Hello, all. I'm writing a report based on a chromatography experiment we carried out. I'm posting some questions here as I know BCUK is fairly active although it's not bushcraft related, I know there are a folk on here who like their science!
This paragraph highlights what was found:
Firstly, it can be seen that a range of pigments exist within the examined Q. robur leaves. β-Carotene travelled the farthest with an Rf of 1.00 whilst chl-b travelled the least with an Rf of 0.14. Chl-a resides in the middle with an Rf of 0.27. The greater β-Carotene Rf value indicates that the pigment molecules have less of an affinity for the hydrophilic paper, are more soluble in the hydrophobic solvent and are less massive, whereas the smaller value for chl-b indicates the inverse. In regard to the unidentified red leaf an Rf of 0.33 was produced for chl-a and 0.14 for chl-b, values very similar to those found in the oak extract for the same pigments. Overall, the results consistently track the polarity of the pigment molecules from more polar chl-b to the intermediate chl-a through to the nonpolar hydrocarbon, β-Carotene.
Just in case you're wondering we used petroleum ether/acetone as our solvent at 9:1.
Questions. Why does the red leaf (we couldn't i.d it) not contain any form of carotenoid or why was it not drawn out? From my understanding, all plants should have carotenoids. What is the significance of the chl-a and chl-b Rf values being very similar to each other for both leaf extracts? I suppose it's because Rf values are constant in one particular solvent?
Edit: a separate question. We took our oak leaf from the bottom of a large tree in relative shade (as opposed to the more light exposed canopy). Now, PSII has a greater proportion of chl-b than chl-a and shade-adapted chloroplasts therefore have a higher ratio of PSII to PSI as chl-b increases the range of light absorbed. Does this have any bearing on the above results? In other words, does this principle apply to "localised" shade, e.g. shaded leaves on a single tree, or does it only apply to a plant always in full shade?
Any help would be much appreciated.
This paragraph highlights what was found:
Firstly, it can be seen that a range of pigments exist within the examined Q. robur leaves. β-Carotene travelled the farthest with an Rf of 1.00 whilst chl-b travelled the least with an Rf of 0.14. Chl-a resides in the middle with an Rf of 0.27. The greater β-Carotene Rf value indicates that the pigment molecules have less of an affinity for the hydrophilic paper, are more soluble in the hydrophobic solvent and are less massive, whereas the smaller value for chl-b indicates the inverse. In regard to the unidentified red leaf an Rf of 0.33 was produced for chl-a and 0.14 for chl-b, values very similar to those found in the oak extract for the same pigments. Overall, the results consistently track the polarity of the pigment molecules from more polar chl-b to the intermediate chl-a through to the nonpolar hydrocarbon, β-Carotene.
Just in case you're wondering we used petroleum ether/acetone as our solvent at 9:1.
Questions. Why does the red leaf (we couldn't i.d it) not contain any form of carotenoid or why was it not drawn out? From my understanding, all plants should have carotenoids. What is the significance of the chl-a and chl-b Rf values being very similar to each other for both leaf extracts? I suppose it's because Rf values are constant in one particular solvent?
Edit: a separate question. We took our oak leaf from the bottom of a large tree in relative shade (as opposed to the more light exposed canopy). Now, PSII has a greater proportion of chl-b than chl-a and shade-adapted chloroplasts therefore have a higher ratio of PSII to PSI as chl-b increases the range of light absorbed. Does this have any bearing on the above results? In other words, does this principle apply to "localised" shade, e.g. shaded leaves on a single tree, or does it only apply to a plant always in full shade?
Any help would be much appreciated.
Last edited:
