After two weeks of working with the Ion Chromatograph (IC), Audrey and I are finally finished running all of our water samples! The Ion Chromatograph analyzes the negatively charged ions in our samples. The main anions we are looking at include Fluoride, Chloride, and Sulphate. In order to operate the IC, Audrey and I worked in tandem. I filled all the 5mL vials with samples, standards or blanks, lidded them and placed them into loading trays. Audrey recorded the sequence order and operated the computer system called Chromeleon. These samples were then loaded into the autosampler. Our jobs are straightforward and relatively short in comparison to working with the mass spec. We are not required to babysit the machine because it is generally reliable. For this we are quite thankful! The process is quite time consuming, however, due to the fact that each vial undergoes three separate injections lasting a total of 66 minutes. Since around 700 injections were done for the entire process, this means that our samples were running constantly for a total of 15,620 minutes or 260 hours or 10.8 days! And these crazy numbers exclude the three days where the machine was not running optimally, so our samples that were run on these days needed to be redone.
The processing of these samples involves several steps. First the autosampler vials are filled and lidded. They are loaded into the autosampler. The water sample is taken up and travels through tubing into an oven with a column that separates the ions by charge. Molecules that have weak ionic interactions leave the column first while ones with stronger ionic interactions leave later. This means that during the 22 minutes it takes to analyze each sample, the different anions leave the column at different times. Fluoride leaves the column first, followed by chloride and then sulphate. After going through a suppressor, the detector reads the current and the data is output to the computer. The data is output in the form of graphs with multiple peaks. Each peak represents a different anion and so we can identify the amount of each anion based on the size of the peaks.
Once we have the data output in the computer, the peaks need to be “massaged”. It is as if the data is going to the spa for a deep tissue massage where it gets an adjustment and everything is put into the correct position. In this case we are adjusting the baselines of the peaks. Once we adjust the data we export it and manipulate it in excel in order to reach the final output. It sounds rather cryptic, but let me assure you that a full explanation would be just as ambiguous!