Sample Experimental Section (written for experiment 6)
All glassware used in this experiment was rinsed with 1 M HCl (aq) followed by Type 2 water prior to use.
Transfer pipettes and volumetric flasks were all Grade A. Aqueous solutions were prepared with Type 2 water.
%transmittance was measured using a Spectronic 20D+ Spectrophotometer and a single 10 mm borosilicate
Creek Water Acid Digestion:
50 mL of creek water collected from Location A was pipetted into a 250 mL beaker using a 25 mL transfer
pipette. 2 mL of concentrated HCl was then added via a transfer pipette and the sample was brought to a
gentle boil using a hot plate. After boiling for 20 minutes, the sample volume had been reduced to
approximately 20 mL. The acidified sample was removed from the hot plate and allowed to cool to room
temperature. After confirming that no solid particles were visible, the sample was quantitatively transferred to
a 50 mL volumetric flask. The flask was filled to the mark with water and the sample was then transferred to a
clean and dry polyethylene bottle for storage for one week.
Creek Water Sample Preparation:
A 50 mL creek water sample was prepared by pipetting 25 mL of the digested creek water sample into a
volumetric flask using a transfer pipette. This was followed by the sequential addition of 1 mL of 10%
NH 2H•HCl (measured with a graduated cylinder) and 5 mL of 0.1% 1,10-phenanthronline (measured with a
graduated cylinder). 5.25 mL of 2.000 M NaOH was then added using a 5 mL transfer pipette and a
micropipette. Lastly, 1000 µL of 1.0 M sodium acetate was added via a micropipette. The flask was filled to just
below the mark with water, mixed well, and the pH tested using narrow range (3.0-5.5) pH paper. After
confirming that the pH was between 3.5 and 4.5, the flask was further filled to the mark. The solution was left
to stand for 10 minutes before the %transmittanc