1.Zero Turbidity water : Filter distilled water through a 0.2μm filter membrane and collect it in a glass bottle washed twice with filtered water.
2.Hydrazine sulfate solution (1g/100mL): Weigh 1.000g of hydrazine sulfate (AR) and dissolve it in zero degree water, and dilute to 100mL.
3.Hexamethyltetramine solution (10g/100mL): Weigh 10.00g hexamethylenetetramine (AR) and dissolve it in Zero Turbidity water, and dilute to 100mL.
4.Turbidity standard stock solution: accurately pipette 5.00mL hydrazine sulfate solution and 5.00mL hexamethylenetetramine solution into a 100mL volumetric flask, and mix it evenly.
Let it stand at (25±3)℃ for 24h, then dilute it to 100ml by Zero Turbidity Water after cooling to room temperature, and mix it evenly, Now The turbidity value of this solution is 400 NTU.the validity is 1 month.
Note:
1)If you need other turbidity standard solutions, you can use 400 NTU turbidity solution for dilution to achieve the required turbidity.
2)Example to get 20NTU turbidity standard solution: Take 5ml of 400NTU standard solution into a 100ml volumetric flask, dilute to the mark with pure water, and mix well.