8270 SVOA Internal Standard from Neat Compounds

[Darber99]

Has anyone ever made their own Internal STD for EPA8270 from neat compounds? I'm trying to make a 4000ppm SV Internal standard solution in DCM and everything goes into solution fine except for Perylene-d12. Even after 25 minutes of sonication, I still have some undissolved powder in the bottom of my volumetric flask. A last ditch effort seems to be heating the solution up to almost boiling and hoping the remaing solid dissolves, but I'm worried about losing some of my low boilers (1,4-DCB-d4, Naph-d8). Any suggestions? Thanks for your time.

[Yama001]

Our folks do it routinely - they tell me they just use an ultra-sonic bath. That being said, I often see lousy variations in the internal standard mixes they make up, so I bet they have more trouble with this issue than they will admit.

[Darber99]

Thanks Yama. That's exactly what I've been doing but it takes about 20-30 minutes of sonication and a good half day sitting at room temperature for all the Perylene-d12 to dissolve back into solution. Guess I should just be happy it does.