Using a meter with millivolt readout only
1. Adjust the meter to measure mV.
2. Measure 50 mL of the more dilute standard with 50 mL of
TISAB II or with 5 mL of TISAB III into a 150 mL beaker.
Stir thoroughly.
3. Rinse electrode(s) with deionized water, blot dry and place
into the beaker. When a stable reading is displayed, record
the mV value and corresponding standard concentration,
4. Measure 50 mL of the more concentrated standard with
50 mL of TISAB II or with 5 mL of TISAB III into a 150 mL
beaker. Stir thoroughly.
5. Rinse electrode(s) with deionized water, blot dry and
place into the second beaker. When a stable reading is
displayed, record the mV value and corresponding
standard concentration.
6. Using a semilogarithmic graph paper, prepare a calibration
curve by plotting the mV values on the linear axis, and the
standard concentration values on the logarithmic axis.
See
Figure 1
.
7. Measure 50 mL of sample with 50 mL of TISAB II or with
5 mL of TISAB III into a 150 mL beaker. Stir thoroughly.
8. Rinse electrodes with deionized water, blot dry, and place
into the beaker. When a stable reading is displayed, record
the mV value.
9. Using the calibration curve prepared from step 6, determine
the unknown concentration.
13
Summary of Contents for 96-09
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