BATS technician Cathy Rathbun using the High Performance Liquid Chromatography (HPLC) machine

Nutrient analyzer

Nutrients are measured by collecting water at different depths in bottles on the CTD. They are then analyzed in the onshore laboratory with a nutrient analyzer. This machine adds chemicals that turn the water blue when they bind to nutrients. The darker the blue, the more nutrients in the water. The machine measures the intensity of the color and compares it to a standard curve to determine the amount of nutrient in the sample.

High Performance Liquid Chromatography (HPLC) machine

Phytoplankton are the primary producers in the sea and form the base of the marine food chain. All phytoplankton have the pigment Chlorophyll a, just as land plants do.  But phytoplankton also have "accessory" pigments which gives them slightly different coloration. These accessory pigments  can be measured using a High Performance Liquid Chromatography (HPLC) machine. This machine separates the pigments from a water sample and gives a relative measure of the groups of plants that are present in the water.  This is much easier than counting each individual phytoplankton cell!