Diammonium hydrogen citrate

Culture media containing 5, 10, 15 and 20 mmol/L sodium oxalate (MERK; Darmstadt, Germany) was prepared by adding 10 mL of the 0.46 μ filter sterilized sugar and ammonium oxalate solutions listed below to 10 mL base media proteose peptone no. 3 (MERK; Darmstadt, Germany), 10 g yeast extract (MERK; Darmstadt, Germany), 5 g Tween 80 (MERK; Darmstadt, Germany) 1 mL KH₂PO₄ (MERK; Darmstadt, Germany) 2 g Na acetate (MERK; Darmstadt, Germany) 5 g di-Ammonium hydrogen-citrate (MERK; Darmstadt, Germany) 2 g MgSO₄.7H₂O (MERK; Darmstadt, Germany) 0.05 g MnSO₄ (Merck) 0.05 g water to 500 mL and sterilized at 121°C for 15 min.
For the preparation of 5, 10, 15 and 20 mmol/L sodium oxalate solutions, 13.39 g of Na₂C₂O₄ (MW =133.96) transferred to a 100mL volumetric flask. Rinsed the boat into the flask through a funnel until the volume reaches to 100ml. It may need to heat this gently (NOT BOIL) to promote the dissolving. Then before autoclave sterilization of base media samples, a specified volume of sodium oxalate solution was added to the samples. The amount of sodium oxalate was derived from Eq 1:
$${\text{C}}_1{\text{V}}_1={\text{C}}_2{\text{V}}_2$$
C₁V₁ = Concentration/amount (start) and Volume (start)
C₂V₂ = Concentration/amount (final) and Volume (final)
The required volume of sodium oxalate solution with (20 mmol/L concentration) to the 10 ml base media derived from Eq. 1.