This from the forum archive, I think it will help you:

Yes, you CAN test it. Somewhere around here is the work I did last summer on this.

If you add (as I remember) 1.8ml of bleach to a 5 gallon bucket of NON-pool water, you can test the concentration.

The idea is that if one gallon of 6% bleach adds 6ppm of FC to 10,000 gallons, then 1.8ml (?) adds the same concentration to 5 gallons.

If you simply do the division and conversion it works.

And if you do it ALL in metric, then 1ml of bleach added to 10 liters of water should give you the same 1 : 10,000 concentration.

Then you measure the bucket the same as the pool and the result is the concentration in the bleach bottle.