automatically be converted to the set reference temperature.

In the UNICORN System Control module:

Step

Action

Select System:Settings.

Result: The Instructions dialog box opens.

Select Monitors and click Cond_CIR101 or Cond_CIR102.

Enter a temperature compensation value between 0 and

9.99% in the CompFactor box.

Click OK.

The factor is expressed in percentage increase of conductivity per ℃

increase in temperature. If the temperature compensation factor is

unknown, a general approximate value of 2% can be set for many

common salt buffers.

Check the OFF-box in the Instructions dialog box for no

temperature compensation.

Calibrating the conductivity cell

Normally it is not necessary to adjust the cell constant as the flow cell

is pre-calibrated on delivery. The conductivity flow cell constant is

shown on the packaging and can be entered when the cell is

changed. Adjustment is only necessary when replacing the

conductivity cell with a flow cell whose constant is unknown.

However, it is also recommended that the flow cell is recalibrated

after cleaning.

The cell constant is adjusted in the UNICORN System Control

module.

Setting the constant for a new conductivity cell

The following instruction is applicable for a conductivity cell where

the constant value is known:

Step

Action

Read the constant value from the packaging.

Selec System:Calibrate.

Result: The Calibration dialog box opens.

In the Monitor box, select CIT101_Cel or CIT102_Cel.

Type the constant value in the Reference Value 1 box.

Click the Read Value 1 button.

Result: The measured value is displayed in the Measured

value box.

Click the Close button to exit the dialog box.

Calibrating the conductivity cell

Note: The conductivity temperature compensation must not be

activated when the cell constant is adjusted. Set the

compensation to OFF in the Instructions dialog box.

Step

Action

Prepare a calibration solution of 1.00 M NaCl, 58.44 g/l. Let the

solution rest until it is at room temperature. This is important

for exact measurements.

Fill the flow cell completely with the calibration solution by

pumping at least 15 ml through the cell with a syringe.

pH/C-902 Instruction 14003958 AB