Method F-002F The Determination of Calcium in Beer

Equipment Required:

1. Sherwood Model 410 Flame photometer with calcium filter
2. Graduated stoppered centrifuge tube

Reagents:

1. Standard calcium solution 1000 mg/l (Sherwood Part 00156623)
2. 1% ammonium oxalate solution
3. 0.5% ammonium oxalate solution
4. 25% ammonia solution
5. 4M perchloric acid

Reagents Preparation:

1. Dissolve 12.6g (C00H)2 2H₂0 to 1 litre distilled water in a volumetric flask. This is 0.1 M oxalic acid.
2. Dissolve 12.2g (C00NH₄)₂ H₂O to 1 litre of distilled water in a volumetric flask. This is 0.1 M ammonium oxalate.
3. To 5ml of 0.1 M oxalic acid in a 100ml volumetric flask add 0.1 M ammonium oxalate up to the mark.

Method:

1. Prepare the Ca Standard Solution by pipetting exactly 100 mls Ca standard solution into 1 litre volumetric flask and adding 50 ml 4M perchloric acid and dilute to the mark
2. Pipette 5ml beer into a 10ml graduated stoppered centrifuge tube.
3. Add 5mls 1% ammonium oxalate and 3 drops ammonia solution.
4. Shake, and allow to stand for 30 minutes.
5. Centrifuge at 2000 rpm for 2 minutes.
6. Decant the supernatant and allow the tube to drain inverted for 30 seconds.
7. Add 0.5ml 4M perchloric acid and shake.
8. Heat for 1 minute in a boiling water bath.
9. Cool and dilute to the mark with distilled water.
10. Set the Ca Filter into light path of M410 Flame Photometer
11. Calibrate the flame photometer using a 100 ppm Ca²⁺ standard by aspirating the solution and setting the display to read 100.
12. Without altering the settings aspirate the 60 and 40 ppm Ca²⁺ solutions which have been prepared by diluting the Ca standard soution and check linearity.
13. Aspirate the sample directly into the flame photometer.
14. The calcium concentration is then calculated by reading the Ca concentration from the standard curve, and multiplying the reading by the dilution.