Day three consisted of analysing the data to discover whether there were any lipids hiding inside the matrix of the pot and subsequently quantify these. This was done using Gas Chromatography, utilising a high-tech piece of equipment which takes a minute amount of the samples, heats them in a very thin metal tube, and then separates the molecules based on boiling point. This process takes 18 minutes, with the hexane being the first thing to burn off, leaving just the lipids, which are grouped by carbon chain length. These carbon chains ranged from C14 to C22, with some larger molecules such as glycerols and triglycerols being identified as well. These results signify that the pottery found on the site was being used for storing animal proteins (this could be meats or dairy products), as well as indicating the presence of fatty acids. More analysis of this initial data is needed to find out more about the specifics of this data, for example to discover whether the animal products being stored were meat or dairy, and in the case of meat, finding out what animal group was being consumed. Hopefully this further analysis will be complete soon – stay tuned for updates!
Lab Week!
From Monday 3rd June to Wednesday 6th June, five second year students had the pleasure of working in the departments archaeological chemistry labs doing total lipid extraction with PHD researcher Elena, on pottery sherds found on site at Lower Hazel. This process utilized acidified methanol to extract and isolate the lipids, facilitating analysis. The students began by selecting their pottery sherds and preparing them for analysis by chipping off a small section and crushing it up with a pestle and mortar. For this method of pottery analysis, only 1-2g of sample was required, meaning that we could still retain the majority of the pottery sherds for potential further analysis in the future.
Once the pottery had been crushed to a fine powder and decanted into a culture tube, the chemical process could begin. The first extraction used acidified methanol which was added to our pottery sherd sample, before being heated for one hour at 70 degrees Celsius. They then used hexane to extract the lipids from this solution. This groundbreaking protocol was in fact developed here at Bristol University, which remains one of the leading research facilities for this strand of pottery analysis!
This opportunity for lab work hasn’t been available before, and so our second years were the first the trial it. All of the students universally agreed that this experience was a really enjoyable and valuable, with Nicholas describing it as ‘bloody good’! Working in the lab was a fantastic opportunity to get away from the dig site to explore the different aspects of archaeology that happen behind the scenes, giving a completely different perspective on the Lower Hazel site. Hopefully it will be available for students next year!
Special thanks to Elena and Helen for making this experience possible and sharing your knowledge and expertise. In the words of Nicholas, you both ‘went beyond your remit and it’s greatly appreciated!’
Brilliant work and how exciting. I was an archaeology/geology student at Bristol from 1984-7.