[sweetyee]

Hi all

In general, we are familiar with the usual water samples dilution where for e.g final volume of sample analyzed(ml)/initial volume of sample (ml) will give the value of the dilution factor. How about oil samples i.e. diesel or lube oil. If we were to take e.g 0.5000 g of oil sample n diluted with a solvent to the mark of any volumetric flsk, can we calculate the dilution factor the same manner as water samples? E.g. 5ml/ 0.5000g =10 x dilution. Same applies to solid samples. Can we also assume that it is 1000x of dilution when 1 g of solid is being dissolved in 1L of solvent? Please advise.

[Arkcon]

Generally, we assume so yes.  But there are caveats -- volumetric flasks are probably OK, but I'm not absolutely sure.  Volumetric pipettes are very different, they are calibrated to the surface tension of water, and that is very different for most solvents -- they may run all the way out of a "to deliver" pipette that's meant to hold a little fluid.  Also, you'll have to consider that some mixed solvents don't have additive volumes.  For example a 100 ml graduate of ethanol and a 100 ml graduate of water don't mix into 200 ml of mixed liquid, as just one example.

Basically, you'll have to follow a published method that's standardized across the users of this information.  Or you can just do everything by mass.  Or you can do it both ways, verify (validate) that there's no difference, and then document how you'll do things in the future.

[JGK]

Hi all

In general, we are familiar with the usual water samples dilution where for e.g final volume of sample analyzed(ml)/initial volume of sample (ml) will give the value of the dilution factor. How about oil samples i.e. diesel or lube oil. If we were to take e.g 0.5000 g of oil sample n diluted with a solvent to the mark of any volumetric flsk, can we calculate the dilution factor the same manner as water samples? E.g. 5ml/ 0.5000g =10 x dilution. Same applies to solid samples. Can we also assume that it is 1000x of dilution when 1 g of solid is being dissolved in 1L of solvent? Please advise.

Better to do it by mass all the way through ie 0.5 g of oil diluted to 5 g final weight. It is very unlikely that your oil and solvent will be the same density.