Iron standards

Reagents

• FerroVer® Iron Reagent Powder Pillows, 5 mL, Hach, Part # 92799, $17.59 for 100 tests

• Iron standard, 200 ppm, Labchem Part # LC157207, $22.90 for 125 mL

• Distilled water

Equipment

List of vendors and prices: https://sites.google.com/iorodeo.com/colorimeter/equipment

• Colorimeter with RGB board (use blue for measurement)

• Cuvettes

• 1 x 50 mL capped tube

• 9 x 10 mL capped tubes

• Pippete pump

• 2 mL, 5 mL, 10 mL pipettes

Prepare calibration solutions

• Prepare 20 mL of a 12.5 ppm working stock as follows: In a 50 mL tube, add 1.25 mL of 200 ppm standard and 18.75 mL of distilled water. Mix

• Dilute the working stock as outlined in the Table below

Method

• To each 5 mL sample, add the contents of one FerroVer iron reagent powder pillow, shake and let stand. An image of all of the calibration solutions after adding the powder reagent is shown above.

• Transfer approx. 1mL of each calibration solution to a cuvette.

• In the colorimeter plotting program, select the blue LED and ppm as units. Calibrate the colorimeter with the 0 ppm iron solution and measure absorbance of all of the solutions in duplicate.

Sample calibration data

• Sample calibration data: iron_hach.txt

• To view/use: Download the file and open in the colorimeter plotting software as described here.

• Calibration curve measurements were repeated three times with 3 new working stock dilutions. Data for the three separate calibration trials were compiled into one file. A plot for all three sets of data is shown in the graph below