19
PHO
TOMETER
7.3. CUVETTE PREPARATION
Proper mixing is very important for reproducibility of the measurements. The proper
mixing technique is listed in the method procedure.
(a) The mixing method is indicated with “shake gently“ using one of the following icons:
(b) The mixing method is indicated with “swirl“ using one of the following icons:
In order to avoid reagent leaking and to obtain more accurate
measurements, close the cuvette first with the supplied HDPE
plastic stopper
and then the black cap.
Whenever the cuvette is placed into the measurement holder,
it must be dry outside and free of fingerprints, oil or dirt. Wipe it
thoroughly with
HI731318
microfiber cleaning cloth or a lint-free
wipe prior to insertion.
Shaking the cuvette can generate bubbles in the sample,
causing higher readings. To obtain accurate measurements,
remove such bubbles by swirling or by gently tapping the
cuvette.
Do not let the reacted sample stand too long after reagent
has been added. For best accuracy, respect the timings
described in the method.
It is possible to take multiple readings in a row, but it is recommended to take a new
zero reading for each sample and to use the same cuvette for zeroing and measurement
when possible.
Discard the sample immediately after the reading has been taken, or the glass might
become permanently stained.
All the reaction times reported in this manual are at 25 °C (77 °F). In general, the
reaction time should be increased for temperatures lower than 20 °C (68 °F), and
decreased for temperatures higher than 25 °C (77 °F).