Measuring Hints; Sample Measurements - Radiometer Analytical ISE25Pb Mode D'emploi

2+
For direct Pb measurements the sample pH should not exceed
the pH range 3-7. If the ionic strength cannot be adjusted properly,
or the sample contains an extremely high background concentra-
tion of other ions, methods other than direct measurements must
be applied, e.g. the standard addition or standard subtraction
methods.

Measuring Hints

For precise measurements, all samples and standards should
have the same temperature, preferably ambient temperature. The
electrode should not be used above 50°C.
Always rinse the electrode with distilled water between measure-
ments. Careful rinsing is important when the ISE25Pb has been
exposed to a rather concentrated solution and afterwards has to be
used in a very dilute solution. Effective rinsing is achieved by
flushing the electrode for about 15 secs. in two lots of distilled
water. Dab dry with a clean, soft tissue to prevent cross-contami-
nation.

Sample Measurements

If an ion meter is used e.g. PHM250 Ion Analyzer, the lead con-
centration can be read directly. If the potential is read, the lead
concentration corresponding to the measured potential must be
found from a calibration curve.
4