Ion: Analate Subtraction Method - Fisher Scientific accumet XL150 accumet XL200 accumet XL250 accumet XL500 accumet XL600 Reference Manual

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ION: ANALATE SUBTRACTION METHOD

The analyte subtraction method is useful when no ion specific electrode is available to measure the ion of
interest directly. Similar to the Known Subtraction method, the sample and the standard contain different
ionic species. However, the ion being measured is in the standard and not in the sample. The reduction of
free ions in the standard solution is proportional to the concentration of the ion of interest in the sample.
1. Immerse the ion selective electrode in a known volume of the standard solution and stir gently.
2. Wait for the reading to stabilize. Touch "AS" to accept the first mV reading of sample.
3. Add a known volume of sample solution to the standard.
4. Wait for the reading to stabilize. Touch "AS" to accept the second mV reading of sample.
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 Subtraction 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 "----".
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