13
3.4 Single-Vial Procedure
1. Place the sample vial filled with the water sample in the SP-800 sample vial compartment and press
the ZERO button. The SP-800will display the page shown in Figure 7.
2. Take the sample vial out and add the reagent to the sample vial.
3. Place sample vial back into the sample vial compartment and press the timer button TMR1. The
SP-800 will start to monitor the reaction between the reagent and the species you want to measure
in the water sample. The concentration is shown in the chart as a function of time (Figure 8).
4. When the timer reaches the preset time and the reaction is complete, the value of concentration
will be shown on the top right corner of the page.
5. The rate of the reaction is often faster than the standard pre-set time, which will become apparent
from the concentration-time plot. You can press the STOP button to stop the timer and terminate
the timing step. The last read concentration value will be displayed on the top right corner of the
page after you terminate the timing step.
Figure 7. Concentration as a Function of Time
3.5 Two-Vial Methods
Some colorimetric methods require using two vials. The water sample is added to two identical vials. One
vial is being used to zero the colorimeter, referred as to the prepared blank. A reagent is added to the other
vial, referred as to the prepared sample. The absorbance value is determined from the prepared sample.
If the method requires two or more reagents, the prepared blank could be the resulting solution after one
or more reagents have been added to the sample.
The following procedure is typical for two-vial methods:
1. Place the prepared blank into the SP-800 sample vial compartment and press the ZERO button to
zero the instrument.
2. Place the prepared sample into the SP-800 sample vial compartment and press the TMR1 button
to start the method timer.
3. When the timing step is completed, the measured concentration will be displayed on the top of the
page. The timing step could be terminated earlier by pressing STOP button.
4. Optionally, the SP-800 can be re-zeroed using the prepared blank after the timing step is completed
or terminated. The blank reading will be subtracted from the measured concentration value, and
the displayed concentration value on the top-right corner will be updated. This step is optional. It is
only necessary if the prepared blank changes its color during the timing period.
5. Optionally, the prepared sample vial can be put back and read again by pressing the READ button
if the blank is re-zeroed after the timing step is completed or terminated. A new concentration value
based on the last absorbance value measured will be calculated and displayed.
To Next Page
Loading...
