N & P reference solutions

[PaulB]

i want to mnak up reference solutions to calibrate my NO3 & PO4 test kits. Does anyone know what quantity of KNO3 & KH2PO4 to use to make up base reference solutions with say 1lt of distilled water, which can then be diluted to make up 5, 10 & 20ppm NO3 solution and 1, 2 & 3ppm PO4 solution.

 

[neil1973]

1.433g of KH2PO4 will give 1000ppm PO4 in 1 litre of water.

1.631g of KNO3 will give 1000ppm of NO3 in 1 litre of water.

Regards
Neil

 

[Tom Barr]

Make sure you store these solutions in very tight sealing bottles.
Make what you need for a few times for the low concentrations.

1000ppm can be diluted by using 1ml of the 1000ppm into 9 mls of DI water.
Now you have 10mls of 100ppm NO3.

Now take 5 mls of the 100ppm NO2 solution and add 5mls of DI water.
Now you have:

999mls of 1000ppm NO3 solution
5 mls of 100ppm
10 mls 50ppm.

Take 1 ml of the 50ppm and add 9 mls of DI water, now you have 5ppm.

You can make up whatever concentration you want by going from high concentration to low concentration and dilute with DI water.


Regards,
Tom Barr

 

[Laith]

Here's what I use for NO3:

- Mix 4.1g of KNO3 in 500ml of RO water.
- 1ml of this solution in 1l of RO water should give you 5.03mg/l of NO3...

For example, 4ml of the initial mix in 1l of RO water should give you 20.12mg/l of NO3.