This does not directly answer your question, but may be useful:Aviagen reccomends 8-16mg/lb body weight.
Actually, it sometimes means adding more than a liter of water.
When mixed with water, some materials actually decrease the total volume.
Ethanol is notorious for messing with final volume, but other substances can do so as well.
Does anyone have access to a copy of the USP/NF? Or the EP? or the JP? All three pharmacopeia will tell you how to prepare solutions as approved for use, which would settle this pretty quickly. Any pharmaceutical chemists out there (I was one, but I went back to school!)
FWIW, barring any other information, I would make the solution with 135 g of solid, plus 1000mL water, added to a container and dissolved.
Agreed that you should follow the industry-recognized standard method for preparation of solutions. What’s most important is that everyone follow the same convention.
That being said, a thought occurred to me while working out last night: The units don’t actually work out for w/v %.
For w/w %, it doesn’t matter what mass/weight units you use (e.g. grams, mg, lb, etc.), so long as you use the same units for the solute and solution. The same is true for v/v %. It doesn’t matter what volume units you use (e.g. mL, gallons, etc.), so long as you use the same units for the solute and solution.
However, for w/v %, this is not true. Generally, grams are used for the mass of solute, and mL are used for the volume of solution. These units do not properly cancel to give a percentage.
The only reason it generally gives a reasonable approximation is because 1 g of aqueous solution has a volume of approximately 1 mL. However, this approximation becomes increasingly inaccurate for concentrated solutions.
IMHO, it would be more accurate and less confusing to simply leave the units in place (e.g. g/mL) than to try to express it as a percentage–or use w/w %.