YSI pHotoFlex Series - Manual (Page 10)

Practical part pHotoFlex
®
Series
10 ba76126e01 03/2013
1.4 Working with the analysis timer
Many determination procedures include steps that need certain periods
of time to expire. All these periods are stored in the photometer. If the
analysis timer is switched on, a corresponding timer is activated for
each time-critical step according to the proceeding described in the
analysis specification. Only after all timers have expired can the photo-
metric measurement be started.
1.5 Sample dilution
Diluting the sample can be required for the following reasons:
 The expected concentration of the substance to be determined is
near or above the upper measuring range limit
 Other substances in the sample cause the measured values to be
too high or too low due to matrix interferences
With the pHotoFlex
®
Series you can measure diluted samples without
having to multiply the measured value by the dilution factor afterwards.
The measuring range is extended automatically. To do so, enter the di-
lution number in the photometer before measuring. Admissible are di-
lution numbers from 1+1 up to 1+99 (volume parts water + volume parts
test sample) in whole number steps.
For diluting, use deionized water and common laboratory dosing equip-
ment with sufficient dosing accuracy (volumetric flasks, pipettes etc.).
Note
Note that the dilution error can increase with an increasing dilution.
Therefore, check whether a different test or method with a suitable
measuring range can be used instead of diluting the sample.