Xylem YSI VARiON Plus 700 IQ H, Operating Manual, Page: 32 / 62

Matrix adjustment, check and calibration VARiON
® Plus
700 IQ H
32
ba76207e02 12/2020
4.2.4 Special functions
The simple matrix adjustment, as described in the sections 4.2.2 to
4.2.3, will in most cases lead to precise measurement results. In some
cases, special effects in the matrix can cause the real characteristic
curve of the ISE measurement to deviate from the factory characteristic
curve. This can lead to measured values that are not precise enough.
After consultation with the service department, it is possible to provide
special functions to adjust the sensor for use in a special sample matrix
or special measurement conditions.
These special functions can be selected like the other procedures.
4.3 Check and calibration in standard solutions
4.3.1 General information on checking and calibrating
In addition to the comparison measurement or matrix adjustment under
real measurement conditions, it is possible to check the function of the
entire sensor in standard solutions. If necessary, you can also take
over in the sensor the slope and potential level of the individual elec-
trodes via an exact calibration in standard solutions. The slope will be
retained with a future matrix adjustment if it is carried out without
zeroing the electrode.
When does a check or
calibration make sense?
A check or calibration can be useful in the following special cases:
 If the measured values do not appear to be correct even after a care-
ful matrix adjustment and if you suspect the electrode slopes to have
changed
 If a new application is to be started whose sample composition con-
siderably deviates from that of the recommended application (see
section 1.3 R
ECOMMENDED FIELDS OF APPLICATION
)
 Routinely within the framework of the company quality assurance
The long term stable VARiON
®Plus
electrodes are calibra-
tion-free in the recommended application. A check in stan-
dard solutions is only of significance if all basic conditions
(cleanness, conditioning etc.) are strictly kept.
Calibrating the sensor is neither necessary nor recom-
mended.
Calibration can cause major measurement errors if the
basic conditions are not sufficiently kept. After calibrating,
a matrix adjustment in the sample is required in addition.
Standard solutions do not correspond to any real test
sample!