Chromatography Forum

Hello,
I'm running soem complex essential oil mixes by GCMS and routinely search the EI spectra against the NISt and Wiley 7 databases. I notice that if I use NISt MS Search (v2.0), that I can get a large list of Kovats Index RI information for candidate hits. However, for the compounds I'm searching (mostly terpenes), the returned list of Kovats index data can be in the hundreds, where each entry is a summary of user-contributed system information (column type, column class, active pahse, column length, etc) for the Kovats index value obtained. This list is too long to be browsed easily

What I would ideally like is to only look at the top 2 or 3 Kovats values that match most closely the column and conditions I am using. This would mean filtering the Kovats index list by inputtable criteria that would compare against the user-contibuted system information.

Has anyone worked out a way to do this?

thanks
Tony

What manufacturer GCMS are you using? We have Agilent, and about 10 years ago we modified one of the data analysis macros to give us Retention Index from our own custom Search Library in the automated peak-searching report instead of the CAS number - is that what you're asking? Anyway, I know it works for 5971 and 5972 software, haven't tried that with our newer-software systems.

We are using ChromaTof on a Leco instrument. This software can return an RI field from a custom library (where the RI field is specified). However, the RI data already present in NIST 05 is not accessible this way. In NIST 05 the RI data is returned when present for each hit - but this may be tens or hundreds of different RI values per hit. It is nice to have all this data but frustrating to not be able to easily search or filter it.

I am looking for a way to quickly get to the best representative RI value compared to my column and conditions.

thanks
Tony