up to this point we've been talking about gas liquid chromatography which is shortened to just gc the other type is gas solid so gas solid chromatography is based upon adsorption of gaseous molecules on a solid surface the distribution coefficients or k for gas solid are much larger than those for gas liquid chromatography meaning you get a greater separation of concentration between your stationary phase and your mobile phase gas solid chromatography is useful for separation of species not retained by gas liquid columns so this is components of air hydrogen sulfide carbon disulfide nitrogen oxides carbon monoxide carbon dioxide and many of your rare gases is performed with both packed and open tubular columns and for open tubular columns the thin layer of adsorbent affixed to the inner wall um so you're typically going to see your plot columns there's two types of adsorbents encountered with gas solid chromatography the first one is molecular sieves and so you have aluminum silicate ion exchanger and some molecules are like these little balls if you want to think of it that way and so here's an example of where you would have aluminum silicate forming that balls and it's going to be used to act as an ion exchanger a change between your mobile phase ions and this is your stationary phase ions the pore size depends upon the cation present so most commercials are going to be either 4 5 10 or 13 angstroms and then molecules smaller than the dimensions penetrate into the interior of the particles where adsorption is going to take place your other type is going to be porous polymers and so here porous polymer beads are manufactured from styrene cross linked with divinely benzene the pore size is uniform and controlled by the amount of cross linking and this is useful for separation of gaseous polar species such as your hydrogen sulfide oxides and nitrogen water and carbon dioxide methanol and vinyl chloride here's an example of a spectrum so typical gas spectrum separation so the first one is looking at 5 by 1 8 micro molecular sieve column versus the plot column so there's two types of columns used one is going to be your ordinary gas liquid column and one is a molecular sieve column so on the left here we're looking at an exhaust mixture so you're looking at the different components of the exhaust so a gas liquid column retains only carbon dioxide and passes all the remaining gases through so here you can see our carbon dioxide is b and so here yes carbon dioxide is b you see that here so in a typical column it's going to retain all the co2 pass everything else through and here you're going to get that separation that you would not normally see in a gas liquid chromatography when co2 is alluded from the first column you're going to switch direct flow around the second column briefly to avoid permanent absorption of co2 on the sieves so here's going to be our sieves and here's going to be our plot column so it's going to once that co2 elutes from the first column you're going to switch so it goes around second column if you have absorption of co2 onto your sieves it's going to permanently destroy it or permanently be on there after the co2 signal is returned to zero the flow is switched back through the second column permitting separation evolution of the remainder of the sample components so it's going to be using the two columns in conjunction ordinary gas liquid column and then a molecular sieve column and then in doing so so that's all for this left side and then in doing so you're going to have switching back and forth between the gas liquid and the sieves so that you can get that extraction without your co2 completely destroyed or being retained on those sips this one right here is going to be your plat column and so this is going to be a typical application of open tubular column lined with the porous polymer or your plot column and you see that separation here