Most work is done on DB-5 type of columns. I have not luck even on finding typical alkanes on Wax. I appreciate any advice!
Oh, thanks, I just check their web database and depending on the compound, they provide different indexes. However, KI for alkanes in polar columns is still missing....
Giselle,
for n-alkanes it is always 100* number of carbons.
For i-alkanes - probably it is not needed because Wax is used for polar compounds. If you need effective separation of n and iso alkanes take 100% PDMS column - check DHA ASTM method.
Regards
G
Grzegorz Boczkaj thanks! In reality, I am using alkanes for both columns DB-5 and SupelcoWax, to be more precise in analyzing non-polar and medium polar fractions of a SiO2 separation of a plant extract. The certainty of databases (Wiley and NIST) sometimes falls into the range of 70-80%, and in some rare cases, gives multiple hits above 95% of two or three components.
But in order to verify how well my temperature ramp is working, I wanted to verify the databases suggestions with RI or KI. Again, with DB-5, no problem. The problem is with SupelcoWax...
One of the useful properties of ret.index is that they don't change with value of the ramp - they will be the same for 5deg/min and 15deg/min (generally) - i.e. it is a retention relative to n-alkanes.
Remember that different formula is used for isothermal RI (Kovats) and different one for temperature program (LRI).
regards,
GB
Dear Giselle
If you are trying to get the databases of Kovats Indexes for polar columns by MassHunter (B.09.00) software with NIST 2017, It´s not possible. Please, check this question in Agilent Community.
The response was " As you observed the Library RI values shown in Unknowns Analysis are the same as the estimated non-polar retention indices found in the NIST library. There is no way to select any other column types in current (B.09.00) software nor will it be in the next release of Quant/Unknowns Analysis. The issue is under consideration for a future release. "
This is the link
https://community.agilent.com/thread/2040-linear-retention-indeces-masshunter-quantitative-analysis
Regards
- Badges
- Science topic
- Similar topics
- Indexes