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28.
ION: ANALATE ADDITION METHOD
The analyte addition method is useful when your sample is at an elevated temperature and you want to
negate the effect that temperature will have on the concentration calculation. This method is also useful if
you have only a small amount of sample available. The analyte addition method differs only slightly from
the known addition method. The difference being the solution that you are taking your initial mV reading in
is actually the standard and not the sample of interest. The difference in mV reading of the standard
before and after the sample is added is used to calculate the concentration of the ion of interest. With the
analyte addition method, both the sample and the standard solution contain the ionic species of interest.
You must use a minimum of two standards to standardize the meter.
1. Immerse the ion selective electrode in a known volume of the sample solution and stir gently.
2. Wait for the reading to stabilize. Touch "AA" to accept the current reading as first mV reading.
3. Add a known volume of standard solution to the sample.
4. Wait for the reading to stabilize. Touch "AA" to accept the current reading as second mV reading.
5. Use the keypad to enter the sample volume.
6. Select "Enter" to accept the value.
7. Use the keypad to enter the standard volume.
8. Select "Enter" to accept the value.
9. Use the keypad to enter the volume of the ISA solution added.
10. Select "Enter" to accept the value.
11. Use the keypad to enter the concentration of the standard solution.
12. Select "Enter" to accept the value.
13. The Analyte Addition result is now displayed. Select "Print" to send
the data to Printer if sample ID# has been assigned, or Select "OK"
to return to the Measure screen for a new measurement.
When using the Known Addition/Subtraction or Analyte Addition/
Subtraction, the current mV value will be shown as measured value
instead of "----".
37
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