Of course weighing the material is the best method,if one has access to a decent scale.
I thought measuring/mixing was the issue, as NaN had addressed the suggested "1000 ppm solution" at the very beginning of this thread. (Sorry, apparently I misunderstood what you were asking...)
Although I would start with the lesser concentration suggested (500ppm or even half that) & work up from there, or simply make a batch of the high concentration (1000ppm) mixture, separate it into small amounts & dilute a few of them in different amounts, to create different PPM batches for trial.)
The site claims (with many mis-spelled words) "The intructions sheets that come with heach product indicate how much fits into a scoop."
(Or in plain English: "The instruction sheet that comes with each product will indicate how much (grams) fits into a scoop.")
Having the instructions would have solved the "mixing" issue from the very start.
I looked around the thread here but didn't notice... What indeed happened to the instruction sheet?
If they didn't send one, they need contacting about it! If for no other reason than to inform them that they need to get their act together, lest other growers run into the same issue.
By the way, if you can weigh out 1 gram (or less) as you now mention doing, then there was apparently no problem mixing/measuring to begin with. I thought that was part of the problem, that you couldn't weigh the powder out. Again, sorry, my mistake.
Also, the weight (# of grams) the scoop (1/32 tsp) ultimately holds, can only be determined by the material that is in it (Specific gravity/specific weight).
[One tsp. of lead weighs more than one tsp. of water.]
Bottom line, find the instructions they sent, get a scale, or contact the company to get a copy of the instructions they didn't send the first time.
MacD?!