18
PHO
TOMETER
7. PHOTOMETER
7.1. PROPER USE OF POWDER PACKET
1. Use scissors to open the powder packet.
2. Push the edges of the packet to form a spout.
3. Pour out the content of the packet.
7.2. CUVETTE PREPARATION
Proper mixing is very important for reproducibility of the measurements. The proper
mixing technique is listed in the method procedure.
Invert the cuvette a couple of times or for a specified time: hold the cuvette in the
vertical position. Turn the cuvette upside-down and wait for all of the solution to flow
to the cap end, then return the cuvette to the upright vertical position and wait for all
of the solution to flow to the cuvette bottom. This is one inversion. The correct speed
for this mixing technique is 10-15 complete inversions in 30 seconds. This mixing
technique is indicated with “invert to mix” and 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.