We have blogged before about t0 and the importance of knowing when it is in terms of retention time when we go to evaluate forensic chromatography results. You can read it again here:
T0 (provided that the area reject-think of how Josh made those peaks disappear in front of your very eyes just this Saturday when we showed you good folks the software) has not been set artificially high should be there. It is not a product of error. It is a feature of success.
Think of it this way.
In 2008, there was a 100 meter race. The fastest person recorded on the planet Earth to cover this distance from a fair start is Usain Bolt. He crushed it. 9.69 s made others look like nothing. Remember this?
At the Olympics, no one could beat him. He was the fastest human capable of completing that distance. 9.69 s. No one could beat him.
The world record is like that t0 time. It is the fastest that anyone (or in the case of chromatography anything) can get through the race. In HS-GC-FID, it is the physical constraint. It is the time that it takes an unretained analyte to race through that column and make it to the detector (remember from injection to detector there is the column that the injection has to be pushed through by the carrier gas so it takes some amount of time).
Let’s suppose for argument’s sake, immediately right after that record breaking 100 meter race, Usain Bolt had to run another 100 meter race. But this time, I, as in Justin McShane, beat him. Impossible! Many if not most of you have met me. I’m short and fat. I’m not fleet afoot. The only way I could beat Usain Bolt is that I started before him. I cheated. I was in the last race, not this one. I carried over. It wasn’t a fair or just race. I contemned the second race.
It strikes that old time chromatography’s phrase, “just because you are done with the chromatography doesn’t mean that the chromatography is done with you.” Carryover is so important to understand. t0 is equally so