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18
PHO
TOMETER
7. PHOTOMETER
7.1. PROPER USE OF DROPPER BOTTLE
1. Tap the dropper on the table several times and wipe the outside of the tip with
a cloth.
2. Always keep the dropper bottle in a vertical position while dosing the reagent.
7.2. GLASS VIAL & 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 glass vial a couple of times or for a specified time: hold the glass vial
in the vertical position. Turn the glass vial upside-down and wait for all of the
solution to flow to the cap end, then return the glass vial to the upright vertical
position and wait for all of the solution to flow to the glass vial bottom. This is
one inversion. The correct speed for this mixing technique is 10 to 15 complete
inversions in 30 seconds. This mixing technique is indicated with “invert to mix”
and the following icon:
(b) The mixing method is indicated with “shake vigorously“ using the following icon: