Ionode IJ pH V5.1 - Manual (Page 19)

Ionode IJ Instruction Manual 19
4.3.1. Helpful Hints
1) Use the same technique to measure
samples as was used for calibration. Be
consistent with stirring rates, times and
conditions.
2) Ideally, the buffers and samples should be
at the same temperature.
3) Calibrate the pH electrode regularly, e.g.
typically once an hour for accuracy to within
±0.01 pH, or once a day for accuracy to
within ±0.1pH.
4) Use fresh buffers for calibration. Avoid
contamination of the stock buffer solution.
Do not use buffers beyond the expiry date.
Note alkaline buffers (pH 9.18 and 10.01)
absorb carbon dioxide from the air and
become
inaccurate. The magnitude
depends on the exposure time.
5) Keep all connections dry.
6) Use a dedicated high impedance pH meter.
7) Immerse the electrode so that the reference
junction is below the surface (see Figure 6 ).
8) Do not use in solutions of fluoride ion at low
pH. This will etch the glass membrane.
9) Sulphide vapours can permeate the
electrode wick and contaminate the
reference element. Minimize contact in such
environments and change the sleeve
electrolyte frequently.
10) The IJ44 is suitable for use in TRIS buffers
because the sleeve electrolyte does not
contain silver ions. In some conventional
single junction electrodes, silver ions in the
potassium chloride electrolyte react with
TRIS and cause spurious potentials at the
contact zone.