Chromatography Forum

I want to make a method for toluene diisocyanates on GC-MS. I tried a standard solution and it gives me signal, but how can I be sure that the method will be ok when I will analyze environmental samples (usually air, sampled on special absorbent tubes for TDI without derivation ?

the signal is at the same retention time for several injection, and the area is growing with the concentration

thanks for any thought

.....I will analyze environmental samples (usually air, sampled on special absorbent tubes for TDI without derivation ?...

What are the concentrations of interest?

Most of the people analyzing isocyanates at low concentration use derivatization because of the instability of the NCO group. Generally the isocyanate is transformed in urea and analyzed by liquid chromatography (HPLC-UV, HPLC-FLD, LC-MS or LC-MS-MS). I think to remember GC-MS methods but always using derivatization.

bhuvfe

[/quote]What are the concentrations of interest? [quote]


there will be low concentrations (ug/l)

What are the concentrations of interest?

there will be low concentrations (ug/l)

If you have no access to LC a way might be using an impinger with water and after a certain time you can derivatize the solution with a perfluorinated anhydride and extract the solution with an appropriate solvent for the GC-MS. I think there's some literature available about this. The only disadvantage is that you monitor TDI as sum of TDA+TDI originally present in the sample.

Good luck.
bhuvfe

What are the concentrations of interest?

there will be low concentrations (ug/l)

If you have no access to LC a way might be using an impinger with water and after a certain time you can derivatize the solution with a perfluorinated anhydride and extract the solution with an appropriate solvent for the GC-MS. I think there's some literature available about this. The only disadvantage is that you monitor TDI as sum of TDA+TDI originally present in the sample.

Good luck.
bhuvfe

Thanks

I will need it