Ph Standardization; Ph Measurement - Fisher Scientific accumet AP 110 accumet AP 115 accumet AP 125 Instruction Manual

5.2 pH Standardization

For best results, standardizing (calibrating) your meter/
electrode system against certified accurate solutions is
strongly recommended due to electrode variations and
changes in electrode response over time. Daily
standardization with fresh buffers is common.
1. Press mode until the display indicates the pH
mode.
2. Immerse the rinsed electrode(s) into a buffer from
the chosen group (USA, NIST or EURO). Stir
moderately if possible. Buffers can be used in any
order, however neutral (pH 7) is ideally first.
3. Press std/enter to access the Standardize screen.
'Std' is now displayed indicating this mode.
4. Allow the pH value to reach a constant reading
(little variation over 30 seconds as well as the
appearance of the STABLE annunciator). Press
std/enter again to complete standardization of the
value.
buffer and returns to the Measure mode.
Successfully standardized buffer values remain on
the display until cleared—even after power off.
5. Repeat steps (2) to (4) with subsequent buffers.
The meter will briefly display 'EFF%' (efficiency as
% slope) before returning to the Measure mode.
If this value is not between 70-120%, 'SLOPE
Error' (Electrode error) is displayed. The
standardization value is not accepted and the
instrument returns to the Measure mode.

5.3 pH Measurement

1. Press mode until the display indicates the pH
mode. Immerse the electrode(s) into the sample
solution. Stir moderately if possible.
2. Allow the pH value to reach a constant reading
(little variation over 30 seconds as well as the
The meter automatically recognizes the
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