Factor = tds conductivity – Thermo Fisher Scientific CyberScan CON 10/CON 100/CON 200 User Manual

Page 17

4.3.2

Procedure for TDS calibration (CyberScan CON 10/200 only)

Two methods are available for TDS calibration. The first method (Method 1) applies to both

CyberScan CON 10 and 200 meters. Method 1 relies on the availability of a table that shows

the TDS values of the TDS calibration buffer solution at various temperatures. The second

method (Method 2) relies on the availability of conductivity-to-TDS conversion factors at

standard temperature such as at 25

C. Method 2 applies only to CyberScan CON 200 meter.

The advantage of Method 1 is that it is simpler to perform than Method 2. However, one

should note that much of calibration buffer solutions do not reference the TDS values at

temperatures other than 25

C, and that without the use of proper conductivity-to-TDS

conversion factor, this calibration may not be as accurate over a wider range of measurement.

Also, in some cases, the meter may not accept the TDS value input into it giving an error

message because the calibration value exceeds the allowable slope adjustment limits of the

meter when using a default conductivity-to-TDS conversion factor such as 0.50.

Method 2 overcomes the shortcomings of Method 1 by ensuring the TDS measurement

accuracy over a broader range of TDS measurements around the calibration value. The meter

will virtually accept any TDS calibration input from virtually any commonly used TDS

calibration buffer solution. The only requirement is that the buffer solution indicates the TDS at

a standard temperature such as 25

NOTE: It is important to have knowledge of the conductivity-to-TDS conversion factor or the

factor can be calculated using the formula below:

Factor =

TDS

Conductivity

@ 25