Calcium Standards
Reagents
Calcium Hardness solutions CH1 and CH2, LaMotte # 7042-G and 7041-G
Calcium Reference Standard Solution, 1000 ppb, Hach part # 2240349
Distilled water
Equipment
List of vendors and prices: https://sites.google.com/iorodeo.com/colorimeter/equipment
Colorimeter with custom 575 nm board
Cuvettes
1 x 50 mL capped tubes
9 x 10 mL capped tubes
Pippete pump
5 mL, 10 mL pipettes
Prepare Calibration Solutions
Prepare 20 mL of a 250 ppm working stock from the 1,000 ppm calcium standard: add 5 mL of standard to 15 mL of distilled water. Mix.
Dilute the working stock as outlined in the Table below
Method
To each 5 mL sample, add 5 drops of CH1, mix then add 5 drops of CH2. An image of all of the calibration solutions after the reagents is shown above (to be added).
Transfer approx. 1mL of each calibration solution to a cuvette.
In the colorimeter plotting program, select the 575 nm LED and ppm as units. Calibrate the colorimeter with the 0 ppm calcium solution and measure absorbance of all of the solutions in duplicate.
Sample calibration data
To view/use: Download the file and open in the colorimeter plotting software as described here.