Determination of color
We used
black HACH2800 spectrophotometer (picture 1) to determine colors of taken groundwater
samples. We analyzed samples of all groups (picture 2). The selected program in
spectrophotometer was program no. 120. The wavelength of that program was 455
nm.
First we
made a blank sample by filling a square sample cell with 10 mL of deionized
water. The blank sample was inserted into cell holder with the fill line facing
right. Then the ZERO-button was pressed.
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| Picture 1 - HACH2800 spectrophotometer |
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| Picture 2 - Analyzed samples |
After
zeroing the spectrophotometer with blank sample the square sample cells were
filled with every group’s sample water. We inserted one cell at the time into
cell holder. Then the READ-button was pressed and results were given. Results from both color and nitrate are shown in the table 1.
Results
were in Pt/Co color scale and the units varied from 3 to 437. The maximum color units were determined from groundwater samples which were taken after pumping. The minimum color units were determined from groundwater sample which was taken before pumping. Color of surface water samples varied from 23 to 79 units. It was impossible to determine the color of the sample no. 11. Turbidity of that sample was too high so the result was OVERRANGE.
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| Picture 3 - Color difference between groundwater and surface water samples |
Determination of nitrate
We used the
same spectrophotometer to determine nitrate as we used in color determination.
The program no. 353 was selected for this determination with wavelength of 400
nm.
We also
used the same samples in square sample cells as we did in the determination of
color. We did one sample at a time because every sample was used to zero the
program before analyzing and the determination included reaction time.
After
zeroing the program by sample, the content of one NitraVer 5 Nitrate Reagent Powder Pillow was added into sample. Piece
of parafilm was added tightly around the mouth of the sample cell. The cell was
shaken in upright position for one minute. The five-minute waiting time started
straight after the shaking. After the five-minute reaction time was expired,
the sample was inserted into cell holder and the result was given after
pressing the READ-button. Then all the above-mentioned instructions were
repeated for another samples one at a time.
Results varied between 0.1 and 0.2 mg/L. The concentration of nitrate was so low that the spectrophotometer couldn't even determine all the samples. Results from groundwater samples no. 10 and 12 were negative which is not possible, so we changed the results showing 0.0 mg/L in the table 1.
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| Table 1 - Result from both determination of color and nitrate |
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