Sorry for the long interlude between posts. Although we have been pretty busy since our arrival back at station, I need to get some thoughts out more frequently than I have been.

We have started running our pigment samples on the High Performance Liquid Chromatography (HPLC) machine. The software used to run the HPLC is a beast – poorly written and difficult to work with. These are samples that we have been collecting since we arrived at Palmer in October and the samples we collected while we were on the cruise. The samples are pigments that have been trapped on a filter. After Elizabeth removes the pigments from the filter using both organic solvents and some physical mashing of the filters, the isolated pigments are run through the HPLC. By “run” I mean that the pigments are injected into a thin tube and separated out over time. Different pigments pass out from the tube and different times. We can identify the pigments by shinning light on them as they exit the tube. The combination of how long it took for the pigment to flow out of the tube, plus how much light it absorbs helps to identify the pigments. The HPLC results are then analyzed to estimate how much of each type of pigment was present on the filter. And, since we know how much water we filtered, we can then calculate how much mass of each pigment was present in the volume of water we sampled.

At the end of the day, pigments are used to identify the phytoplankton composition of the water. Phytoplankton contain certain pigments in pretty specific ratios. So, by analyzing how much of each pigment is found in our sample, we can begin playing games with estimating what type of phytoplankton and their percent of the total phytoplankton population.

Less intense stuff for the next post…