Extracting Molecules

After sitting in methanol for 24 hours, it was time to separate the algae from the solution.  To do this I used a Buchner flask and funnel. The flask is attached to a simple pump that lowers the pressure inside the flask and helps to pull solution through the filter paper in the funnel.  I tipped the solution into the funnel and then added the algae so as to retrieve as much solution as possible.  The solution (with the extracted molecules) ended up in the flask while the algae was trapped in the funnel.  The solution is called the first extract.

The algae was then returned to its original flask and more methanol was added to it (300 mL for the P. angustum, 500 mL for the P. microcladioides).  It was then left for another 24 hours so that more molecules could be extracted from the algae.

After 24 hours the algae was separated from the solution in the same way as above. The solution obtained this time is called the second extract.

We have now probably finished with the algae, but rather than throwing it out, the algae is placed in a bag and stored in a freezer.  This is so that it is still available in case we need to use it again later.

Meet the Algae

My molecule hunting exploits are going to be based on two species of red algae - Plocamium angustum (to the right) and Plocamium microcladioides (to the left).  These are both types of seaweed found in New Zealand waters.  They contain chloroplasts as they produce food by photosynthesis.  The red colour is due to  pigments in the algae.

My first task is to extract a mixture of molecules from the algae.  This done by chopping a sample of the algae into small pieces, putting the pieces into a conical flask and then covering them with methanol.  The methanol acts as a solvent which molecules from the algae dissolve into.

I used 48.1 g of P. angustum and needed 300 mL of methanol to cover it.  The P. microcladioides was a larger sample.  It had a mass of 97.8 g and required 500 mL of methanol to cover it.

The conical flasks were then covered in aluminium foil and put into a dark cupboard.  Why? Some of the molecules being extracted could be light-sensitive - they might break down into something else if exposed to too much light.  The flasks were left overnight.

Almost immediately the methanol started turning green (not red!).  The green colour is probably due to chlorophyll from the chloroplasts in the algae.

You may notice that the flask has a code written on it. 'BPM1' refers to my 1st lab book - my initials are BPM. (If you look carefully you will see that I accidentally left the '1' off). '01A' means that it contains sample A (my P. angustum) and information about it can be found on page 01 of my lab book. Our lab books have pre-numbered pages and also produce a carbon copy of each page.  The lab books stay in the lab so anybody can check what is in a flask by going to the relevant lab book.  They also provide a permanent record of all practical work undertaken in the lab.

Out of the Classroom

I can usually be found at Paraparaumu College where I get to teach lots of great students about science and chemistry. However, for the first half of this year I wont be at Paraparaumu College, but instead I am based in the School of Chemical and Physical Sciences at Victoria University of Wellington. I am here on an Endeavour Fellowship which is administered by the Royal Society of New Zealand.  Along with about 20 other primary and secondary school teachers from around the country I have been given the opportunity to step outside the classroom, roll up my sleeves and experience working with scientists on real science challenges.  It is a great opportunity for me to learn more about how scientists create new scientific knowledge and to expand my own chemical knowledge, skills and experiences.

I am working in a marine natural products lab under the supervision of Dr Rob Keyzers and Associate Professor Peter Northcote.  With me in the lab are several PhD and post-doctoral (have already got their PhD) students who are hunting for undiscovered molecules in things that live in the sea such as sponges and seaweed.  Why are they doing this?  Some of the molecules that are discovered may prove to have uses that are beneficial to people.  For example, a molecular compound may be effective at killing certain types of bacteria and could therefore potentially be used as an antibiotic.  Even for molecules that don't prove to have any immediate use, by discovering them and working out their structure, the chemists in the lab are adding to the global chemistry community's collective knowledge.  Other chemists in other parts of the world can make use of that knowledge as they undertake their own projects.

If you follow this blog you will hopefully get to learn a bit about what chemists do.  If you take Year 13 Chemistry, my project is going to involve quite a bit of spectroscopy so will help you to gain an understanding of the spectroscopic techniques that you need to be familiar with for Achievement Standard 3.2.  I will also, from time to time, be talking about other things I am getting to do as part of my fellowship.

You are welcome to ask questions about what I am doing, or about what I have covered in a post, by submitting a comment.