I have been using a mass spectrometer Shimadzu GCMS-QP2010MS-DIAL for GC-MS-based untargeted metabolomics.
I have two questions about processing by MS-DIAL:
- For compounds identification, what is the best MSP file?
- What "RI tolerance" should I use?
>>For compounds identification, what is the best MSP file?
It's up to your GC condition.
If there are no equal system in the following website, please use 'all records with Kovats RI' if you use alkane mixture.
http://prime.psc.riken.jp/compms/msdial/main.html#MSP
>>What "RI tolerance" should I use?
basically, I am using 5 RI tolerance in using alkane mixture.
I hope that this information is helpful for you.
I think, the best way is to follow a method which has already been published in a journal.
Hiroshi
Hi Hiroshi.
Thank you for help me.
I have been using alkanes mix for identification of compounds. Why the RI values (reference) for the file 'all records with Kovats RI' are higher than ADAMS records?
Example: Limonene MS-DIAL: RI (ref) 1233
ADAMS: RI (ref) 1029.5
Frederico
Sorry, what is ADAMS?
Sorry Hiroshi,
ADAMS is the author of the book: Identification of Essential Oil Components by Gas Chromatography/mass Spectrometry.
I have seen higher RI (ref) in MS-DIAL than in others platform like this one: https://webbook.nist.gov/chemistry/.
Frederico
Hi Frederico,
there are two reasons:
1. Some of records that I distributed have the predicted retention index values. So it may cause the differences.
See: https://pubs.acs.org/doi/abs/10.1021/acs.analchem.7b01010
2. It may be due to the difference of column polarity. What I distribute is basically that the records were obtained by DB-5. Did you check the column polarity used in ADAMS?
Thanks,
Hiroshi