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USING LIQUID AND POWDER REAGENTS
• Proper use of the dropper:
(a) for reproducible results, tap the dropper on the table for several times and wipe the outside of the
dropper tip with a cloth.
(b) always keep the dropper bottle in a vertical position while dosing the reagent.
• Proper use of the powder reagent packet:
(a) use scissors to open the powder packet;
(b) push the edges of the packet to form a spout;
(c) pour out the content of the packet.
USING CUVETTES
• Proper mixing of the cuvette is done by
shaking the cuvette
, moving the cuvette up and down. The
movement may be gentle or vigorous. This mixing method is indicated with “shake gently” or “shake
vigorously”, and one of the following icons:
(a)
(b)
The instructions listed below should be carefully followed during testing to ensure most accurate results.
• Color or suspended matter in large amounts may cause interference, they should be removed by
treatment with active carbon and filtration.
• Ensure the cuvette is filled correctly: the liquid in the cuvette forms a convexity on the top; the bottom
of this convexity must be at the same level of the 10 mL mark.
COLLECTING AND MEASURING SAMPLES
• In order to measure exactly 0.5 mL of reagent with the 1 mL syringe:
(a) push the plunger completely into the syringe and insert the tip into the solution.
(b) pull the plunger up until the lower edge of the seal is exactly on the 0.0 mL mark.
(c) take out the syringe and clean the outside of the syringe tip. Be sure that no drops are hanging
on the tip of the syringe, if so eliminate them. Then, keeping the syringe in vertical position above
the cuvette, push the plunger down into the syringe until the lower edge of the seal is exactly on
the 0.5 mL mark. Now the exact amount of 0.5 mL has been added to the cuvette, even if the
tip still contains some solution.
TIPS FOR AN ACCURATE MEASUREMENT
(c)
(a)
(b)
(c)
(a)
(b)
shake gently
shake vigorously
