Experiment 1: Samples

Student filtering Santa Ana River water sample.

Calibration Standards

Potassium Hydrogen Pthalate (KHP)

Concentration Range: 0.5, 1, 2, 3, 4, 5, 10 mg/L C

Salicylic Acid: [TOC] = 5 mg/L as C

Filtered Water: 0.45 um Whatman GF-C glass filter
Unfiltered Water
Glutamic Acid (HOOCCH₂CH₂CCHCOO- NH₃+) - [TOC] = 2 mg/L as C

Sample preparation was not necessary since the sample concentrations fell within the prepared standard curve. In order to determince the particulate organic carbon concentration in the wetlands sample, the sample did have to be filtered. It was necessary to make sure that the filter was rinsed with ultrapure water several times before the sample was filtered, since the filters can leach carbon.

The glutamic acid sample with a concentration of 2 ppm C and the salicylic acid sample with a concentration of 5 ppm C had to be prepared. A stock solution of 20 ppm glutamic acid was prepared by adding 9.809 mg to 200 mL of water. Then 10 mL of the 20 ppm was added to 90 mL of ultrapure water. A stock solution of 50 ppm salicylic acid was prepared by adding 16.4423 mg of salicylic acid to 200 mL of water. Once again 10 mL of the stock solution was added to 90 mL of ultrapure water.

The potassium persulfate reagent solution had to be prepared for the analyzer. This was made by dissolving 20 grams of sodium persulfate in ultrapure water. To this solution, 2 mL of phosphoric acid was added, and the solution was stirred. Great precision was not necessary in making this solution, ± 5%. The solution was kept in a glass bottle since plastic can leach carbon; however, any carbon that was present would show up as a background concentration and would not affect the sample readings.

Prado Wetlands Santa Ana River
Histosol Soil Extract, 17.5% TOC