Apera Instruments SX823-B User Manual

8
4.2 pH Calibration Consideration
4.2.1. Standard buffer solution
The meter uses two series of standard buffer solution: USA series and NIST series, 3 solutions for each
series which are corresponding to calibration indication icons. Please see Chart - 3 for the two series of
standard buffer solution.
Chart - 3 pH standard buffer solution series
Icons
pH standard buffer solution series
USA series
NIST series
Three-point calibration
4.00 pH
4.01 pH
7.00 pH
6.86 pH
10.01 pH
9.18 pH
4.2.2. Three-point calibration
The instrument can perform 1-3 points calibration. The first point calibration must use 7.00 pH (or 6.86 pH)
standard solution, then select other standard solution to perform the second and the third point calibration.
See chart - 4.
Chart - 4 Three-point calibration mode
USA standard
NIST standard
Icons
Suited range
One-point calibration
7.00 pH
6.86 pH
Accuracy
≥ ±0.1pH
Two-point calibration
7.00 pH → 4.00 pH
6.86 pH → 4.01 pH
Range< 7.00pH
7.00 pH → 10.01 pH
6.86 pH → 9.18 pH
Range> 7.00pH
Three-point calibration
7.00→4.00→10.01 pH
6.86→4.01→ 9.18 pH
Large Range
4.2.3. Calibration intervals
Calibration intervals depend on the sample, the electrode performance, and the required accuracy. For
high accuracy measurements (≤ ±0.03pH), the meter should be calibrated immediately before taking a
measurement. For general accuracy (≥±0.1pH), the meter can be calibrated and used for approximately
one week before the next calibration.
The meter must be recalibrated in the following situations:
(a) New probe or probe that has not been used for a long time
(b) After measuring acid (pH<2) or alkaline solutions (pH>12)
(c) After measuring a solution that contains fluoride or a concentrated organic solution
(d) If the solution’s temperature differs greatly from the calibration solution temperature

Apera Instruments SX823-B Specifications

General

Brand	Apera Instruments
Model	SX823-B
Category	Measuring Instruments
Language	English