Internal Stds

[itsbourne]

Hi,

We are trying for make naphthalene solution of 20ppm in DCM. When we analyse it in GCMS the conc. shown is 30% less around (14ppm).
This is consistent with several other solutions prepared with different solvents. Is this due to problem with GCMS?

Can it be fixed using internal stds?

Thanks
Jason

[Consumer Products Guy]

I'd use a solvent less volatile than DCM.

or use HPLC

[Peter Apps]

Hi,

We are trying for make naphthalene solution of 20ppm in DCM. When we analyse it in GCMS the conc. shown is 30% less around (14ppm).
This is consistent with several other solutions prepared with different solvents. Is this due to problem with GCMS?

Can it be fixed using internal stds?

Thanks
Jason

How do you know that the concentration is "14 ppm" ?

Please do us all and yourself a favour and use proper units - the density of DCM is 1.3 g/ml, so if you are mixing up volumes and masses in calculating your "ppm" the problem disappears.

Peter