Laboratory works

After field works we went to laboratory to analyze water samples

Ammonium nitrogen analysis

In this task we analyzed our group's and group 5's water samples. First we took water from samples  of the inflow and outflow of Pieni-Valkeinen, inflow of Iso-Valkeinen and groundwater from groundwater well and deionized water as zero sample in cuvettes. Then we pipetted 3 drops of Mineral Stabilizer and Polyvinyl Alcohol Dispersing Agent, and 1 ml of Nessler Reagent in each cuvette. We mixed cuvettes after every reagent. Then we waited 1 minute, and used Hach 2800 spectrophotometer to analyze amount of ammonium nitrogen. Before analyzing samples we reseted spectrophotometer with zero sample.

There are our results:
Group 5
1. 0,23 mg/l NH3-N
2. 0,24 mg/l NH3-N
3. 0,26 mg/l NH3-N
7. 0,07 mg/l NH3-N (groundwater sample)

Group 7
4. 0,20 mg/l NH3-N
5. 0,25 mg/l NH3-N    
6. 0,30 mg/l NH3-N
8. 0,57 mg/l NH3-N (groundwater sample)

Results are pretty similar except groundwater samples, our sample was muddy and other groups sample was almost clear.

LCK 349 Phosphate

Today our task was to measure the amount of phospate in our water samples.

So what we did step by step:

So after all this our results were as followed (amount of phosphate):

sample1: 0.012 mg/l 

sample2: 0.023 mg/l

sample3: 0.011 mg/l

sample4: 0.008 mg/l

sample5: 0.028 mg/l

sample6: 0.014 mg/l

sample7: 0.028 mg/l

sample8: 0.177 mg/l 

Water quality - Determination of suspended solids - Method by filtration through glass fibre filters

Principle:

Using a vacuum or pressure filtration apparatus the sample is filtered though a glass fibre filter. The filter is then dried at 105 C and the mass of the residue retained on the filter is determined by weighing.

We started this work by pouring our sample waters from one bottle to another, and between these two bottles we had fibre filter that catched suspended solids. The ammount of water we poured were 250 - 300 ml.

After this we placed the fibre filters to the oven where they were about 30-45mins.

Now we were able weigh in the filters, and compare their weight to the weight before the contamination.

This weight difference between the clear filter and dirty filter told us the amount of suspended solids in the filter.

Results:

Sample1          25.7 mg/l

Sample2          37.3 mg/l

Sample3          11.5 mg/l

Sample4          45.2 mg/l

Sample5          19.3 mg/l

Sample6          8.1   mg/l

Determination of chemical oxygen demand in water (COD Mn or KOMN4-number)

1. Take 18 flasks, number 0-8, each number two identical samples, sample 0 is deionized water each 10ml, 1-8 is 8 samples each 5ml sample and 5ml deionized water

2. Add 0.5 ml of H2SO4 (4M) and 2 ml of potassium permanganate to each of the 18 samples.

3. The flask is covered with foil paper (to avoid evaporating a large amount of sample by heating). After heating in boiling water for 20 minutes (group 0 is still purple, group 1-8 turns orange) and cools to room temperature in cold water.

4. Add 1ml of iodinated (yellowing) to the cooled sample.

And 5 drops of potassium iodide (blue)

Add the magnet to the magnetic stirrer and titrate the sample with sodium thiosulfate until the blue color disappears

Group	Sodium  thiosulfate
0	2.05	2.05
1	1.46	1.47
2	1.49	1.48
3	1.59	1.58
4	1.60	1.59
5	1.49	1.50
6	1.53	1.48
7	1.92	1.98
8	1.87	1.85

In this test, it was very interesting to see the different color change process of the entire sample, especially after the titration of sodium thiosulfate, the solution completely turned white like water.  We found that the clearer the sample, the less sodium thiosulfate used in the titration.  The instruments used in the experiment are volumetric flasks, titrators, automatic pipettes, etc. These instruments are very convenient for us to use, and make the experiment faster and more efficient.

Color, nitrate type and opacity determinations

The analyze of the color

We analyzed our group´s and fifth groups water samples. Firstly, we start by determining the color of the samples. We used for that the HACH 2800 spectrophotometer, the program number 120.  We pipetted 10 ml of ionized water to one cuvette, which we used for resetting. Then we pipped the water samples to eight cuves and measured the colors of the samples. 

 

 water samples and ionized water (0)

We had to analyze the color twice as at first try we placed the cuvettes by the wrong way in the spectrophotometer. We got a good remind that the line needs to be on the right side.

Results of the colors

Group 5

1.      47 PtCo

2.      39 PtCo

3.      34 PtCo

7. 7 PtCo

Group 7

4.      38 PtCo                                                                           

5.      41 PtCo

6.      42 PtCo

8. 393 PtCo

 Ground water sample; reason why the PtCo is very high. 

Analyze of the nitrate type

For analyzing the type of nitrate, we used also the HACH 2800 spectrophotometer, program number 353 and the wavelength 400 nm. We reset the cuvettes by themselves and did these one by another. After the reset, we added NitraVer 5 Nitrate reagent powder and placed parafilm on it to be able to shake it properly for one minute and waited for five minutes before measuring the result of the nitrate.

The results of the nitrate

Group 5

1.      0,1

2.      0,1

3.      0,1

7.      0,117

Group 7

4.      0,2

5.      0,1

6.      0,192

8.      0,336

Samples 6 and 7 were under measuring range 0,23-13,50 mg/l NO3 –N.

Turbidity determinations

For turbidity determination we used Turbidmeter HACH 2100N IS. We poured the samples to turbidity cuvettes and waited until the result stabilize. We wrote down the result by one decimal. Lastly, we washed all the sample cuves by 10% saline and deionized water.

The results of turbidity

Group 5

1.      1,1 NTU

2.      0,9 NTU

3.      0,6 NTU

7.      1,0 NTU

Group 7

4.      0,7 NTU

5.      1,9 NTU

6.      0,6 NTU

8.      43,0 NTU