TLC and photosynthetic pigments

When carrying this out why:
-does the bottle have to sit upright and not at an angle
-why is the TLC strip not allowed to touch the sides of the glass tube
-why can I not move the bottle as solvent is running
-how do I prop the TLC strip inside the glass tube

You haven't provided a great deal of information, but I'll try to work with what you've provided:

1. Why does the bottle have to sit upright and not at an angle?

In any investigation involving thin layer chromatography, you will be required to calculate the Rf value for each, in this case, pigment involved by dividing the distance travelled by the pigment by the distance travelled by the solvent. This means the bottle must be sat upright and not at an angle to ensure both the solvent and pigment travels perfectly upwards with respect to the marked pencil line, ultimately to allow an accurate measurement of the distance travelled by the solvent and the pigments.

2. Why is the TLC strip not allowed to touch the sides of the glass tube?

The TLC strip must not touch the sides of the glass tube to ensure it does not bend during a solvent run and to ensure the pigments run in a straight line, again relating to accurate measurements to produce a true Rf value of the pigments involved.

3. Why can I not move the bottle as solvent is running?

Again, moving the bottle during a solvent run will affect the angle at which the solvent travels and also the distance it travels. Similarly, moving the bottle may produce 'noise' on the TLC strip, making it more difficult to measure the distance travelled by both the solvent and the pigments.

4. How do I prop the TLC strip inside the glass tube?

The TLC strip may be propped inside the glass tube using a perfectly horizontal bar and a clip, provided the bar and clip does not interfere or impede the distance travelled by both the solvent and the pigments. This set up can be illustrated as follows:



Tried to work with the information you provided, hope this helps.

Thankyou also when measuring the Rf where do I draw the line where the pigment is? At the top, through the centre?