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. CYLINDER & CUVETTE PREPARATION
Proper mixing is very important for reproducibility of the measurements. The proper
mixing technique is listed in the method procedure.
(a) 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:
(b) The mixing method is indicated with “shake vigorously“ using one of the
following icons:
