Hanna-instruments HI 93414 Manual do Utilizador descarregar pdf (Página 20)

HEATING THE SAMPLE

Use of heat to remove air bubbles, although very effective in some cases, should be handled with care

because it can alter the turbidity of the sample. When heating a sample, the volatile components

from the sample can vaporize, the suspended components can dissolve or the sample characteristics

can change.

Therefore, the heating procedure should be used with extreme care.

The best way is to use a warm water bath and immerse the cuvette with sample into the bath. Heat

the sample only until the visible bubbles are removed.

Note: Always cool the heated sample to the original sample temperature before measurement.

The heating procedure can be used in combination with vacuum or ultrasonic waves application for

a more effective air bubble removal.

REAGENT ADDING (COLORIMETRY only)

• Because the reagent quantity is set up to react with 10 mL of

sample is very important to fill the cuvette correctly. The liquid in

the cuvette forms a convexity on the top; the bottom of this convexity

must be at the same level with the 10 mL mark.

• To open the powder reagent pack:

a) use scissors to open the powder packet

b) push the edges of the packet to form a spout

c) pour the content of the packet

• Do not let the reacted sample to stand too long after reagent is added or accuracy will be lost.

• All the reaction times reported in this manual are reffered to 20 ºC (68 ºF). As a general rule of

thumb, they should be doubled at 10 ºC (50 ºF) and halved at 30 ºC (86 ºF).

• Insert the cuvette with the mark aligned with the mark on the instrument top.

• 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.

• After the reading it is important to discard immediately the sample, otherwise the glass might

become permanently stained.

Note:In order to maximize accuracy, prior to a measurement follow the validation procedure, to

be sure that the instrument is properly calibrated. If necessary, calibrate the instrument.

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Hanna-instruments HI 93414 Manual do Utilizador Página 20