Dave0

Hi Chaps. Thanks for that. I've got that squared off in my head now. I was over complicating it. Follow up question then. I am normally use to a stock solution expressing concentration as ug/mg and quoting its density. From which if I take a weighted aliquot (g) out of it I can convert that to ml by dividing it by the density. I have just received a cert for a stock solution that quotes 1003ug/ml and also 997ug/g. So obviously this saves me the bother of the correction above because it is telling me from the off what is in it if I decide to do a aliquot by volume or mass anyway. It does fail to quote the density of the solution which I don't need but I was wondering if I can work it out based on the two concentrations?

Hi. Newbie. First post. I am hoping someone can clear something up for me. If my stock is in w/v i.e. 100 ug/ml do I have to take my aliquot in the same unit/form i.e. w/v? What happens if I did an aliquot by volume with a pippette and then made it up the desired volume. That would be v/v. Do I have to apply a conversion? Please help. Dave.