Determining the Presence and Concentration of Contaminants in Local Water Supplies

Steven Donmoyer, Cody Lloyd, Matthew Maple

Water was collected from four different locations during three consecutive weeks in Lebanon County and tested for a variety of contaminants. The locations were a well on a farm in Lebanon County, a stream beside the aforementioned farm, the Quittapahilla “river” running through Annville, and a water fountain on the ground floor of the Neidig-Garber science building. The tests being run on the contaminants are a range of colorimetric tests to determine the concentrations and presence of nitrates, nitrites, iron, and phosphates; EDTA-titrations are also going to be run in order to determine the concentration of carbonates in each of water samples.

Inorganic Contaminants Being Identified

Mg2+

Nitrate Nitrite Phosphate

Hard Water Carbonates

Tests being performed on the water samples include pH testing, colorimetric testing to determine the presence of inorganic molecules, NMR to determine carbonates/organic molecules, and titrations to determine the concentration of hard water carbonates

Experimental Methods

Determination of Phosphate Concentration Determination of Iron ContentFe (III) is a highly reactive metal ion. When

reacted with salicylic acid, a purple complex is formed. This purple color signifies that a phenol is present, but also that Fe (III) is present, or not present. A standard Fe (III) solution was created to be 6.22 x 10-7 M, which represents the maximum amount of Fe(III) allowed in water supplies by the EPA. This amount of Fe (III) turned a 1 x 10-3 M salicylic acid solution a lavender color, indicating that if there is any Fe (III) in the water, it would become purple.

Future Determination of Hardness, pH and Nitrogen Concentration

*

= 0.3 ppm Fe (III)

The colored liquid on the left that is slightly purple is the 0.3 ppm Fe(III) solution in salicylic acid. The right hand solution is one of the water samples from the barn well. The barn well samples, as well as all other samples, did not change color at all, indicating that there is no iFe(III) present in them that is a large enough amount to form the complex

Salicylic Acid Fe(III)-Salicylic Acid complex

760

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1060

0

0.05

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0.15

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0.25

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0.35

Sample Phosphate Absorbance vs. Wavelength

Barn 3-14 100%T Baseline Correc-tion 4/1/2014 10:56:42PM A

Barn 3-22 100%T Baseline Correc-tion 4/1/2014 10:54:55PM A

Barn 3-28 100%T Baseline Correc-tion 4/1/2014 10:59:03PM A

Crick 3-14 100%T Baseline Correc-tion 4/1/2014 10:40:29PM A

Crick 3-22 100%T Baseline Correc-tion 4/1/2014 10:44:37PM A

Crick 3-28 100%T Baseline Correc-tion 4/1/2014 10:53:13PM A

NG 3-14 100%T Baseline Correction 4/1/2014 10:46:52PM A

NG 3-22 100%T Baseline Correction 4/1/2014 10:48:54PM A

NG 3-28 100%T Baseline Correction 4/1/2014 10:50:59PM A

Quit 3-14 100%T Baseline Correction 4/1/2014 11:01:27PM A

Quit 3-2 100%T Baseline Correction 4/1/2014 11:02:54PM A

Quit 3-28 100%T Baseline Correction 4/1/2014 11:04:08PM A

760 810 860 910 960 10100

0.05

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Standard Phosphate vs. Wavelength

0.04 ppm 100%T Baseline Correc-tion 4/1/2014 10:17:42PM A0.08 ppm 100%T Baseline Correc-tion 4/1/2014 10:22:25PM A0.12 ppm 100%T Baseline Correc-tion 4/1/2014 10:25:35PM A0.16 ppm 100%T Baseline Correc-tion 4/1/2014 10:33:19PM A0.20 ppm 100%T Baseline Correc-tion 4/1/2014 10:35:55PM A

Above is the combined spectrum of all samples tested for phosphate concentration. It was determined that the only source with a [PO4

3-] > 0.04 ppm is the NG 2nd floor water fountain, which had between 0.16 and 0.20 ppm across the board. All others had below the minimum standard curve value of 0.04 ppm.

Above is combined spectrum of all standard solutions run to generate a standard curve. Concentrations of [PO4

3-] were 0.04, 0.08, 0.12, 0.16, and 0.20 ppm. The curves increased in absorbance at 880nm and 990nm with increasing concentration.

Within the next month, additional tests will be run to determine the hardness, pH, and nitrate/nitrite concentration of each water sample. The following methods will be used for the experiments:

EDTA Titration will be utilized to determine the hardness of the water samples. The above equation will be used to determine the amount of carbonates in the samples.

Ca+2 + EDTA-4 ------> CaEDTA-2

pH meters will be utilized to determine the pH of the samples. The image to the right shows the type of meter that will be used: HM Digital pH-200

pH Determination

AcknowledgementsLVC Professors Dr. Marsh, Professor Horne, Dr. Patton

Sigma-Aldrich Chemical Company

Nitrate/Nitrite DeterminationNO3- + H,O + EDTA4-+ CdO - NO*- -t 20H- + Cd(EDTA)'-

The above equation is the method for reducing all nitrate to nitrite in what is called the Cadmium Reduction Method. In this method, all nitrogen containing compounds are reduced o nitrite and turned into a diazotrope via N-(1-naphthyl-ethylenediamine dihydrochloride and sulfanilamine, the above molecule. This molecule can be analyzed via UV/Vis spectrophotometry

To test for phosphate ion concentration in the samples, 5 standards were created and run on the UV/Vis spectrophotometer via an ascorbic acid colorimetric reaction