Method Development – But Not as We Know It
Posted on May 27th, 2015
Last week was SIFT-MS workshop week and we had a full house of customers in the lab, most of whom were learning about Selected Ion Flow Tube – Mass Spectrometry (SIFT-MS) for the first time.
One customer, unexpectedly, brought with him some canisters containing standard mixtures of two fairly exotic volatile organics in air; at the end of the afternoon session, he asked to see if our SYFT Voice200Ultra could detect the two compounds contained in his cylinders.
Had we been asked to do this by GC-MS, in the very limited time available, we wouldn’t have got very far, however, as everyone is beginning to appreciate, everything to do with SIFT-MS is fast – including method development.
This is how we approached the challenge:
- We checked for the two compounds in the instrument’s compound library; unsurprisingly, they were absent.
- We looked in the NIST WebBook and found data on both of the compounds. NIST told us that both had an ionisation potential less than 12.1 eV, which in turn told us that that at least one of our reagent ions (O2+) would react with both compounds.
- We ran a sample in scan mode and found credible product ions for both compounds.
- In the instrument’s library, we found some other compounds with a similar functionality to the target’s and used these reaction rates as a benchmark to guess the reaction rates for our compounds. Using this informed guess, we created fresh library entries for the two compounds.
- We then measured the concentration of the targets in the two samples.
In one of the standards the two compounds were present at 500ppbv and in the other at only 5ppbv. In each case, despite having to guess the reaction rates for both – we measured the concentration of the customer’s samples and got within 25% of the true value.
This was a pretty remarkable achievement. Without a standard, we would not have been able to do this at all with GC-MS.
But there was something else that had everyone’s eyebrows raised: from start to finish, the whole process I have described took less than 15 minutes!
Speaking with the workshop attendees afterwards, in addition to the speed of SIFT-MS, there were two other major points that were commonly mentioned:
- The great versatility of the SIFT-MS – had peoples brains buzzing with the possibilities.
- SIFT-MS is very simple to use and could have great use making measurements on the factory floor.
If you would like to see our SIFT-MS in action on your samples, or would like to be kept informed of our next series of SIFT-MS workshops, please call us on +44 (0)1223 279210 or email: firstname.lastname@example.org.