Gas chromatography and its graph

[AwayFromReality]

So I was reading through TBR's explanation of this process and came across something strange

"GC output is continuous, so the graphs are actually read from right to left, where signals on the right represent components with smaller elution times than components on the left. To determine purity of a product mixture, the graph can be read directly"

The first part confused me because if we look at a retention time (x-value) vs. intensity (y-value) graph a longer retention time would normally mean the gas spent a longer time in the column and therefore had a longer elution time. But the description above would imply the opposite.

Can anyone explain what TBR meant?

---

Members don't see this ad.

 

[DrknoSDN]

Can't be certain but i believe it is just referencing the very old gas chromatograms which were plotted with zero time on the far right, and time goes up as you move left along the axis.

I think once computers became a thing, it's more common to see time increase to the right.

Reference: link

 

[AwayFromReality]

Can't be certain but i believe it is just referencing the very old gas chromatograms which were plotted with zero time on the far right, and time goes up as you move left along the axis.

I think once computers became a thing, it's more common to see time increase to the right.

Reference: link

Thanks, I think that's probably what they were talking about. It strange that TBR mentioned this old method in the book and then showed the regular retention time vs intensity graph