EUTECH INSTRUMENTS CYBERCOMM 5000 FOR CYBERSCAN 5000 Manual de instrucciones descargar pdf (Pagina 168)

Instruction Manual CyberScan PC5500/ 5000

163

Analate Addition and Analate Subtraction

In the Analate methods, the initial millivolt reading is taken with the

electrode immersed in the standard; then an aliquot of sample is

added, and the final millivolt reading is taken. Sample concentration

is calculated from the change in the millivolt readings.

Analate Addition

s std

+ V

std

( )

E/S

std

( )

Analate Subtraction

s std

+ V

std

( )

E/S

std

( )

As with known addition, with analate addition the sample and the

standard solution contain the same ion being measured. With analate

subtraction, the ion being measured. With analate subtraction; the ion

being measured is in the standard solution, and not in the sample

solution. For example, a fluoride standard and a fluoride ISE might be

used to measure to aluminium concentration of a sample. When the

sample containing aluminium is added to the standard it reduces the

measured fluoride content of the standard. The amount of reduction

is proportional to the aluminium in the sample.

The analate methods offer the same advantages as do the addition

methods in that they effectively deal with complex samples. A distinct

advantage of the analate subtraction method is that it can be used in

cases where an ISE does not exist for a given species, such as

aluminium in the example cited.

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EUTECH INSTRUMENTS CYBERCOMM 5000 FOR CYBERSCAN 5000 Manual de instrucciones Pagina 168