Fr, 26.5.2023 | Original article from: Mass Spec Interpretation Services/James Little
The major emphasis was employing the NIST hybrid search for unknown identifications. However, in some cases “spectra-less” databases were shown to be very complementary.Unknown Identification Presentation at Current Trends in Seized Drugs Analysis Symposium
- Photo: James Little: Unknown Identification Presentation at Current Trends in Seized Drugs Analysis Symposium
- Video: James Little: Approaches for Identifying New Psychoactive Substances (NPS's) by EI Mass Spec Hybrid Searches
I presented a talk on approaches for the identification of seized drugs at the 2023 Current Trends in Seized Drug Analysis Symposium. The major emphasis was employing the NIST hybrid search for unknown identifications. However, in some cases “spectra-less” databases, such as the CAS Registry (SciFinder-n) and Chemspider, were shown to be very complementary to the hybrid search approach.
The presentation also included many links to detailed FREE tutorials detailing the use of the NIST search, Wiley KnowItAll, MS Interpreter, ChemSpider, and SciFinder-n (CAS Registry) software applications. Also, many other mass spectrometry resources were shared.
The handout below contains a copy of the slides from the talk and references with links to content on my web page.
ChemSpider is a “spectra-less” database to aid in the identifications using results from the NIST EI hybrid search and other analytical data. It is a free resource containing >50 million records with associated structures.
It is searched by molecular formula, monoisotopic mass, nominal mass, and substructure/similar structure. I have created a video demonstrating its use for the two different unknowns discussed in the main presentation.
James Little: Alternate Approach Using ChemSpider and the Hybrid Search Results
The CAS Registry (SciFinder-n) is another “spectra-less” database that can be used in the identifications process. It is a very powerful fee-based resource for accesing information from the highly curated CAS registry of >127 million records with associated structures.
t is searched by key phrases, substructure/similar structure, molecular weight, and molecular formula. I have created a video demonstrating its use for the two different unknowns discussed in the main presentation.
James Little: Alternate Approach Using SciFinder-n and the Hybrid Search Results
Excellent CAS SciFinder-n training videos are available on a variety of topics. I have links to a few essential videos that I captured below that will be very useful for the new user of this powerful software package. They have many more on their website.
- Basic Searching a Topic and Filtering
- Basic Structure Searches
- Searching for Specra and Properties of a Chemical
Conclusions
Hybrid search is a very valuable addition to the identification process
Extends the utility of all commercial and user EI and MSMS libraries
One of the “many tools in my toolkit” to identify unknowns including:
- “Spectra-less” databases
- IR data
- NMR data
- Accurate mass data
- Chemistry
In many cases, someone knows the identity of my unknown, I just need to find that information...
